* [PATCH v9 00/14] migration: Postcopy Preemption
@ 2022-07-07 18:53 Peter Xu
2022-07-07 18:53 ` [PATCH v9 01/14] migration: Add postcopy-preempt capability Peter Xu
` (14 more replies)
0 siblings, 15 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:53 UTC (permalink / raw)
To: qemu-devel
Cc: Dr . David Alan Gilbert, Leonardo Bras Soares Passos,
Manish Mishra, peterx, Juan Quintela, Daniel P . Berrange
Based on:
[PATCH] tests: migration-test: Allow test to run without uffd
https://lore.kernel.org/qemu-devel/20220707184600.24164-1-peterx@redhat.com/
This is v8 of postcopy preempt series. It can also be found here:
https://github.com/xzpeter/qemu/tree/postcopy-preempt
RFC: https://lore.kernel.org/qemu-devel/20220119080929.39485-1-peterx@redhat.com
V1: https://lore.kernel.org/qemu-devel/20220216062809.57179-1-peterx@redhat.com
V2: https://lore.kernel.org/qemu-devel/20220301083925.33483-1-peterx@redhat.com
V3: https://lore.kernel.org/qemu-devel/20220330213908.26608-1-peterx@redhat.com
V4: https://lore.kernel.org/qemu-devel/20220331150857.74406-1-peterx@redhat.com
V5: https://lore.kernel.org/qemu-devel/20220425233847.10393-1-peterx@redhat.com
V6: https://lore.kernel.org/qemu-devel/20220517195730.32312-1-peterx@redhat.com
V7: https://lore.kernel.org/qemu-devel/20220524221151.18225-1-peterx@redhat.com
V8: https://lore.kernel.org/qemu-devel/20220622204920.79061-1-peterx@redhat.com
v9:
- Rebase upon latest master (plus the test fix above on "tests:
migration-test: Allow test to run without uffd")
- Added missing R-bs in v7
Abstract
========
This series added a new migration capability called "postcopy-preempt". It can
be enabled when postcopy is enabled, and it'll simply (but greatly) speed up
postcopy page requests handling process.
Below are some initial postcopy page request latency measurements after the
new series applied.
For each page size, I measured page request latency for three cases:
(a) Vanilla: the old postcopy
(b) Preempt no-break-huge: preempt enabled, x-postcopy-preempt-break-huge=off
(c) Preempt full: preempt enabled, x-postcopy-preempt-break-huge=on
(this is the default option when preempt enabled)
Here x-postcopy-preempt-break-huge parameter is just added in v2 so as to
conditionally disable the behavior to break sending a precopy huge page for
debugging purpose. So when it's off, postcopy will not preempt precopy
sending a huge page, but still postcopy will use its own channel.
I tested it separately to give a rough idea on which part of the change
helped how much of it. The overall benefit should be the comparison
between case (a) and (c).
|-----------+---------+-----------------------+--------------|
| Page size | Vanilla | Preempt no-break-huge | Preempt full |
|-----------+---------+-----------------------+--------------|
| 4K | 10.68 | N/A [*] | 0.57 |
| 2M | 10.58 | 5.49 | 5.02 |
| 1G | 2046.65 | 933.185 | 649.445 |
|-----------+---------+-----------------------+--------------|
[*]: This case is N/A because 4K page does not contain huge page at all
[1] https://github.com/xzpeter/small-stuffs/blob/master/tools/huge_vm/uffd-latency.bpf
TODO List
=========
Avoid precopy write() blocks postcopy
-------------------------------------
I didn't prove this, but I always think the write() syscalls being blocked
for precopy pages can affect postcopy services. If we can solve this
problem then my wild guess is we can further reduce the average page
latency.
Two solutions at least in mind: (1) we could have made the write side of
the migration channel NON_BLOCK too, or (2) multi-threads on send side,
just like multifd, but we may use lock to protect which page to send too
(e.g., the core idea is we should _never_ rely anything on the main thread,
multifd has that dependency on queuing pages only on main thread).
That can definitely be done and thought about later.
Multi-channel for preemption threads
------------------------------------
Currently the postcopy preempt feature use only one extra channel and one
extra thread on dest (no new thread on src QEMU). It should be mostly good
enough for major use cases, but when the postcopy queue is long enough
(e.g. hundreds of vCPUs faulted on different pages) logically we could
still observe more delays in average. Whether growing threads/channels can
solve it is debatable, but sounds worthwhile a try. That's yet another
thing we can think about after this patchset lands.
Logically the design provides space for that - the receiving postcopy
preempt thread can understand all ram-layer migration protocol, and for
multi channel and multi threads we could simply grow that into multile
threads handling the same protocol (with multiple PostcopyTmpPage). The
source needs more thoughts on synchronizations, though, but it shouldn't
affect the whole protocol layer, so should be easy to keep compatible.
Please review, thanks.
Peter Xu (14):
migration: Add postcopy-preempt capability
migration: Postcopy preemption preparation on channel creation
migration: Postcopy preemption enablement
migration: Postcopy recover with preempt enabled
migration: Create the postcopy preempt channel asynchronously
migration: Add property x-postcopy-preempt-break-huge
migration: Add helpers to detect TLS capability
migration: Export tls-[creds|hostname|authz] params to cmdline too
migration: Enable TLS for preempt channel
migration: Respect postcopy request order in preemption mode
tests: Move MigrateCommon upper
tests: Add postcopy tls migration test
tests: Add postcopy tls recovery migration test
tests: Add postcopy preempt tests
migration/channel.c | 9 +-
migration/migration.c | 134 ++++++++++++--
migration/migration.h | 44 ++++-
migration/multifd.c | 4 +-
migration/postcopy-ram.c | 186 +++++++++++++++++++-
migration/postcopy-ram.h | 11 ++
migration/qemu-file.c | 27 +++
migration/qemu-file.h | 1 +
migration/ram.c | 326 +++++++++++++++++++++++++++++++++--
migration/ram.h | 4 +-
migration/savevm.c | 46 +++--
migration/socket.c | 22 ++-
migration/socket.h | 1 +
migration/tls.c | 9 +
migration/tls.h | 4 +
migration/trace-events | 15 +-
qapi/migration.json | 7 +-
tests/qtest/migration-test.c | 286 +++++++++++++++++++++---------
18 files changed, 990 insertions(+), 146 deletions(-)
--
2.32.0
^ permalink raw reply [flat|nested] 22+ messages in thread
* [PATCH v9 01/14] migration: Add postcopy-preempt capability
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
@ 2022-07-07 18:53 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation Peter Xu
` (13 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:53 UTC (permalink / raw)
To: qemu-devel
Cc: Dr . David Alan Gilbert, Leonardo Bras Soares Passos,
Manish Mishra, peterx, Juan Quintela, Daniel P . Berrange
Firstly, postcopy already preempts precopy due to the fact that we do
unqueue_page() first before looking into dirty bits.
However that's not enough, e.g., when there're host huge page enabled, when
sending a precopy huge page, a postcopy request needs to wait until the whole
huge page that is sending to finish. That could introduce quite some delay,
the bigger the huge page is the larger delay it'll bring.
This patch adds a new capability to allow postcopy requests to preempt existing
precopy page during sending a huge page, so that postcopy requests can be
serviced even faster.
Meanwhile to send it even faster, bypass the precopy stream by providing a
standalone postcopy socket for sending requested pages.
Since the new behavior will not be compatible with the old behavior, this will
not be the default, it's enabled only when the new capability is set on both
src/dst QEMUs.
This patch only adds the capability itself, the logic will be added in follow
up patches.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 18 ++++++++++++++++++
migration/migration.h | 1 +
qapi/migration.json | 7 ++++++-
3 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/migration/migration.c b/migration/migration.c
index 78f5057373..ce7bb68cdc 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1297,6 +1297,13 @@ static bool migrate_caps_check(bool *cap_list,
return false;
}
+ if (cap_list[MIGRATION_CAPABILITY_POSTCOPY_PREEMPT]) {
+ if (!cap_list[MIGRATION_CAPABILITY_POSTCOPY_RAM]) {
+ error_setg(errp, "Postcopy preempt requires postcopy-ram");
+ return false;
+ }
+ }
+
return true;
}
@@ -2663,6 +2670,15 @@ bool migrate_background_snapshot(void)
return s->enabled_capabilities[MIGRATION_CAPABILITY_BACKGROUND_SNAPSHOT];
}
+bool migrate_postcopy_preempt(void)
+{
+ MigrationState *s;
+
+ s = migrate_get_current();
+
+ return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_PREEMPT];
+}
+
/* migration thread support */
/*
* Something bad happened to the RP stream, mark an error
@@ -4274,6 +4290,8 @@ static Property migration_properties[] = {
DEFINE_PROP_MIG_CAP("x-compress", MIGRATION_CAPABILITY_COMPRESS),
DEFINE_PROP_MIG_CAP("x-events", MIGRATION_CAPABILITY_EVENTS),
DEFINE_PROP_MIG_CAP("x-postcopy-ram", MIGRATION_CAPABILITY_POSTCOPY_RAM),
+ DEFINE_PROP_MIG_CAP("x-postcopy-preempt",
+ MIGRATION_CAPABILITY_POSTCOPY_PREEMPT),
DEFINE_PROP_MIG_CAP("x-colo", MIGRATION_CAPABILITY_X_COLO),
DEFINE_PROP_MIG_CAP("x-release-ram", MIGRATION_CAPABILITY_RELEASE_RAM),
DEFINE_PROP_MIG_CAP("x-block", MIGRATION_CAPABILITY_BLOCK),
diff --git a/migration/migration.h b/migration/migration.h
index 485d58b95f..d2269c826c 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -400,6 +400,7 @@ int migrate_decompress_threads(void);
bool migrate_use_events(void);
bool migrate_postcopy_blocktime(void);
bool migrate_background_snapshot(void);
+bool migrate_postcopy_preempt(void);
/* Sending on the return path - generic and then for each message type */
void migrate_send_rp_shut(MigrationIncomingState *mis,
diff --git a/qapi/migration.json b/qapi/migration.json
index 7102e474a6..7c60917675 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -467,6 +467,11 @@
# Requires that QEMU be permitted to use locked memory
# for guest RAM pages.
# (since 7.1)
+# @postcopy-preempt: If enabled, the migration process will allow postcopy
+# requests to preempt precopy stream, so postcopy requests
+# will be handled faster. This is a performance feature and
+# should not affect the correctness of postcopy migration.
+# (since 7.1)
#
# Features:
# @unstable: Members @x-colo and @x-ignore-shared are experimental.
@@ -482,7 +487,7 @@
'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
{ 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },
'validate-uuid', 'background-snapshot',
- 'zero-copy-send'] }
+ 'zero-copy-send', 'postcopy-preempt'] }
##
# @MigrationCapabilityStatus:
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
2022-07-07 18:53 ` [PATCH v9 01/14] migration: Add postcopy-preempt capability Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-19 15:15 ` Dr. David Alan Gilbert
2022-07-07 18:55 ` [PATCH v9 03/14] migration: Postcopy preemption enablement Peter Xu
` (12 subsequent siblings)
14 siblings, 1 reply; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
Create a new socket for postcopy to be prepared to send postcopy requested
pages via this specific channel, so as to not get blocked by precopy pages.
A new thread is also created on dest qemu to receive data from this new channel
based on the ram_load_postcopy() routine.
The ram_load_postcopy(POSTCOPY) branch and the thread has not started to
function, and that'll be done in follow up patches.
Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new
thread too to make sure it'll be recycled properly.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 62 +++++++++++++++++++++++----
migration/migration.h | 8 ++++
migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++--
migration/postcopy-ram.h | 10 +++++
migration/ram.c | 25 ++++++++---
migration/ram.h | 4 +-
migration/savevm.c | 20 ++++-----
migration/socket.c | 22 +++++++++-
migration/socket.h | 1 +
migration/trace-events | 5 ++-
10 files changed, 218 insertions(+), 31 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index ce7bb68cdc..9484fec0b2 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void)
mis->page_requested = NULL;
}
+ if (mis->postcopy_qemufile_dst) {
+ migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
+ qemu_fclose(mis->postcopy_qemufile_dst);
+ mis->postcopy_qemufile_dst = NULL;
+ }
+
yank_unregister_instance(MIGRATION_YANK_INSTANCE);
}
@@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error **errp)
migration_incoming_process();
}
+static bool migration_needs_multiple_sockets(void)
+{
+ return migrate_use_multifd() || migrate_postcopy_preempt();
+}
+
void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
{
MigrationIncomingState *mis = migration_incoming_get_current();
Error *local_err = NULL;
bool start_migration;
+ QEMUFile *f;
if (!mis->from_src_file) {
/* The first connection (multifd may have multiple) */
- QEMUFile *f = qemu_file_new_input(ioc);
+ f = qemu_file_new_input(ioc);
if (!migration_incoming_setup(f, errp)) {
return;
@@ -730,13 +742,18 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
/*
* Common migration only needs one channel, so we can start
- * right now. Multifd needs more than one channel, we wait.
+ * right now. Some features need more than one channel, we wait.
*/
- start_migration = !migrate_use_multifd();
+ start_migration = !migration_needs_multiple_sockets();
} else {
/* Multiple connections */
- assert(migrate_use_multifd());
- start_migration = multifd_recv_new_channel(ioc, &local_err);
+ assert(migration_needs_multiple_sockets());
+ if (migrate_use_multifd()) {
+ start_migration = multifd_recv_new_channel(ioc, &local_err);
+ } else if (migrate_postcopy_preempt()) {
+ f = qemu_file_new_input(ioc);
+ start_migration = postcopy_preempt_new_channel(mis, f);
+ }
if (local_err) {
error_propagate(errp, local_err);
return;
@@ -761,11 +778,20 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
bool migration_has_all_channels(void)
{
MigrationIncomingState *mis = migration_incoming_get_current();
- bool all_channels;
- all_channels = multifd_recv_all_channels_created();
+ if (!mis->from_src_file) {
+ return false;
+ }
+
+ if (migrate_use_multifd()) {
+ return multifd_recv_all_channels_created();
+ }
+
+ if (migrate_postcopy_preempt()) {
+ return mis->postcopy_qemufile_dst != NULL;
+ }
- return all_channels && mis->from_src_file != NULL;
+ return true;
}
/*
@@ -1874,6 +1900,12 @@ static void migrate_fd_cleanup(MigrationState *s)
qemu_fclose(tmp);
}
+ if (s->postcopy_qemufile_src) {
+ migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src);
+ qemu_fclose(s->postcopy_qemufile_src);
+ s->postcopy_qemufile_src = NULL;
+ }
+
assert(!migration_is_active(s));
if (s->state == MIGRATION_STATUS_CANCELLING) {
@@ -3269,6 +3301,11 @@ static void migration_completion(MigrationState *s)
qemu_savevm_state_complete_postcopy(s->to_dst_file);
qemu_mutex_unlock_iothread();
+ /* Shutdown the postcopy fast path thread */
+ if (migrate_postcopy_preempt()) {
+ postcopy_preempt_shutdown_file(s);
+ }
+
trace_migration_completion_postcopy_end_after_complete();
} else {
goto fail;
@@ -4157,6 +4194,15 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
}
}
+ /* This needs to be done before resuming a postcopy */
+ if (postcopy_preempt_setup(s, &local_err)) {
+ error_report_err(local_err);
+ migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
+ MIGRATION_STATUS_FAILED);
+ migrate_fd_cleanup(s);
+ return;
+ }
+
if (resume) {
/* Wakeup the main migration thread to do the recovery */
migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
diff --git a/migration/migration.h b/migration/migration.h
index d2269c826c..941c61e543 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -23,6 +23,7 @@
#include "io/channel-buffer.h"
#include "net/announce.h"
#include "qom/object.h"
+#include "postcopy-ram.h"
struct PostcopyBlocktimeContext;
@@ -112,6 +113,11 @@ struct MigrationIncomingState {
* enabled.
*/
unsigned int postcopy_channels;
+ /* QEMUFile for postcopy only; it'll be handled by a separate thread */
+ QEMUFile *postcopy_qemufile_dst;
+ /* Postcopy priority thread is used to receive postcopy requested pages */
+ QemuThread postcopy_prio_thread;
+ bool postcopy_prio_thread_created;
/*
* An array of temp host huge pages to be used, one for each postcopy
* channel.
@@ -192,6 +198,8 @@ struct MigrationState {
QEMUBH *cleanup_bh;
/* Protected by qemu_file_lock */
QEMUFile *to_dst_file;
+ /* Postcopy specific transfer channel */
+ QEMUFile *postcopy_qemufile_src;
QIOChannelBuffer *bioc;
/*
* Protects to_dst_file/from_dst_file pointers. We need to make sure we
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index a66dd536d9..a3561410fe 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -33,6 +33,9 @@
#include "trace.h"
#include "hw/boards.h"
#include "exec/ramblock.h"
+#include "socket.h"
+#include "qemu-file.h"
+#include "yank_functions.h"
/* Arbitrary limit on size of each discard command,
* keeps them around ~200 bytes
@@ -567,6 +570,11 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
{
trace_postcopy_ram_incoming_cleanup_entry();
+ if (mis->postcopy_prio_thread_created) {
+ qemu_thread_join(&mis->postcopy_prio_thread);
+ mis->postcopy_prio_thread_created = false;
+ }
+
if (mis->have_fault_thread) {
Error *local_err = NULL;
@@ -1102,8 +1110,13 @@ static int postcopy_temp_pages_setup(MigrationIncomingState *mis)
int err, i, channels;
void *temp_page;
- /* TODO: will be boosted when enable postcopy preemption */
- mis->postcopy_channels = 1;
+ if (migrate_postcopy_preempt()) {
+ /* If preemption enabled, need extra channel for urgent requests */
+ mis->postcopy_channels = RAM_CHANNEL_MAX;
+ } else {
+ /* Both precopy/postcopy on the same channel */
+ mis->postcopy_channels = 1;
+ }
channels = mis->postcopy_channels;
mis->postcopy_tmp_pages = g_malloc0_n(sizeof(PostcopyTmpPage), channels);
@@ -1170,7 +1183,7 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
return -1;
}
- postcopy_thread_create(mis, &mis->fault_thread, "postcopy/fault",
+ postcopy_thread_create(mis, &mis->fault_thread, "fault-default",
postcopy_ram_fault_thread, QEMU_THREAD_JOINABLE);
mis->have_fault_thread = true;
@@ -1185,6 +1198,16 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
return -1;
}
+ if (migrate_postcopy_preempt()) {
+ /*
+ * This thread needs to be created after the temp pages because
+ * it'll fetch RAM_CHANNEL_POSTCOPY PostcopyTmpPage immediately.
+ */
+ postcopy_thread_create(mis, &mis->postcopy_prio_thread, "fault-fast",
+ postcopy_preempt_thread, QEMU_THREAD_JOINABLE);
+ mis->postcopy_prio_thread_created = true;
+ }
+
trace_postcopy_ram_enable_notify();
return 0;
@@ -1514,3 +1537,66 @@ void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd)
}
}
}
+
+bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
+{
+ /*
+ * The new loading channel has its own threads, so it needs to be
+ * blocked too. It's by default true, just be explicit.
+ */
+ qemu_file_set_blocking(file, true);
+ mis->postcopy_qemufile_dst = file;
+ trace_postcopy_preempt_new_channel();
+
+ /* Start the migration immediately */
+ return true;
+}
+
+int postcopy_preempt_setup(MigrationState *s, Error **errp)
+{
+ QIOChannel *ioc;
+
+ if (!migrate_postcopy_preempt()) {
+ return 0;
+ }
+
+ if (!migrate_multi_channels_is_allowed()) {
+ error_setg(errp, "Postcopy preempt is not supported as current "
+ "migration stream does not support multi-channels.");
+ return -1;
+ }
+
+ ioc = socket_send_channel_create_sync(errp);
+
+ if (ioc == NULL) {
+ return -1;
+ }
+
+ migration_ioc_register_yank(ioc);
+ s->postcopy_qemufile_src = qemu_file_new_output(ioc);
+
+ trace_postcopy_preempt_new_channel();
+
+ return 0;
+}
+
+void *postcopy_preempt_thread(void *opaque)
+{
+ MigrationIncomingState *mis = opaque;
+ int ret;
+
+ trace_postcopy_preempt_thread_entry();
+
+ rcu_register_thread();
+
+ qemu_sem_post(&mis->thread_sync_sem);
+
+ /* Sending RAM_SAVE_FLAG_EOS to terminate this thread */
+ ret = ram_load_postcopy(mis->postcopy_qemufile_dst, RAM_CHANNEL_POSTCOPY);
+
+ rcu_unregister_thread();
+
+ trace_postcopy_preempt_thread_exit();
+
+ return ret == 0 ? NULL : (void *)-1;
+}
diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index 07684c0e1d..34b1080cde 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -183,4 +183,14 @@ int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
uint64_t client_addr, uint64_t offset);
+/* Hard-code channels for now for postcopy preemption */
+enum PostcopyChannels {
+ RAM_CHANNEL_PRECOPY = 0,
+ RAM_CHANNEL_POSTCOPY = 1,
+ RAM_CHANNEL_MAX,
+};
+
+bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
+int postcopy_preempt_setup(MigrationState *s, Error **errp);
+
#endif
diff --git a/migration/ram.c b/migration/ram.c
index 01f9cc1d72..e4364c0bff 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3659,15 +3659,15 @@ int ram_postcopy_incoming_init(MigrationIncomingState *mis)
* rcu_read_lock is taken prior to this being called.
*
* @f: QEMUFile where to send the data
+ * @channel: the channel to use for loading
*/
-int ram_load_postcopy(QEMUFile *f)
+int ram_load_postcopy(QEMUFile *f, int channel)
{
int flags = 0, ret = 0;
bool place_needed = false;
bool matches_target_page_size = false;
MigrationIncomingState *mis = migration_incoming_get_current();
- /* Currently we only use channel 0. TODO: use all the channels */
- PostcopyTmpPage *tmp_page = &mis->postcopy_tmp_pages[0];
+ PostcopyTmpPage *tmp_page = &mis->postcopy_tmp_pages[channel];
while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) {
ram_addr_t addr;
@@ -3691,7 +3691,7 @@ int ram_load_postcopy(QEMUFile *f)
flags = addr & ~TARGET_PAGE_MASK;
addr &= TARGET_PAGE_MASK;
- trace_ram_load_postcopy_loop((uint64_t)addr, flags);
+ trace_ram_load_postcopy_loop(channel, (uint64_t)addr, flags);
if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
RAM_SAVE_FLAG_COMPRESS_PAGE)) {
block = ram_block_from_stream(mis, f, flags);
@@ -3732,10 +3732,10 @@ int ram_load_postcopy(QEMUFile *f)
} else if (tmp_page->host_addr !=
host_page_from_ram_block_offset(block, addr)) {
/* not the 1st TP within the HP */
- error_report("Non-same host page detected. "
+ error_report("Non-same host page detected on channel %d: "
"Target host page %p, received host page %p "
"(rb %s offset 0x"RAM_ADDR_FMT" target_pages %d)",
- tmp_page->host_addr,
+ channel, tmp_page->host_addr,
host_page_from_ram_block_offset(block, addr),
block->idstr, addr, tmp_page->target_pages);
ret = -EINVAL;
@@ -4122,7 +4122,12 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
*/
WITH_RCU_READ_LOCK_GUARD() {
if (postcopy_running) {
- ret = ram_load_postcopy(f);
+ /*
+ * Note! Here RAM_CHANNEL_PRECOPY is the precopy channel of
+ * postcopy migration, we have another RAM_CHANNEL_POSTCOPY to
+ * service fast page faults.
+ */
+ ret = ram_load_postcopy(f, RAM_CHANNEL_PRECOPY);
} else {
ret = ram_load_precopy(f);
}
@@ -4284,6 +4289,12 @@ static int ram_resume_prepare(MigrationState *s, void *opaque)
return 0;
}
+void postcopy_preempt_shutdown_file(MigrationState *s)
+{
+ qemu_put_be64(s->postcopy_qemufile_src, RAM_SAVE_FLAG_EOS);
+ qemu_fflush(s->postcopy_qemufile_src);
+}
+
static SaveVMHandlers savevm_ram_handlers = {
.save_setup = ram_save_setup,
.save_live_iterate = ram_save_iterate,
diff --git a/migration/ram.h b/migration/ram.h
index ded0a3a086..5d90945a6e 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -61,7 +61,7 @@ void ram_postcopy_send_discard_bitmap(MigrationState *ms);
/* For incoming postcopy discard */
int ram_discard_range(const char *block_name, uint64_t start, size_t length);
int ram_postcopy_incoming_init(MigrationIncomingState *mis);
-int ram_load_postcopy(QEMUFile *f);
+int ram_load_postcopy(QEMUFile *f, int channel);
void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
@@ -73,6 +73,8 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file,
const char *block_name);
int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb);
bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t start);
+void postcopy_preempt_shutdown_file(MigrationState *s);
+void *postcopy_preempt_thread(void *opaque);
/* ram cache */
int colo_init_ram_cache(void);
diff --git a/migration/savevm.c b/migration/savevm.c
index e8a1b96fcd..e3af03cb9b 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2540,16 +2540,6 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
{
int i;
- /*
- * If network is interrupted, any temp page we received will be useless
- * because we didn't mark them as "received" in receivedmap. After a
- * proper recovery later (which will sync src dirty bitmap with receivedmap
- * on dest) these cached small pages will be resent again.
- */
- for (i = 0; i < mis->postcopy_channels; i++) {
- postcopy_temp_page_reset(&mis->postcopy_tmp_pages[i]);
- }
-
trace_postcopy_pause_incoming();
assert(migrate_postcopy_ram());
@@ -2578,6 +2568,16 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
/* Notify the fault thread for the invalidated file handle */
postcopy_fault_thread_notify(mis);
+ /*
+ * If network is interrupted, any temp page we received will be useless
+ * because we didn't mark them as "received" in receivedmap. After a
+ * proper recovery later (which will sync src dirty bitmap with receivedmap
+ * on dest) these cached small pages will be resent again.
+ */
+ for (i = 0; i < mis->postcopy_channels; i++) {
+ postcopy_temp_page_reset(&mis->postcopy_tmp_pages[i]);
+ }
+
error_report("Detected IO failure for postcopy. "
"Migration paused.");
diff --git a/migration/socket.c b/migration/socket.c
index 4fd5e85f50..e6fdf3c5e1 100644
--- a/migration/socket.c
+++ b/migration/socket.c
@@ -26,7 +26,7 @@
#include "io/channel-socket.h"
#include "io/net-listener.h"
#include "trace.h"
-
+#include "postcopy-ram.h"
struct SocketOutgoingArgs {
SocketAddress *saddr;
@@ -39,6 +39,24 @@ void socket_send_channel_create(QIOTaskFunc f, void *data)
f, data, NULL, NULL);
}
+QIOChannel *socket_send_channel_create_sync(Error **errp)
+{
+ QIOChannelSocket *sioc = qio_channel_socket_new();
+
+ if (!outgoing_args.saddr) {
+ object_unref(OBJECT(sioc));
+ error_setg(errp, "Initial sock address not set!");
+ return NULL;
+ }
+
+ if (qio_channel_socket_connect_sync(sioc, outgoing_args.saddr, errp) < 0) {
+ object_unref(OBJECT(sioc));
+ return NULL;
+ }
+
+ return QIO_CHANNEL(sioc);
+}
+
int socket_send_channel_destroy(QIOChannel *send)
{
/* Remove channel */
@@ -166,6 +184,8 @@ socket_start_incoming_migration_internal(SocketAddress *saddr,
if (migrate_use_multifd()) {
num = migrate_multifd_channels();
+ } else if (migrate_postcopy_preempt()) {
+ num = RAM_CHANNEL_MAX;
}
if (qio_net_listener_open_sync(listener, saddr, num, errp) < 0) {
diff --git a/migration/socket.h b/migration/socket.h
index 891dbccceb..dc54df4e6c 100644
--- a/migration/socket.h
+++ b/migration/socket.h
@@ -21,6 +21,7 @@
#include "io/task.h"
void socket_send_channel_create(QIOTaskFunc f, void *data);
+QIOChannel *socket_send_channel_create_sync(Error **errp);
int socket_send_channel_destroy(QIOChannel *send);
void socket_start_incoming_migration(const char *str, Error **errp);
diff --git a/migration/trace-events b/migration/trace-events
index 1aec580e92..4bc787cf0c 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -91,7 +91,7 @@ migration_bitmap_clear_dirty(char *str, uint64_t start, uint64_t size, unsigned
migration_throttle(void) ""
ram_discard_range(const char *rbname, uint64_t start, size_t len) "%s: start: %" PRIx64 " %zx"
ram_load_loop(const char *rbname, uint64_t addr, int flags, void *host) "%s: addr: 0x%" PRIx64 " flags: 0x%x host: %p"
-ram_load_postcopy_loop(uint64_t addr, int flags) "@%" PRIx64 " %x"
+ram_load_postcopy_loop(int channel, uint64_t addr, int flags) "chan=%d addr=0x%" PRIx64 " flags=0x%x"
ram_postcopy_send_discard_bitmap(void) ""
ram_save_page(const char *rbname, uint64_t offset, void *host) "%s: offset: 0x%" PRIx64 " host: %p"
ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s: start: 0x%zx len: 0x%zx"
@@ -278,6 +278,9 @@ postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_off
postcopy_request_shared_page_present(const char *sharer, const char *rb, uint64_t rb_offset) "%s already %s offset 0x%"PRIx64
postcopy_wake_shared(uint64_t client_addr, const char *rb) "at 0x%"PRIx64" in %s"
postcopy_page_req_del(void *addr, int count) "resolved page req %p total %d"
+postcopy_preempt_new_channel(void) ""
+postcopy_preempt_thread_entry(void) ""
+postcopy_preempt_thread_exit(void) ""
get_mem_fault_cpu_index(int cpu, uint32_t pid) "cpu: %d, pid: %u"
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 03/14] migration: Postcopy preemption enablement
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
2022-07-07 18:53 ` [PATCH v9 01/14] migration: Add postcopy-preempt capability Peter Xu
2022-07-07 18:55 ` [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 04/14] migration: Postcopy recover with preempt enabled Peter Xu
` (11 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
This patch enables postcopy-preempt feature.
It contains two major changes to the migration logic:
(1) Postcopy requests are now sent via a different socket from precopy
background migration stream, so as to be isolated from very high page
request delays.
(2) For huge page enabled hosts: when there's postcopy requests, they can now
intercept a partial sending of huge host pages on src QEMU.
After this patch, we'll live migrate a VM with two channels for postcopy: (1)
PRECOPY channel, which is the default channel that transfers background pages;
and (2) POSTCOPY channel, which only transfers requested pages.
There's no strict rule of which channel to use, e.g., if a requested page is
already being transferred on precopy channel, then we will keep using the same
precopy channel to transfer the page even if it's explicitly requested. In 99%
of the cases we'll prioritize the channels so we send requested page via the
postcopy channel as long as possible.
On the source QEMU, when we found a postcopy request, we'll interrupt the
PRECOPY channel sending process and quickly switch to the POSTCOPY channel.
After we serviced all the high priority postcopy pages, we'll switch back to
PRECOPY channel so that we'll continue to send the interrupted huge page again.
There's no new thread introduced on src QEMU.
On the destination QEMU, one new thread is introduced to receive page data from
the postcopy specific socket (done in the preparation patch).
This patch has a side effect: after sending postcopy pages, previously we'll
assume the guest will access follow up pages so we'll keep sending from there.
Now it's changed. Instead of going on with a postcopy requested page, we'll go
back and continue sending the precopy huge page (which can be intercepted by a
postcopy request so the huge page can be sent partially before).
Whether that's a problem is debatable, because "assuming the guest will
continue to access the next page" may not really suite when huge pages are
used, especially if the huge page is large (e.g. 1GB pages). So that locality
hint is much meaningless if huge pages are used.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 2 +
migration/migration.h | 2 +-
migration/ram.c | 251 +++++++++++++++++++++++++++++++++++++++--
migration/trace-events | 7 ++
4 files changed, 253 insertions(+), 9 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 9484fec0b2..5e20d1c941 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3189,6 +3189,8 @@ static int postcopy_start(MigrationState *ms)
MIGRATION_STATUS_FAILED);
}
+ trace_postcopy_preempt_enabled(migrate_postcopy_preempt());
+
return ret;
fail_closefb:
diff --git a/migration/migration.h b/migration/migration.h
index 941c61e543..ff714c235f 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -68,7 +68,7 @@ typedef struct {
struct MigrationIncomingState {
QEMUFile *from_src_file;
/* Previously received RAM's RAMBlock pointer */
- RAMBlock *last_recv_block;
+ RAMBlock *last_recv_block[RAM_CHANNEL_MAX];
/* A hook to allow cleanup at the end of incoming migration */
void *transport_data;
void (*transport_cleanup)(void *data);
diff --git a/migration/ram.c b/migration/ram.c
index e4364c0bff..65b08c4edb 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -296,6 +296,20 @@ struct RAMSrcPageRequest {
QSIMPLEQ_ENTRY(RAMSrcPageRequest) next_req;
};
+typedef struct {
+ /*
+ * Cached ramblock/offset values if preempted. They're only meaningful if
+ * preempted==true below.
+ */
+ RAMBlock *ram_block;
+ unsigned long ram_page;
+ /*
+ * Whether a postcopy preemption just happened. Will be reset after
+ * precopy recovered to background migration.
+ */
+ bool preempted;
+} PostcopyPreemptState;
+
/* State of RAM for migration */
struct RAMState {
/* QEMUFile used for this migration */
@@ -350,6 +364,14 @@ struct RAMState {
/* Queue of outstanding page requests from the destination */
QemuMutex src_page_req_mutex;
QSIMPLEQ_HEAD(, RAMSrcPageRequest) src_page_requests;
+
+ /* Postcopy preemption informations */
+ PostcopyPreemptState postcopy_preempt_state;
+ /*
+ * Current channel we're using on src VM. Only valid if postcopy-preempt
+ * is enabled.
+ */
+ unsigned int postcopy_channel;
};
typedef struct RAMState RAMState;
@@ -357,6 +379,11 @@ static RAMState *ram_state;
static NotifierWithReturnList precopy_notifier_list;
+static void postcopy_preempt_reset(RAMState *rs)
+{
+ memset(&rs->postcopy_preempt_state, 0, sizeof(PostcopyPreemptState));
+}
+
/* Whether postcopy has queued requests? */
static bool postcopy_has_request(RAMState *rs)
{
@@ -1947,6 +1974,55 @@ void ram_write_tracking_stop(void)
}
#endif /* defined(__linux__) */
+/*
+ * Check whether two addr/offset of the ramblock falls onto the same host huge
+ * page. Returns true if so, false otherwise.
+ */
+static bool offset_on_same_huge_page(RAMBlock *rb, uint64_t addr1,
+ uint64_t addr2)
+{
+ size_t page_size = qemu_ram_pagesize(rb);
+
+ addr1 = ROUND_DOWN(addr1, page_size);
+ addr2 = ROUND_DOWN(addr2, page_size);
+
+ return addr1 == addr2;
+}
+
+/*
+ * Whether a previous preempted precopy huge page contains current requested
+ * page? Returns true if so, false otherwise.
+ *
+ * This should really happen very rarely, because it means when we were sending
+ * during background migration for postcopy we're sending exactly the page that
+ * some vcpu got faulted on on dest node. When it happens, we probably don't
+ * need to do much but drop the request, because we know right after we restore
+ * the precopy stream it'll be serviced. It'll slightly affect the order of
+ * postcopy requests to be serviced (e.g. it'll be the same as we move current
+ * request to the end of the queue) but it shouldn't be a big deal. The most
+ * imporant thing is we can _never_ try to send a partial-sent huge page on the
+ * POSTCOPY channel again, otherwise that huge page will got "split brain" on
+ * two channels (PRECOPY, POSTCOPY).
+ */
+static bool postcopy_preempted_contains(RAMState *rs, RAMBlock *block,
+ ram_addr_t offset)
+{
+ PostcopyPreemptState *state = &rs->postcopy_preempt_state;
+
+ /* No preemption at all? */
+ if (!state->preempted) {
+ return false;
+ }
+
+ /* Not even the same ramblock? */
+ if (state->ram_block != block) {
+ return false;
+ }
+
+ return offset_on_same_huge_page(block, offset,
+ state->ram_page << TARGET_PAGE_BITS);
+}
+
/**
* get_queued_page: unqueue a page from the postcopy requests
*
@@ -1962,9 +2038,17 @@ static bool get_queued_page(RAMState *rs, PageSearchStatus *pss)
RAMBlock *block;
ram_addr_t offset;
+again:
block = unqueue_page(rs, &offset);
- if (!block) {
+ if (block) {
+ /* See comment above postcopy_preempted_contains() */
+ if (postcopy_preempted_contains(rs, block, offset)) {
+ trace_postcopy_preempt_hit(block->idstr, offset);
+ /* This request is dropped */
+ goto again;
+ }
+ } else {
/*
* Poll write faults too if background snapshot is enabled; that's
* when we have vcpus got blocked by the write protected pages.
@@ -2180,6 +2264,117 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss)
return ram_save_page(rs, pss);
}
+static bool postcopy_needs_preempt(RAMState *rs, PageSearchStatus *pss)
+{
+ /* Not enabled eager preempt? Then never do that. */
+ if (!migrate_postcopy_preempt()) {
+ return false;
+ }
+
+ /* If the ramblock we're sending is a small page? Never bother. */
+ if (qemu_ram_pagesize(pss->block) == TARGET_PAGE_SIZE) {
+ return false;
+ }
+
+ /* Not in postcopy at all? */
+ if (!migration_in_postcopy()) {
+ return false;
+ }
+
+ /*
+ * If we're already handling a postcopy request, don't preempt as this page
+ * has got the same high priority.
+ */
+ if (pss->postcopy_requested) {
+ return false;
+ }
+
+ /* If there's postcopy requests, then check it up! */
+ return postcopy_has_request(rs);
+}
+
+/* Returns true if we preempted precopy, false otherwise */
+static void postcopy_do_preempt(RAMState *rs, PageSearchStatus *pss)
+{
+ PostcopyPreemptState *p_state = &rs->postcopy_preempt_state;
+
+ trace_postcopy_preempt_triggered(pss->block->idstr, pss->page);
+
+ /*
+ * Time to preempt precopy. Cache current PSS into preempt state, so that
+ * after handling the postcopy pages we can recover to it. We need to do
+ * so because the dest VM will have partial of the precopy huge page kept
+ * over in its tmp huge page caches; better move on with it when we can.
+ */
+ p_state->ram_block = pss->block;
+ p_state->ram_page = pss->page;
+ p_state->preempted = true;
+}
+
+/* Whether we're preempted by a postcopy request during sending a huge page */
+static bool postcopy_preempt_triggered(RAMState *rs)
+{
+ return rs->postcopy_preempt_state.preempted;
+}
+
+static void postcopy_preempt_restore(RAMState *rs, PageSearchStatus *pss)
+{
+ PostcopyPreemptState *state = &rs->postcopy_preempt_state;
+
+ assert(state->preempted);
+
+ pss->block = state->ram_block;
+ pss->page = state->ram_page;
+ /* This is not a postcopy request but restoring previous precopy */
+ pss->postcopy_requested = false;
+
+ trace_postcopy_preempt_restored(pss->block->idstr, pss->page);
+
+ /* Reset preempt state, most importantly, set preempted==false */
+ postcopy_preempt_reset(rs);
+}
+
+static void postcopy_preempt_choose_channel(RAMState *rs, PageSearchStatus *pss)
+{
+ MigrationState *s = migrate_get_current();
+ unsigned int channel;
+ QEMUFile *next;
+
+ channel = pss->postcopy_requested ?
+ RAM_CHANNEL_POSTCOPY : RAM_CHANNEL_PRECOPY;
+
+ if (channel != rs->postcopy_channel) {
+ if (channel == RAM_CHANNEL_PRECOPY) {
+ next = s->to_dst_file;
+ } else {
+ next = s->postcopy_qemufile_src;
+ }
+ /* Update and cache the current channel */
+ rs->f = next;
+ rs->postcopy_channel = channel;
+
+ /*
+ * If channel switched, reset last_sent_block since the old sent block
+ * may not be on the same channel.
+ */
+ rs->last_sent_block = NULL;
+
+ trace_postcopy_preempt_switch_channel(channel);
+ }
+
+ trace_postcopy_preempt_send_host_page(pss->block->idstr, pss->page);
+}
+
+/* We need to make sure rs->f always points to the default channel elsewhere */
+static void postcopy_preempt_reset_channel(RAMState *rs)
+{
+ if (migrate_postcopy_preempt() && migration_in_postcopy()) {
+ rs->postcopy_channel = RAM_CHANNEL_PRECOPY;
+ rs->f = migrate_get_current()->to_dst_file;
+ trace_postcopy_preempt_reset_channel();
+ }
+}
+
/**
* ram_save_host_page: save a whole host page
*
@@ -2211,7 +2406,16 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss)
return 0;
}
+ if (migrate_postcopy_preempt() && migration_in_postcopy()) {
+ postcopy_preempt_choose_channel(rs, pss);
+ }
+
do {
+ if (postcopy_needs_preempt(rs, pss)) {
+ postcopy_do_preempt(rs, pss);
+ break;
+ }
+
/* Check the pages is dirty and if it is send it */
if (migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
tmppages = ram_save_target_page(rs, pss);
@@ -2235,6 +2439,19 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss)
/* The offset we leave with is the min boundary of host page and block */
pss->page = MIN(pss->page, hostpage_boundary);
+ /*
+ * When with postcopy preempt mode, flush the data as soon as possible for
+ * postcopy requests, because we've already sent a whole huge page, so the
+ * dst node should already have enough resource to atomically filling in
+ * the current missing page.
+ *
+ * More importantly, when using separate postcopy channel, we must do
+ * explicit flush or it won't flush until the buffer is full.
+ */
+ if (migrate_postcopy_preempt() && pss->postcopy_requested) {
+ qemu_fflush(rs->f);
+ }
+
res = ram_save_release_protection(rs, pss, start_page);
return (res < 0 ? res : pages);
}
@@ -2276,8 +2493,17 @@ static int ram_find_and_save_block(RAMState *rs)
found = get_queued_page(rs, &pss);
if (!found) {
- /* priority queue empty, so just search for something dirty */
- found = find_dirty_block(rs, &pss, &again);
+ /*
+ * Recover previous precopy ramblock/offset if postcopy has
+ * preempted precopy. Otherwise find the next dirty bit.
+ */
+ if (postcopy_preempt_triggered(rs)) {
+ postcopy_preempt_restore(rs, &pss);
+ found = true;
+ } else {
+ /* priority queue empty, so just search for something dirty */
+ found = find_dirty_block(rs, &pss, &again);
+ }
}
if (found) {
@@ -2405,6 +2631,8 @@ static void ram_state_reset(RAMState *rs)
rs->last_page = 0;
rs->last_version = ram_list.version;
rs->xbzrle_enabled = false;
+ postcopy_preempt_reset(rs);
+ rs->postcopy_channel = RAM_CHANNEL_PRECOPY;
}
#define MAX_WAIT 50 /* ms, half buffered_file limit */
@@ -3048,6 +3276,8 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
}
qemu_mutex_unlock(&rs->bitmap_mutex);
+ postcopy_preempt_reset_channel(rs);
+
/*
* Must occur before EOS (or any QEMUFile operation)
* because of RDMA protocol.
@@ -3125,6 +3355,8 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
return ret;
}
+ postcopy_preempt_reset_channel(rs);
+
ret = multifd_send_sync_main(rs->f);
if (ret < 0) {
return ret;
@@ -3209,11 +3441,13 @@ static int load_xbzrle(QEMUFile *f, ram_addr_t addr, void *host)
* @mis: the migration incoming state pointer
* @f: QEMUFile where to read the data from
* @flags: Page flags (mostly to see if it's a continuation of previous block)
+ * @channel: the channel we're using
*/
static inline RAMBlock *ram_block_from_stream(MigrationIncomingState *mis,
- QEMUFile *f, int flags)
+ QEMUFile *f, int flags,
+ int channel)
{
- RAMBlock *block = mis->last_recv_block;
+ RAMBlock *block = mis->last_recv_block[channel];
char id[256];
uint8_t len;
@@ -3240,7 +3474,7 @@ static inline RAMBlock *ram_block_from_stream(MigrationIncomingState *mis,
return NULL;
}
- mis->last_recv_block = block;
+ mis->last_recv_block[channel] = block;
return block;
}
@@ -3694,7 +3928,7 @@ int ram_load_postcopy(QEMUFile *f, int channel)
trace_ram_load_postcopy_loop(channel, (uint64_t)addr, flags);
if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
RAM_SAVE_FLAG_COMPRESS_PAGE)) {
- block = ram_block_from_stream(mis, f, flags);
+ block = ram_block_from_stream(mis, f, flags, channel);
if (!block) {
ret = -EINVAL;
break;
@@ -3945,7 +4179,8 @@ static int ram_load_precopy(QEMUFile *f)
if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
- RAMBlock *block = ram_block_from_stream(mis, f, flags);
+ RAMBlock *block = ram_block_from_stream(mis, f, flags,
+ RAM_CHANNEL_PRECOPY);
host = host_from_ram_block_offset(block, addr);
/*
diff --git a/migration/trace-events b/migration/trace-events
index 4bc787cf0c..69f311169a 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -111,6 +111,12 @@ ram_load_complete(int ret, uint64_t seq_iter) "exit_code %d seq iteration %" PRI
ram_write_tracking_ramblock_start(const char *block_id, size_t page_size, void *addr, size_t length) "%s: page_size: %zu addr: %p length: %zu"
ram_write_tracking_ramblock_stop(const char *block_id, size_t page_size, void *addr, size_t length) "%s: page_size: %zu addr: %p length: %zu"
unqueue_page(char *block, uint64_t offset, bool dirty) "ramblock '%s' offset 0x%"PRIx64" dirty %d"
+postcopy_preempt_triggered(char *str, unsigned long page) "during sending ramblock %s offset 0x%lx"
+postcopy_preempt_restored(char *str, unsigned long page) "ramblock %s offset 0x%lx"
+postcopy_preempt_hit(char *str, uint64_t offset) "ramblock %s offset 0x%"PRIx64
+postcopy_preempt_send_host_page(char *str, uint64_t offset) "ramblock %s offset 0x%"PRIx64
+postcopy_preempt_switch_channel(int channel) "%d"
+postcopy_preempt_reset_channel(void) ""
# multifd.c
multifd_new_send_channel_async(uint8_t id) "channel %u"
@@ -176,6 +182,7 @@ migration_thread_low_pending(uint64_t pending) "%" PRIu64
migrate_transferred(uint64_t tranferred, uint64_t time_spent, uint64_t bandwidth, uint64_t size) "transferred %" PRIu64 " time_spent %" PRIu64 " bandwidth %" PRIu64 " max_size %" PRId64
process_incoming_migration_co_end(int ret, int ps) "ret=%d postcopy-state=%d"
process_incoming_migration_co_postcopy_end_main(void) ""
+postcopy_preempt_enabled(bool value) "%d"
# channel.c
migration_set_incoming_channel(void *ioc, const char *ioctype) "ioc=%p ioctype=%s"
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 04/14] migration: Postcopy recover with preempt enabled
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (2 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 03/14] migration: Postcopy preemption enablement Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 05/14] migration: Create the postcopy preempt channel asynchronously Peter Xu
` (10 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
To allow postcopy recovery, the ram fast load (preempt-only) dest QEMU thread
needs similar handling on fault tolerance. When ram_load_postcopy() fails,
instead of stopping the thread it halts with a semaphore, preparing to be
kicked again when recovery is detected.
A mutex is introduced to make sure there's no concurrent operation upon the
socket. To make it simple, the fast ram load thread will take the mutex during
its whole procedure, and only release it if it's paused. The fast-path socket
will be properly released by the main loading thread safely when there's
network failures during postcopy with that mutex held.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 27 +++++++++++++++++++++++----
migration/migration.h | 19 +++++++++++++++++++
migration/postcopy-ram.c | 25 +++++++++++++++++++++++--
migration/qemu-file.c | 27 +++++++++++++++++++++++++++
migration/qemu-file.h | 1 +
migration/savevm.c | 26 ++++++++++++++++++++++++--
migration/trace-events | 2 ++
7 files changed, 119 insertions(+), 8 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index 5e20d1c941..db82ecbdcd 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -215,9 +215,11 @@ void migration_object_init(void)
current_incoming->postcopy_remote_fds =
g_array_new(FALSE, TRUE, sizeof(struct PostCopyFD));
qemu_mutex_init(¤t_incoming->rp_mutex);
+ qemu_mutex_init(¤t_incoming->postcopy_prio_thread_mutex);
qemu_event_init(¤t_incoming->main_thread_load_event, false);
qemu_sem_init(¤t_incoming->postcopy_pause_sem_dst, 0);
qemu_sem_init(¤t_incoming->postcopy_pause_sem_fault, 0);
+ qemu_sem_init(¤t_incoming->postcopy_pause_sem_fast_load, 0);
qemu_mutex_init(¤t_incoming->page_request_mutex);
current_incoming->page_requested = g_tree_new(page_request_addr_cmp);
@@ -697,9 +699,9 @@ static bool postcopy_try_recover(void)
/*
* Here, we only wake up the main loading thread (while the
- * fault thread will still be waiting), so that we can receive
+ * rest threads will still be waiting), so that we can receive
* commands from source now, and answer it if needed. The
- * fault thread will be woken up afterwards until we are sure
+ * rest threads will be woken up afterwards until we are sure
* that source is ready to reply to page requests.
*/
qemu_sem_post(&mis->postcopy_pause_sem_dst);
@@ -3502,6 +3504,18 @@ static MigThrError postcopy_pause(MigrationState *s)
qemu_file_shutdown(file);
qemu_fclose(file);
+ /*
+ * Do the same to postcopy fast path socket too if there is. No
+ * locking needed because no racer as long as we do this before setting
+ * status to paused.
+ */
+ if (s->postcopy_qemufile_src) {
+ migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src);
+ qemu_file_shutdown(s->postcopy_qemufile_src);
+ qemu_fclose(s->postcopy_qemufile_src);
+ s->postcopy_qemufile_src = NULL;
+ }
+
migrate_set_state(&s->state, s->state,
MIGRATION_STATUS_POSTCOPY_PAUSED);
@@ -3557,8 +3571,13 @@ static MigThrError migration_detect_error(MigrationState *s)
return MIG_THR_ERR_FATAL;
}
- /* Try to detect any file errors */
- ret = qemu_file_get_error_obj(s->to_dst_file, &local_error);
+ /*
+ * Try to detect any file errors. Note that postcopy_qemufile_src will
+ * be NULL when postcopy preempt is not enabled.
+ */
+ ret = qemu_file_get_error_obj_any(s->to_dst_file,
+ s->postcopy_qemufile_src,
+ &local_error);
if (!ret) {
/* Everything is fine */
assert(!local_error);
diff --git a/migration/migration.h b/migration/migration.h
index ff714c235f..9220cec6bd 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -118,6 +118,18 @@ struct MigrationIncomingState {
/* Postcopy priority thread is used to receive postcopy requested pages */
QemuThread postcopy_prio_thread;
bool postcopy_prio_thread_created;
+ /*
+ * Used to sync between the ram load main thread and the fast ram load
+ * thread. It protects postcopy_qemufile_dst, which is the postcopy
+ * fast channel.
+ *
+ * The ram fast load thread will take it mostly for the whole lifecycle
+ * because it needs to continuously read data from the channel, and
+ * it'll only release this mutex if postcopy is interrupted, so that
+ * the ram load main thread will take this mutex over and properly
+ * release the broken channel.
+ */
+ QemuMutex postcopy_prio_thread_mutex;
/*
* An array of temp host huge pages to be used, one for each postcopy
* channel.
@@ -147,6 +159,13 @@ struct MigrationIncomingState {
/* notify PAUSED postcopy incoming migrations to try to continue */
QemuSemaphore postcopy_pause_sem_dst;
QemuSemaphore postcopy_pause_sem_fault;
+ /*
+ * This semaphore is used to allow the ram fast load thread (only when
+ * postcopy preempt is enabled) fall into sleep when there's network
+ * interruption detected. When the recovery is done, the main load
+ * thread will kick the fast ram load thread using this semaphore.
+ */
+ QemuSemaphore postcopy_pause_sem_fast_load;
/* List of listening socket addresses */
SocketAddressList *socket_address_list;
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index a3561410fe..84f7b1526e 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1580,6 +1580,15 @@ int postcopy_preempt_setup(MigrationState *s, Error **errp)
return 0;
}
+static void postcopy_pause_ram_fast_load(MigrationIncomingState *mis)
+{
+ trace_postcopy_pause_fast_load();
+ qemu_mutex_unlock(&mis->postcopy_prio_thread_mutex);
+ qemu_sem_wait(&mis->postcopy_pause_sem_fast_load);
+ qemu_mutex_lock(&mis->postcopy_prio_thread_mutex);
+ trace_postcopy_pause_fast_load_continued();
+}
+
void *postcopy_preempt_thread(void *opaque)
{
MigrationIncomingState *mis = opaque;
@@ -1592,11 +1601,23 @@ void *postcopy_preempt_thread(void *opaque)
qemu_sem_post(&mis->thread_sync_sem);
/* Sending RAM_SAVE_FLAG_EOS to terminate this thread */
- ret = ram_load_postcopy(mis->postcopy_qemufile_dst, RAM_CHANNEL_POSTCOPY);
+ qemu_mutex_lock(&mis->postcopy_prio_thread_mutex);
+ while (1) {
+ ret = ram_load_postcopy(mis->postcopy_qemufile_dst,
+ RAM_CHANNEL_POSTCOPY);
+ /* If error happened, go into recovery routine */
+ if (ret) {
+ postcopy_pause_ram_fast_load(mis);
+ } else {
+ /* We're done */
+ break;
+ }
+ }
+ qemu_mutex_unlock(&mis->postcopy_prio_thread_mutex);
rcu_unregister_thread();
trace_postcopy_preempt_thread_exit();
- return ret == 0 ? NULL : (void *)-1;
+ return NULL;
}
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 1e80d496b7..2f266b25cd 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -160,6 +160,33 @@ int qemu_file_get_error_obj(QEMUFile *f, Error **errp)
return f->last_error;
}
+/*
+ * Get last error for either stream f1 or f2 with optional Error*.
+ * The error returned (non-zero) can be either from f1 or f2.
+ *
+ * If any of the qemufile* is NULL, then skip the check on that file.
+ *
+ * When there is no error on both qemufile, zero is returned.
+ */
+int qemu_file_get_error_obj_any(QEMUFile *f1, QEMUFile *f2, Error **errp)
+{
+ int ret = 0;
+
+ if (f1) {
+ ret = qemu_file_get_error_obj(f1, errp);
+ /* If there's already error detected, return */
+ if (ret) {
+ return ret;
+ }
+ }
+
+ if (f2) {
+ ret = qemu_file_get_error_obj(f2, errp);
+ }
+
+ return ret;
+}
+
/*
* Set the last error for stream f with optional Error*
*/
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index 96e72d8bd8..fa13d04d78 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -141,6 +141,7 @@ void qemu_file_acct_rate_limit(QEMUFile *f, int64_t len);
void qemu_file_set_rate_limit(QEMUFile *f, int64_t new_rate);
int64_t qemu_file_get_rate_limit(QEMUFile *f);
int qemu_file_get_error_obj(QEMUFile *f, Error **errp);
+int qemu_file_get_error_obj_any(QEMUFile *f1, QEMUFile *f2, Error **errp);
void qemu_file_set_error_obj(QEMUFile *f, int ret, Error *err);
void qemu_file_set_error(QEMUFile *f, int ret);
int qemu_file_shutdown(QEMUFile *f);
diff --git a/migration/savevm.c b/migration/savevm.c
index e3af03cb9b..48e85c052c 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2117,6 +2117,13 @@ static int loadvm_postcopy_handle_resume(MigrationIncomingState *mis)
*/
qemu_sem_post(&mis->postcopy_pause_sem_fault);
+ if (migrate_postcopy_preempt()) {
+ /* The channel should already be setup again; make sure of it */
+ assert(mis->postcopy_qemufile_dst);
+ /* Kick the fast ram load thread too */
+ qemu_sem_post(&mis->postcopy_pause_sem_fast_load);
+ }
+
return 0;
}
@@ -2562,6 +2569,21 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
mis->to_src_file = NULL;
qemu_mutex_unlock(&mis->rp_mutex);
+ /*
+ * NOTE: this must happen before reset the PostcopyTmpPages below,
+ * otherwise it's racy to reset those fields when the fast load thread
+ * can be accessing it in parallel.
+ */
+ if (mis->postcopy_qemufile_dst) {
+ qemu_file_shutdown(mis->postcopy_qemufile_dst);
+ /* Take the mutex to make sure the fast ram load thread halted */
+ qemu_mutex_lock(&mis->postcopy_prio_thread_mutex);
+ migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
+ qemu_fclose(mis->postcopy_qemufile_dst);
+ mis->postcopy_qemufile_dst = NULL;
+ qemu_mutex_unlock(&mis->postcopy_prio_thread_mutex);
+ }
+
migrate_set_state(&mis->state, MIGRATION_STATUS_POSTCOPY_ACTIVE,
MIGRATION_STATUS_POSTCOPY_PAUSED);
@@ -2599,8 +2621,8 @@ retry:
while (true) {
section_type = qemu_get_byte(f);
- if (qemu_file_get_error(f)) {
- ret = qemu_file_get_error(f);
+ ret = qemu_file_get_error_obj_any(f, mis->postcopy_qemufile_dst, NULL);
+ if (ret) {
break;
}
diff --git a/migration/trace-events b/migration/trace-events
index 69f311169a..0e385c3a07 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -270,6 +270,8 @@ mark_postcopy_blocktime_begin(uint64_t addr, void *dd, uint32_t time, int cpu, i
mark_postcopy_blocktime_end(uint64_t addr, void *dd, uint32_t time, int affected_cpu) "addr: 0x%" PRIx64 ", dd: %p, time: %u, affected_cpu: %d"
postcopy_pause_fault_thread(void) ""
postcopy_pause_fault_thread_continued(void) ""
+postcopy_pause_fast_load(void) ""
+postcopy_pause_fast_load_continued(void) ""
postcopy_ram_fault_thread_entry(void) ""
postcopy_ram_fault_thread_exit(void) ""
postcopy_ram_fault_thread_fds_core(int baseufd, int quitfd) "ufd: %d quitfd: %d"
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 05/14] migration: Create the postcopy preempt channel asynchronously
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (3 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 04/14] migration: Postcopy recover with preempt enabled Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 06/14] migration: Add property x-postcopy-preempt-break-huge Peter Xu
` (9 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
This patch allows the postcopy preempt channel to be created
asynchronously. The benefit is that when the connection is slow, we won't
take the BQL (and potentially block all things like QMP) for a long time
without releasing.
A function postcopy_preempt_wait_channel() is introduced, allowing the
migration thread to be able to wait on the channel creation. The channel
is always created by the main thread, in which we'll kick a new semaphore
to tell the migration thread that the channel has created.
We'll need to wait for the new channel in two places: (1) when there's a
new postcopy migration that is starting, or (2) when there's a postcopy
migration to resume.
For the start of migration, we don't need to wait for this channel until
when we want to start postcopy, aka, postcopy_start(). We'll fail the
migration if we found that the channel creation failed (which should
probably not happen at all in 99% of the cases, because the main channel is
using the same network topology).
For a postcopy recovery, we'll need to wait in postcopy_pause(). In that
case if the channel creation failed, we can't fail the migration or we'll
crash the VM, instead we keep in PAUSED state, waiting for yet another
recovery.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Manish Mishra <manish.mishra@nutanix.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 16 ++++++++++++
migration/migration.h | 7 +++++
migration/postcopy-ram.c | 56 +++++++++++++++++++++++++++++++---------
migration/postcopy-ram.h | 1 +
4 files changed, 68 insertions(+), 12 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index db82ecbdcd..5d113bd5cc 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3052,6 +3052,12 @@ static int postcopy_start(MigrationState *ms)
int64_t bandwidth = migrate_max_postcopy_bandwidth();
bool restart_block = false;
int cur_state = MIGRATION_STATUS_ACTIVE;
+
+ if (postcopy_preempt_wait_channel(ms)) {
+ migrate_set_state(&ms->state, ms->state, MIGRATION_STATUS_FAILED);
+ return -1;
+ }
+
if (!migrate_pause_before_switchover()) {
migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_POSTCOPY_ACTIVE);
@@ -3533,6 +3539,14 @@ static MigThrError postcopy_pause(MigrationState *s)
if (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) {
/* Woken up by a recover procedure. Give it a shot */
+ if (postcopy_preempt_wait_channel(s)) {
+ /*
+ * Preempt enabled, and new channel create failed; loop
+ * back to wait for another recovery.
+ */
+ continue;
+ }
+
/*
* Firstly, let's wake up the return path now, with a new
* return path channel.
@@ -4397,6 +4411,7 @@ static void migration_instance_finalize(Object *obj)
qemu_sem_destroy(&ms->postcopy_pause_sem);
qemu_sem_destroy(&ms->postcopy_pause_rp_sem);
qemu_sem_destroy(&ms->rp_state.rp_sem);
+ qemu_sem_destroy(&ms->postcopy_qemufile_src_sem);
error_free(ms->error);
}
@@ -4443,6 +4458,7 @@ static void migration_instance_init(Object *obj)
qemu_sem_init(&ms->rp_state.rp_sem, 0);
qemu_sem_init(&ms->rate_limit_sem, 0);
qemu_sem_init(&ms->wait_unplug_sem, 0);
+ qemu_sem_init(&ms->postcopy_qemufile_src_sem, 0);
qemu_mutex_init(&ms->qemu_file_lock);
}
diff --git a/migration/migration.h b/migration/migration.h
index 9220cec6bd..ae4ffd3454 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -219,6 +219,13 @@ struct MigrationState {
QEMUFile *to_dst_file;
/* Postcopy specific transfer channel */
QEMUFile *postcopy_qemufile_src;
+ /*
+ * It is posted when the preempt channel is established. Note: this is
+ * used for both the start or recover of a postcopy migration. We'll
+ * post to this sem every time a new preempt channel is created in the
+ * main thread, and we keep post() and wait() in pair.
+ */
+ QemuSemaphore postcopy_qemufile_src_sem;
QIOChannelBuffer *bioc;
/*
* Protects to_dst_file/from_dst_file pointers. We need to make sure we
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 84f7b1526e..70b21e9d51 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1552,10 +1552,50 @@ bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
return true;
}
-int postcopy_preempt_setup(MigrationState *s, Error **errp)
+static void
+postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
{
- QIOChannel *ioc;
+ MigrationState *s = opaque;
+ QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
+ Error *local_err = NULL;
+
+ if (qio_task_propagate_error(task, &local_err)) {
+ /* Something wrong happened.. */
+ migrate_set_error(s, local_err);
+ error_free(local_err);
+ } else {
+ migration_ioc_register_yank(ioc);
+ s->postcopy_qemufile_src = qemu_file_new_output(ioc);
+ trace_postcopy_preempt_new_channel();
+ }
+
+ /*
+ * Kick the waiter in all cases. The waiter should check upon
+ * postcopy_qemufile_src to know whether it failed or not.
+ */
+ qemu_sem_post(&s->postcopy_qemufile_src_sem);
+ object_unref(OBJECT(ioc));
+}
+/* Returns 0 if channel established, -1 for error. */
+int postcopy_preempt_wait_channel(MigrationState *s)
+{
+ /* If preempt not enabled, no need to wait */
+ if (!migrate_postcopy_preempt()) {
+ return 0;
+ }
+
+ /*
+ * We need the postcopy preempt channel to be established before
+ * starting doing anything.
+ */
+ qemu_sem_wait(&s->postcopy_qemufile_src_sem);
+
+ return s->postcopy_qemufile_src ? 0 : -1;
+}
+
+int postcopy_preempt_setup(MigrationState *s, Error **errp)
+{
if (!migrate_postcopy_preempt()) {
return 0;
}
@@ -1566,16 +1606,8 @@ int postcopy_preempt_setup(MigrationState *s, Error **errp)
return -1;
}
- ioc = socket_send_channel_create_sync(errp);
-
- if (ioc == NULL) {
- return -1;
- }
-
- migration_ioc_register_yank(ioc);
- s->postcopy_qemufile_src = qemu_file_new_output(ioc);
-
- trace_postcopy_preempt_new_channel();
+ /* Kick an async task to connect */
+ socket_send_channel_create(postcopy_preempt_send_channel_new, s);
return 0;
}
diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index 34b1080cde..6147bf7d1d 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -192,5 +192,6 @@ enum PostcopyChannels {
bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
int postcopy_preempt_setup(MigrationState *s, Error **errp);
+int postcopy_preempt_wait_channel(MigrationState *s);
#endif
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 06/14] migration: Add property x-postcopy-preempt-break-huge
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (4 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 05/14] migration: Create the postcopy preempt channel asynchronously Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 07/14] migration: Add helpers to detect TLS capability Peter Xu
` (8 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
Add a property field that can conditionally disable the "break sending huge
page" behavior in postcopy preemption. By default it's enabled.
It should only be used for debugging purposes, and we should never remove
the "x-" prefix.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Manish Mishra <manish.mishra@nutanix.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 2 ++
migration/migration.h | 7 +++++++
migration/ram.c | 7 +++++++
3 files changed, 16 insertions(+)
diff --git a/migration/migration.c b/migration/migration.c
index 5d113bd5cc..e10f0400ef 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -4362,6 +4362,8 @@ static Property migration_properties[] = {
DEFINE_PROP_SIZE("announce-step", MigrationState,
parameters.announce_step,
DEFAULT_MIGRATE_ANNOUNCE_STEP),
+ DEFINE_PROP_BOOL("x-postcopy-preempt-break-huge", MigrationState,
+ postcopy_preempt_break_huge, true),
/* Migration capabilities */
DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
diff --git a/migration/migration.h b/migration/migration.h
index ae4ffd3454..cdad8aceaa 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -340,6 +340,13 @@ struct MigrationState {
bool send_configuration;
/* Whether we send section footer during migration */
bool send_section_footer;
+ /*
+ * Whether we allow break sending huge pages when postcopy preempt is
+ * enabled. When disabled, we won't interrupt precopy within sending a
+ * host huge page, which is the old behavior of vanilla postcopy.
+ * NOTE: this parameter is ignored if postcopy preempt is not enabled.
+ */
+ bool postcopy_preempt_break_huge;
/* Needed by postcopy-pause state */
QemuSemaphore postcopy_pause_sem;
diff --git a/migration/ram.c b/migration/ram.c
index 65b08c4edb..7cbe9c310d 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2266,11 +2266,18 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss)
static bool postcopy_needs_preempt(RAMState *rs, PageSearchStatus *pss)
{
+ MigrationState *ms = migrate_get_current();
+
/* Not enabled eager preempt? Then never do that. */
if (!migrate_postcopy_preempt()) {
return false;
}
+ /* If the user explicitly disabled breaking of huge page, skip */
+ if (!ms->postcopy_preempt_break_huge) {
+ return false;
+ }
+
/* If the ramblock we're sending is a small page? Never bother. */
if (qemu_ram_pagesize(pss->block) == TARGET_PAGE_SIZE) {
return false;
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 07/14] migration: Add helpers to detect TLS capability
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (5 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 06/14] migration: Add property x-postcopy-preempt-break-huge Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 08/14] migration: Export tls-[creds|hostname|authz] params to cmdline too Peter Xu
` (7 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
Add migrate_channel_requires_tls() to detect whether the specific channel
requires TLS, leveraging the recently introduced migrate_use_tls(). No
functional change intended.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/channel.c | 9 ++-------
migration/migration.c | 1 +
migration/multifd.c | 4 +---
migration/tls.c | 9 +++++++++
migration/tls.h | 4 ++++
5 files changed, 17 insertions(+), 10 deletions(-)
diff --git a/migration/channel.c b/migration/channel.c
index 90087d8986..1b0815039f 100644
--- a/migration/channel.c
+++ b/migration/channel.c
@@ -38,9 +38,7 @@ void migration_channel_process_incoming(QIOChannel *ioc)
trace_migration_set_incoming_channel(
ioc, object_get_typename(OBJECT(ioc)));
- if (migrate_use_tls() &&
- !object_dynamic_cast(OBJECT(ioc),
- TYPE_QIO_CHANNEL_TLS)) {
+ if (migrate_channel_requires_tls_upgrade(ioc)) {
migration_tls_channel_process_incoming(s, ioc, &local_err);
} else {
migration_ioc_register_yank(ioc);
@@ -70,10 +68,7 @@ void migration_channel_connect(MigrationState *s,
ioc, object_get_typename(OBJECT(ioc)), hostname, error);
if (!error) {
- if (s->parameters.tls_creds &&
- *s->parameters.tls_creds &&
- !object_dynamic_cast(OBJECT(ioc),
- TYPE_QIO_CHANNEL_TLS)) {
+ if (migrate_channel_requires_tls_upgrade(ioc)) {
migration_tls_channel_connect(s, ioc, hostname, &error);
if (!error) {
diff --git a/migration/migration.c b/migration/migration.c
index e10f0400ef..fe77c7d0ef 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -48,6 +48,7 @@
#include "trace.h"
#include "exec/target_page.h"
#include "io/channel-buffer.h"
+#include "io/channel-tls.h"
#include "migration/colo.h"
#include "hw/boards.h"
#include "hw/qdev-properties.h"
diff --git a/migration/multifd.c b/migration/multifd.c
index 684c014c86..1e49594b02 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -831,9 +831,7 @@ static bool multifd_channel_connect(MultiFDSendParams *p,
migrate_get_current()->hostname, error);
if (!error) {
- if (migrate_use_tls() &&
- !object_dynamic_cast(OBJECT(ioc),
- TYPE_QIO_CHANNEL_TLS)) {
+ if (migrate_channel_requires_tls_upgrade(ioc)) {
multifd_tls_channel_connect(p, ioc, &error);
if (!error) {
/*
diff --git a/migration/tls.c b/migration/tls.c
index 32c384a8b6..73e8c9d3c2 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -166,3 +166,12 @@ void migration_tls_channel_connect(MigrationState *s,
NULL,
NULL);
}
+
+bool migrate_channel_requires_tls_upgrade(QIOChannel *ioc)
+{
+ if (!migrate_use_tls()) {
+ return false;
+ }
+
+ return !object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_TLS);
+}
diff --git a/migration/tls.h b/migration/tls.h
index de4fe2cafd..98e23c9b0e 100644
--- a/migration/tls.h
+++ b/migration/tls.h
@@ -37,4 +37,8 @@ void migration_tls_channel_connect(MigrationState *s,
QIOChannel *ioc,
const char *hostname,
Error **errp);
+
+/* Whether the QIO channel requires further TLS handshake? */
+bool migrate_channel_requires_tls_upgrade(QIOChannel *ioc);
+
#endif
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 08/14] migration: Export tls-[creds|hostname|authz] params to cmdline too
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (6 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 07/14] migration: Add helpers to detect TLS capability Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 09/14] migration: Enable TLS for preempt channel Peter Xu
` (6 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
It's useful for specifying tls credentials all in the cmdline (along with
the -object tls-creds-*), especially for debugging purpose.
The trick here is we must remember to not free these fields again in the
finalize() function of migration object, otherwise it'll cause double-free.
The thing is when destroying an object, we'll first destroy the properties
that bound to the object, then the object itself. To be explicit, when
destroy the object in object_finalize() we have such sequence of
operations:
object_property_del_all(obj);
object_deinit(obj, ti);
So after this change the two fields are properly released already even
before reaching the finalize() function but in object_property_del_all(),
hence we don't need to free them anymore in finalize() or it's double-free.
This also fixes a trivial memory leak for tls-authz as we forgot to free it
before this patch.
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/migration/migration.c b/migration/migration.c
index fe77c7d0ef..76cf2a72c0 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -4365,6 +4365,9 @@ static Property migration_properties[] = {
DEFAULT_MIGRATE_ANNOUNCE_STEP),
DEFINE_PROP_BOOL("x-postcopy-preempt-break-huge", MigrationState,
postcopy_preempt_break_huge, true),
+ DEFINE_PROP_STRING("tls-creds", MigrationState, parameters.tls_creds),
+ DEFINE_PROP_STRING("tls-hostname", MigrationState, parameters.tls_hostname),
+ DEFINE_PROP_STRING("tls-authz", MigrationState, parameters.tls_authz),
/* Migration capabilities */
DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
@@ -4402,12 +4405,9 @@ static void migration_class_init(ObjectClass *klass, void *data)
static void migration_instance_finalize(Object *obj)
{
MigrationState *ms = MIGRATION_OBJ(obj);
- MigrationParameters *params = &ms->parameters;
qemu_mutex_destroy(&ms->error_mutex);
qemu_mutex_destroy(&ms->qemu_file_lock);
- g_free(params->tls_hostname);
- g_free(params->tls_creds);
qemu_sem_destroy(&ms->wait_unplug_sem);
qemu_sem_destroy(&ms->rate_limit_sem);
qemu_sem_destroy(&ms->pause_sem);
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 09/14] migration: Enable TLS for preempt channel
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (7 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 08/14] migration: Export tls-[creds|hostname|authz] params to cmdline too Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 10/14] migration: Respect postcopy request order in preemption mode Peter Xu
` (5 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
This patch is based on the async preempt channel creation. It continues
wiring up the new channel with TLS handshake to destionation when enabled.
Note that only the src QEMU needs such operation; the dest QEMU does not
need any change for TLS support due to the fact that all channels are
established synchronously there, so all the TLS magic is already properly
handled by migration_tls_channel_process_incoming().
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/postcopy-ram.c | 57 ++++++++++++++++++++++++++++++++++------
migration/trace-events | 1 +
2 files changed, 50 insertions(+), 8 deletions(-)
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 70b21e9d51..b9a37ef255 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -36,6 +36,7 @@
#include "socket.h"
#include "qemu-file.h"
#include "yank_functions.h"
+#include "tls.h"
/* Arbitrary limit on size of each discard command,
* keeps them around ~200 bytes
@@ -1552,15 +1553,15 @@ bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
return true;
}
+/*
+ * Setup the postcopy preempt channel with the IOC. If ERROR is specified,
+ * setup the error instead. This helper will free the ERROR if specified.
+ */
static void
-postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
+postcopy_preempt_send_channel_done(MigrationState *s,
+ QIOChannel *ioc, Error *local_err)
{
- MigrationState *s = opaque;
- QIOChannel *ioc = QIO_CHANNEL(qio_task_get_source(task));
- Error *local_err = NULL;
-
- if (qio_task_propagate_error(task, &local_err)) {
- /* Something wrong happened.. */
+ if (local_err) {
migrate_set_error(s, local_err);
error_free(local_err);
} else {
@@ -1574,7 +1575,47 @@ postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
* postcopy_qemufile_src to know whether it failed or not.
*/
qemu_sem_post(&s->postcopy_qemufile_src_sem);
- object_unref(OBJECT(ioc));
+}
+
+static void
+postcopy_preempt_tls_handshake(QIOTask *task, gpointer opaque)
+{
+ g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
+ MigrationState *s = opaque;
+ Error *local_err = NULL;
+
+ qio_task_propagate_error(task, &local_err);
+ postcopy_preempt_send_channel_done(s, ioc, local_err);
+}
+
+static void
+postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
+{
+ g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
+ MigrationState *s = opaque;
+ QIOChannelTLS *tioc;
+ Error *local_err = NULL;
+
+ if (qio_task_propagate_error(task, &local_err)) {
+ goto out;
+ }
+
+ if (migrate_channel_requires_tls_upgrade(ioc)) {
+ tioc = migration_tls_client_create(s, ioc, s->hostname, &local_err);
+ if (!tioc) {
+ goto out;
+ }
+ trace_postcopy_preempt_tls_handshake();
+ qio_channel_set_name(QIO_CHANNEL(tioc), "migration-tls-preempt");
+ qio_channel_tls_handshake(tioc, postcopy_preempt_tls_handshake,
+ s, NULL, NULL);
+ /* Setup the channel until TLS handshake finished */
+ return;
+ }
+
+out:
+ /* This handles both good and error cases */
+ postcopy_preempt_send_channel_done(s, ioc, local_err);
}
/* Returns 0 if channel established, -1 for error. */
diff --git a/migration/trace-events b/migration/trace-events
index 0e385c3a07..a34afe7b85 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -287,6 +287,7 @@ postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_off
postcopy_request_shared_page_present(const char *sharer, const char *rb, uint64_t rb_offset) "%s already %s offset 0x%"PRIx64
postcopy_wake_shared(uint64_t client_addr, const char *rb) "at 0x%"PRIx64" in %s"
postcopy_page_req_del(void *addr, int count) "resolved page req %p total %d"
+postcopy_preempt_tls_handshake(void) ""
postcopy_preempt_new_channel(void) ""
postcopy_preempt_thread_entry(void) ""
postcopy_preempt_thread_exit(void) ""
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 10/14] migration: Respect postcopy request order in preemption mode
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (8 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 09/14] migration: Enable TLS for preempt channel Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 11/14] tests: Move MigrateCommon upper Peter Xu
` (4 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
With preemption mode on, when we see a postcopy request that was requesting
for exactly the page that we have preempted before (so we've partially sent
the page already via PRECOPY channel and it got preempted by another
postcopy request), currently we drop the request so that after all the
other postcopy requests are serviced then we'll go back to precopy stream
and start to handle that.
We dropped the request because we can't send it via postcopy channel since
the precopy channel already contains partial of the data, and we can only
send a huge page via one channel as a whole. We can't split a huge page
into two channels.
That's a very corner case and that works, but there's a change on the order
of postcopy requests that we handle since we're postponing this (unlucky)
postcopy request to be later than the other queued postcopy requests. The
problem is there's a possibility that when the guest was very busy, the
postcopy queue can be always non-empty, it means this dropped request will
never be handled until the end of postcopy migration. So, there's a chance
that there's one dest QEMU vcpu thread waiting for a page fault for an
extremely long time just because it's unluckily accessing the specific page
that was preempted before.
The worst case time it needs can be as long as the whole postcopy migration
procedure. It's extremely unlikely to happen, but when it happens it's not
good.
The root cause of this problem is because we treat pss->postcopy_requested
variable as with two meanings bound together, as the variable shows:
1. Whether this page request is urgent, and,
2. Which channel we should use for this page request.
With the old code, when we set postcopy_requested it means either both (1)
and (2) are true, or both (1) and (2) are false. We can never have (1)
and (2) to have different values.
However it doesn't necessarily need to be like that. It's very legal that
there's one request that has (1) very high urgency, but (2) we'd like to
use the precopy channel. Just like the corner case we were discussing
above.
To differenciate the two meanings better, introduce a new field called
postcopy_target_channel, showing which channel we should use for this page
request, so as to cover the old meaning (2) only. Then we leave the
postcopy_requested variable to stand only for meaning (1), which is the
urgency of this page request.
With this change, we can easily boost priority of a preempted precopy page
as long as we know that page is also requested as a postcopy page. So with
the new approach in get_queued_page() instead of dropping that request, we
send it right away with the precopy channel so we get back the ordering of
the page faults just like how they're requested on dest.
Reported-by: Manish Mishra <manish.mishra@nutanix.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Manish Mishra <manish.mishra@nutanix.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/ram.c | 65 +++++++++++++++++++++++++++++++++++++++----------
1 file changed, 52 insertions(+), 13 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 7cbe9c310d..4fbad74c6c 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -442,8 +442,28 @@ struct PageSearchStatus {
unsigned long page;
/* Set once we wrap around */
bool complete_round;
- /* Whether current page is explicitly requested by postcopy */
+ /*
+ * [POSTCOPY-ONLY] Whether current page is explicitly requested by
+ * postcopy. When set, the request is "urgent" because the dest QEMU
+ * threads are waiting for us.
+ */
bool postcopy_requested;
+ /*
+ * [POSTCOPY-ONLY] The target channel to use to send current page.
+ *
+ * Note: This may _not_ match with the value in postcopy_requested
+ * above. Let's imagine the case where the postcopy request is exactly
+ * the page that we're sending in progress during precopy. In this case
+ * we'll have postcopy_requested set to true but the target channel
+ * will be the precopy channel (so that we don't split brain on that
+ * specific page since the precopy channel already contains partial of
+ * that page data).
+ *
+ * Besides that specific use case, postcopy_target_channel should
+ * always be equal to postcopy_requested, because by default we send
+ * postcopy pages via postcopy preempt channel.
+ */
+ bool postcopy_target_channel;
};
typedef struct PageSearchStatus PageSearchStatus;
@@ -495,6 +515,9 @@ static QemuCond decomp_done_cond;
static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock *block,
ram_addr_t offset, uint8_t *source_buf);
+static void postcopy_preempt_restore(RAMState *rs, PageSearchStatus *pss,
+ bool postcopy_requested);
+
static void *do_data_compress(void *opaque)
{
CompressParam *param = opaque;
@@ -1516,8 +1539,12 @@ retry:
*/
static bool find_dirty_block(RAMState *rs, PageSearchStatus *pss, bool *again)
{
- /* This is not a postcopy requested page */
+ /*
+ * This is not a postcopy requested page, mark it "not urgent", and use
+ * precopy channel to send it.
+ */
pss->postcopy_requested = false;
+ pss->postcopy_target_channel = RAM_CHANNEL_PRECOPY;
pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page);
if (pss->complete_round && pss->block == rs->last_seen_block &&
@@ -2038,15 +2065,20 @@ static bool get_queued_page(RAMState *rs, PageSearchStatus *pss)
RAMBlock *block;
ram_addr_t offset;
-again:
block = unqueue_page(rs, &offset);
if (block) {
/* See comment above postcopy_preempted_contains() */
if (postcopy_preempted_contains(rs, block, offset)) {
trace_postcopy_preempt_hit(block->idstr, offset);
- /* This request is dropped */
- goto again;
+ /*
+ * If what we preempted previously was exactly what we're
+ * requesting right now, restore the preempted precopy
+ * immediately, boosting its priority as it's requested by
+ * postcopy.
+ */
+ postcopy_preempt_restore(rs, pss, true);
+ return true;
}
} else {
/*
@@ -2070,7 +2102,9 @@ again:
* really rare.
*/
pss->complete_round = false;
+ /* Mark it an urgent request, meanwhile using POSTCOPY channel */
pss->postcopy_requested = true;
+ pss->postcopy_target_channel = RAM_CHANNEL_POSTCOPY;
}
return !!block;
@@ -2324,7 +2358,8 @@ static bool postcopy_preempt_triggered(RAMState *rs)
return rs->postcopy_preempt_state.preempted;
}
-static void postcopy_preempt_restore(RAMState *rs, PageSearchStatus *pss)
+static void postcopy_preempt_restore(RAMState *rs, PageSearchStatus *pss,
+ bool postcopy_requested)
{
PostcopyPreemptState *state = &rs->postcopy_preempt_state;
@@ -2332,8 +2367,15 @@ static void postcopy_preempt_restore(RAMState *rs, PageSearchStatus *pss)
pss->block = state->ram_block;
pss->page = state->ram_page;
- /* This is not a postcopy request but restoring previous precopy */
- pss->postcopy_requested = false;
+
+ /* Whether this is a postcopy request? */
+ pss->postcopy_requested = postcopy_requested;
+ /*
+ * When restoring a preempted page, the old data resides in PRECOPY
+ * slow channel, even if postcopy_requested is set. So always use
+ * PRECOPY channel here.
+ */
+ pss->postcopy_target_channel = RAM_CHANNEL_PRECOPY;
trace_postcopy_preempt_restored(pss->block->idstr, pss->page);
@@ -2344,12 +2386,9 @@ static void postcopy_preempt_restore(RAMState *rs, PageSearchStatus *pss)
static void postcopy_preempt_choose_channel(RAMState *rs, PageSearchStatus *pss)
{
MigrationState *s = migrate_get_current();
- unsigned int channel;
+ unsigned int channel = pss->postcopy_target_channel;
QEMUFile *next;
- channel = pss->postcopy_requested ?
- RAM_CHANNEL_POSTCOPY : RAM_CHANNEL_PRECOPY;
-
if (channel != rs->postcopy_channel) {
if (channel == RAM_CHANNEL_PRECOPY) {
next = s->to_dst_file;
@@ -2505,7 +2544,7 @@ static int ram_find_and_save_block(RAMState *rs)
* preempted precopy. Otherwise find the next dirty bit.
*/
if (postcopy_preempt_triggered(rs)) {
- postcopy_preempt_restore(rs, &pss);
+ postcopy_preempt_restore(rs, &pss, false);
found = true;
} else {
/* priority queue empty, so just search for something dirty */
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 11/14] tests: Move MigrateCommon upper
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (9 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 10/14] migration: Respect postcopy request order in preemption mode Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 12/14] tests: Add postcopy tls migration test Peter Xu
` (3 subsequent siblings)
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
So that it can be used in postcopy tests too soon.
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
tests/qtest/migration-test.c | 144 +++++++++++++++++------------------
1 file changed, 72 insertions(+), 72 deletions(-)
diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index 55acf9612c..f15a7517b1 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -496,6 +496,78 @@ typedef struct {
const char *opts_target;
} MigrateStart;
+/*
+ * A hook that runs after the src and dst QEMUs have been
+ * created, but before the migration is started. This can
+ * be used to set migration parameters and capabilities.
+ *
+ * Returns: NULL, or a pointer to opaque state to be
+ * later passed to the TestMigrateFinishHook
+ */
+typedef void * (*TestMigrateStartHook)(QTestState *from,
+ QTestState *to);
+
+/*
+ * A hook that runs after the migration has finished,
+ * regardless of whether it succeeded or failed, but
+ * before QEMU has terminated (unless it self-terminated
+ * due to migration error)
+ *
+ * @opaque is a pointer to state previously returned
+ * by the TestMigrateStartHook if any, or NULL.
+ */
+typedef void (*TestMigrateFinishHook)(QTestState *from,
+ QTestState *to,
+ void *opaque);
+
+typedef struct {
+ /* Optional: fine tune start parameters */
+ MigrateStart start;
+
+ /* Required: the URI for the dst QEMU to listen on */
+ const char *listen_uri;
+
+ /*
+ * Optional: the URI for the src QEMU to connect to
+ * If NULL, then it will query the dst QEMU for its actual
+ * listening address and use that as the connect address.
+ * This allows for dynamically picking a free TCP port.
+ */
+ const char *connect_uri;
+
+ /* Optional: callback to run at start to set migration parameters */
+ TestMigrateStartHook start_hook;
+ /* Optional: callback to run at finish to cleanup */
+ TestMigrateFinishHook finish_hook;
+
+ /*
+ * Optional: normally we expect the migration process to complete.
+ *
+ * There can be a variety of reasons and stages in which failure
+ * can happen during tests.
+ *
+ * If a failure is expected to happen at time of establishing
+ * the connection, then MIG_TEST_FAIL will indicate that the dst
+ * QEMU is expected to stay running and accept future migration
+ * connections.
+ *
+ * If a failure is expected to happen while processing the
+ * migration stream, then MIG_TEST_FAIL_DEST_QUIT_ERR will indicate
+ * that the dst QEMU is expected to quit with non-zero exit status
+ */
+ enum {
+ /* This test should succeed, the default */
+ MIG_TEST_SUCCEED = 0,
+ /* This test should fail, dest qemu should keep alive */
+ MIG_TEST_FAIL,
+ /* This test should fail, dest qemu should fail with abnormal status */
+ MIG_TEST_FAIL_DEST_QUIT_ERR,
+ } result;
+
+ /* Optional: set number of migration passes to wait for */
+ unsigned int iterations;
+} MigrateCommon;
+
static int test_migrate_start(QTestState **from, QTestState **to,
const char *uri, MigrateStart *args)
{
@@ -1113,78 +1185,6 @@ static void test_baddest(void)
test_migrate_end(from, to, false);
}
-/*
- * A hook that runs after the src and dst QEMUs have been
- * created, but before the migration is started. This can
- * be used to set migration parameters and capabilities.
- *
- * Returns: NULL, or a pointer to opaque state to be
- * later passed to the TestMigrateFinishHook
- */
-typedef void * (*TestMigrateStartHook)(QTestState *from,
- QTestState *to);
-
-/*
- * A hook that runs after the migration has finished,
- * regardless of whether it succeeded or failed, but
- * before QEMU has terminated (unless it self-terminated
- * due to migration error)
- *
- * @opaque is a pointer to state previously returned
- * by the TestMigrateStartHook if any, or NULL.
- */
-typedef void (*TestMigrateFinishHook)(QTestState *from,
- QTestState *to,
- void *opaque);
-
-typedef struct {
- /* Optional: fine tune start parameters */
- MigrateStart start;
-
- /* Required: the URI for the dst QEMU to listen on */
- const char *listen_uri;
-
- /*
- * Optional: the URI for the src QEMU to connect to
- * If NULL, then it will query the dst QEMU for its actual
- * listening address and use that as the connect address.
- * This allows for dynamically picking a free TCP port.
- */
- const char *connect_uri;
-
- /* Optional: callback to run at start to set migration parameters */
- TestMigrateStartHook start_hook;
- /* Optional: callback to run at finish to cleanup */
- TestMigrateFinishHook finish_hook;
-
- /*
- * Optional: normally we expect the migration process to complete.
- *
- * There can be a variety of reasons and stages in which failure
- * can happen during tests.
- *
- * If a failure is expected to happen at time of establishing
- * the connection, then MIG_TEST_FAIL will indicate that the dst
- * QEMU is expected to stay running and accept future migration
- * connections.
- *
- * If a failure is expected to happen while processing the
- * migration stream, then MIG_TEST_FAIL_DEST_QUIT_ERR will indicate
- * that the dst QEMU is expected to quit with non-zero exit status
- */
- enum {
- /* This test should succeed, the default */
- MIG_TEST_SUCCEED = 0,
- /* This test should fail, dest qemu should keep alive */
- MIG_TEST_FAIL,
- /* This test should fail, dest qemu should fail with abnormal status */
- MIG_TEST_FAIL_DEST_QUIT_ERR,
- } result;
-
- /* Optional: set number of migration passes to wait for */
- unsigned int iterations;
-} MigrateCommon;
-
static void test_precopy_common(MigrateCommon *args)
{
QTestState *from, *to;
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 12/14] tests: Add postcopy tls migration test
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (10 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 11/14] tests: Move MigrateCommon upper Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-13 11:25 ` Dr. David Alan Gilbert
2022-07-07 18:55 ` [PATCH v9 13/14] tests: Add postcopy tls recovery " Peter Xu
` (2 subsequent siblings)
14 siblings, 1 reply; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
We just added TLS tests for precopy but not postcopy. Add the
corresponding test for vanilla postcopy.
Rename the vanilla postcopy to "postcopy/plain" because all postcopy tests
will only use unix sockets as channel.
Signed-off-by: Peter Xu <peterx@redhat.com>
---
tests/qtest/migration-test.c | 61 ++++++++++++++++++++++++++++++------
1 file changed, 51 insertions(+), 10 deletions(-)
diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index f15a7517b1..ee37ad6631 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -566,6 +566,9 @@ typedef struct {
/* Optional: set number of migration passes to wait for */
unsigned int iterations;
+
+ /* Postcopy specific fields */
+ void *postcopy_data;
} MigrateCommon;
static int test_migrate_start(QTestState **from, QTestState **to,
@@ -1054,15 +1057,19 @@ test_migrate_tls_x509_finish(QTestState *from,
static int migrate_postcopy_prepare(QTestState **from_ptr,
QTestState **to_ptr,
- MigrateStart *args)
+ MigrateCommon *args)
{
g_autofree char *uri = g_strdup_printf("unix:%s/migsocket", tmpfs);
QTestState *from, *to;
- if (test_migrate_start(&from, &to, uri, args)) {
+ if (test_migrate_start(&from, &to, uri, &args->start)) {
return -1;
}
+ if (args->start_hook) {
+ args->postcopy_data = args->start_hook(from, to);
+ }
+
migrate_set_capability(from, "postcopy-ram", true);
migrate_set_capability(to, "postcopy-ram", true);
migrate_set_capability(to, "postcopy-blocktime", true);
@@ -1082,7 +1089,8 @@ static int migrate_postcopy_prepare(QTestState **from_ptr,
return 0;
}
-static void migrate_postcopy_complete(QTestState *from, QTestState *to)
+static void migrate_postcopy_complete(QTestState *from, QTestState *to,
+ MigrateCommon *args)
{
wait_for_migration_complete(from);
@@ -1093,25 +1101,48 @@ static void migrate_postcopy_complete(QTestState *from, QTestState *to)
read_blocktime(to);
}
+ if (args->finish_hook) {
+ args->finish_hook(from, to, args->postcopy_data);
+ args->postcopy_data = NULL;
+ }
+
test_migrate_end(from, to, true);
}
-static void test_postcopy(void)
+static void test_postcopy_common(MigrateCommon *args)
{
- MigrateStart args = {};
QTestState *from, *to;
- if (migrate_postcopy_prepare(&from, &to, &args)) {
+ if (migrate_postcopy_prepare(&from, &to, args)) {
return;
}
migrate_postcopy_start(from, to);
- migrate_postcopy_complete(from, to);
+ migrate_postcopy_complete(from, to, args);
+}
+
+static void test_postcopy(void)
+{
+ MigrateCommon args = { };
+
+ test_postcopy_common(&args);
+}
+
+static void test_postcopy_tls_psk(void)
+{
+ MigrateCommon args = {
+ .start_hook = test_migrate_tls_psk_start_match,
+ .finish_hook = test_migrate_tls_psk_finish,
+ };
+
+ test_postcopy_common(&args);
}
static void test_postcopy_recovery(void)
{
- MigrateStart args = {
- .hide_stderr = true,
+ MigrateCommon args = {
+ .start = {
+ .hide_stderr = true,
+ },
};
QTestState *from, *to;
g_autofree char *uri = NULL;
@@ -1167,7 +1198,7 @@ static void test_postcopy_recovery(void)
/* Restore the postcopy bandwidth to unlimited */
migrate_set_parameter_int(from, "max-postcopy-bandwidth", 0);
- migrate_postcopy_complete(from, to);
+ migrate_postcopy_complete(from, to, &args);
}
static void test_baddest(void)
@@ -2122,6 +2153,16 @@ int main(int argc, char **argv)
if (has_uffd) {
qtest_add_func("/migration/postcopy/unix", test_postcopy);
qtest_add_func("/migration/postcopy/recovery", test_postcopy_recovery);
+ qtest_add_func("/migration/postcopy/plain", test_postcopy);
+#ifdef CONFIG_GNUTLS
+ /*
+ * NOTE: psk test is enough for postcopy, as other types of TLS
+ * channels are tested under precopy. Here what we want to test is the
+ * general postcopy path that has TLS channel enabled.
+ */
+ qtest_add_func("/migration/postcopy/tls/psk", test_postcopy_tls_psk);
+#endif /* CONFIG_GNUTLS */
+ qtest_add_func("/migration/postcopy/recovery", test_postcopy_recovery);
}
qtest_add_func("/migration/bad_dest", test_baddest);
qtest_add_func("/migration/precopy/unix/plain", test_precopy_unix_plain);
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 13/14] tests: Add postcopy tls recovery migration test
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (11 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 12/14] tests: Add postcopy tls migration test Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-07 18:55 ` [PATCH v9 14/14] tests: Add postcopy preempt tests Peter Xu
2022-07-19 13:50 ` [PATCH v9 00/14] migration: Postcopy Preemption Dr. David Alan Gilbert
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
It's easy to build this upon the postcopy tls test. Rename the old
postcopy recovery test to postcopy/recovery/plain.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
tests/qtest/migration-test.c | 37 ++++++++++++++++++++++++++++--------
1 file changed, 29 insertions(+), 8 deletions(-)
diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index ee37ad6631..81ef9741cd 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -1137,17 +1137,15 @@ static void test_postcopy_tls_psk(void)
test_postcopy_common(&args);
}
-static void test_postcopy_recovery(void)
+static void test_postcopy_recovery_common(MigrateCommon *args)
{
- MigrateCommon args = {
- .start = {
- .hide_stderr = true,
- },
- };
QTestState *from, *to;
g_autofree char *uri = NULL;
- if (migrate_postcopy_prepare(&from, &to, &args)) {
+ /* Always hide errors for postcopy recover tests since they're expected */
+ args->start.hide_stderr = true;
+
+ if (migrate_postcopy_prepare(&from, &to, args)) {
return;
}
@@ -1198,7 +1196,24 @@ static void test_postcopy_recovery(void)
/* Restore the postcopy bandwidth to unlimited */
migrate_set_parameter_int(from, "max-postcopy-bandwidth", 0);
- migrate_postcopy_complete(from, to, &args);
+ migrate_postcopy_complete(from, to, args);
+}
+
+static void test_postcopy_recovery(void)
+{
+ MigrateCommon args = { };
+
+ test_postcopy_recovery_common(&args);
+}
+
+static void test_postcopy_recovery_tls_psk(void)
+{
+ MigrateCommon args = {
+ .start_hook = test_migrate_tls_psk_start_match,
+ .finish_hook = test_migrate_tls_psk_finish,
+ };
+
+ test_postcopy_recovery_common(&args);
}
static void test_baddest(void)
@@ -2163,6 +2178,12 @@ int main(int argc, char **argv)
qtest_add_func("/migration/postcopy/tls/psk", test_postcopy_tls_psk);
#endif /* CONFIG_GNUTLS */
qtest_add_func("/migration/postcopy/recovery", test_postcopy_recovery);
+ qtest_add_func("/migration/postcopy/recovery/plain",
+ test_postcopy_recovery);
+#ifdef CONFIG_GNUTLS
+ qtest_add_func("/migration/postcopy/recovery/tls/psk",
+ test_postcopy_recovery_tls_psk);
+#endif /* CONFIG_GNUTLS */
}
qtest_add_func("/migration/bad_dest", test_baddest);
qtest_add_func("/migration/precopy/unix/plain", test_precopy_unix_plain);
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* [PATCH v9 14/14] tests: Add postcopy preempt tests
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (12 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 13/14] tests: Add postcopy tls recovery " Peter Xu
@ 2022-07-07 18:55 ` Peter Xu
2022-07-19 13:50 ` [PATCH v9 00/14] migration: Postcopy Preemption Dr. David Alan Gilbert
14 siblings, 0 replies; 22+ messages in thread
From: Peter Xu @ 2022-07-07 18:55 UTC (permalink / raw)
To: qemu-devel
Cc: Juan Quintela, peterx, Dr . David Alan Gilbert,
Leonardo Bras Soares Passos, Manish Mishra, Daniel P . Berrange
Four tests are added for preempt mode:
- Postcopy plain
- Postcopy recovery
- Postcopy tls
- Postcopy tls+recovery
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
tests/qtest/migration-test.c | 56 ++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)
diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index 81ef9741cd..81780189a8 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -569,6 +569,7 @@ typedef struct {
/* Postcopy specific fields */
void *postcopy_data;
+ bool postcopy_preempt;
} MigrateCommon;
static int test_migrate_start(QTestState **from, QTestState **to,
@@ -1074,6 +1075,11 @@ static int migrate_postcopy_prepare(QTestState **from_ptr,
migrate_set_capability(to, "postcopy-ram", true);
migrate_set_capability(to, "postcopy-blocktime", true);
+ if (args->postcopy_preempt) {
+ migrate_set_capability(from, "postcopy-preempt", true);
+ migrate_set_capability(to, "postcopy-preempt", true);
+ }
+
migrate_ensure_non_converge(from);
/* Wait for the first serial output from the source */
@@ -1137,6 +1143,26 @@ static void test_postcopy_tls_psk(void)
test_postcopy_common(&args);
}
+static void test_postcopy_preempt(void)
+{
+ MigrateCommon args = {
+ .postcopy_preempt = true,
+ };
+
+ test_postcopy_common(&args);
+}
+
+static void test_postcopy_preempt_tls_psk(void)
+{
+ MigrateCommon args = {
+ .postcopy_preempt = true,
+ .start_hook = test_migrate_tls_psk_start_match,
+ .finish_hook = test_migrate_tls_psk_finish,
+ };
+
+ test_postcopy_common(&args);
+}
+
static void test_postcopy_recovery_common(MigrateCommon *args)
{
QTestState *from, *to;
@@ -1216,6 +1242,27 @@ static void test_postcopy_recovery_tls_psk(void)
test_postcopy_recovery_common(&args);
}
+static void test_postcopy_preempt_recovery(void)
+{
+ MigrateCommon args = {
+ .postcopy_preempt = true,
+ };
+
+ test_postcopy_recovery_common(&args);
+}
+
+/* This contains preempt+recovery+tls test altogether */
+static void test_postcopy_preempt_all(void)
+{
+ MigrateCommon args = {
+ .postcopy_preempt = true,
+ .start_hook = test_migrate_tls_psk_start_match,
+ .finish_hook = test_migrate_tls_psk_finish,
+ };
+
+ test_postcopy_recovery_common(&args);
+}
+
static void test_baddest(void)
{
MigrateStart args = {
@@ -2183,6 +2230,15 @@ int main(int argc, char **argv)
#ifdef CONFIG_GNUTLS
qtest_add_func("/migration/postcopy/recovery/tls/psk",
test_postcopy_recovery_tls_psk);
+#endif /* CONFIG_GNUTLS */
+ qtest_add_func("/migration/postcopy/preempt/plain", test_postcopy_preempt);
+ qtest_add_func("/migration/postcopy/preempt/recovery/plain",
+ test_postcopy_preempt_recovery);
+#ifdef CONFIG_GNUTLS
+ qtest_add_func("/migration/postcopy/preempt/tls/psk",
+ test_postcopy_preempt_tls_psk);
+ qtest_add_func("/migration/postcopy/preempt/recovery/tls/psk",
+ test_postcopy_preempt_all);
#endif /* CONFIG_GNUTLS */
}
qtest_add_func("/migration/bad_dest", test_baddest);
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH v9 12/14] tests: Add postcopy tls migration test
2022-07-07 18:55 ` [PATCH v9 12/14] tests: Add postcopy tls migration test Peter Xu
@ 2022-07-13 11:25 ` Dr. David Alan Gilbert
0 siblings, 0 replies; 22+ messages in thread
From: Dr. David Alan Gilbert @ 2022-07-13 11:25 UTC (permalink / raw)
To: Peter Xu
Cc: qemu-devel, Juan Quintela, Leonardo Bras Soares Passos,
Manish Mishra, Daniel P . Berrange
* Peter Xu (peterx@redhat.com) wrote:
> We just added TLS tests for precopy but not postcopy. Add the
> corresponding test for vanilla postcopy.
>
> Rename the vanilla postcopy to "postcopy/plain" because all postcopy tests
> will only use unix sockets as channel.
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
> tests/qtest/migration-test.c | 61 ++++++++++++++++++++++++++++++------
> 1 file changed, 51 insertions(+), 10 deletions(-)
>
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index f15a7517b1..ee37ad6631 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -566,6 +566,9 @@ typedef struct {
>
> /* Optional: set number of migration passes to wait for */
> unsigned int iterations;
> +
> + /* Postcopy specific fields */
> + void *postcopy_data;
> } MigrateCommon;
>
> static int test_migrate_start(QTestState **from, QTestState **to,
> @@ -1054,15 +1057,19 @@ test_migrate_tls_x509_finish(QTestState *from,
>
> static int migrate_postcopy_prepare(QTestState **from_ptr,
> QTestState **to_ptr,
> - MigrateStart *args)
> + MigrateCommon *args)
> {
> g_autofree char *uri = g_strdup_printf("unix:%s/migsocket", tmpfs);
> QTestState *from, *to;
>
> - if (test_migrate_start(&from, &to, uri, args)) {
> + if (test_migrate_start(&from, &to, uri, &args->start)) {
> return -1;
> }
>
> + if (args->start_hook) {
> + args->postcopy_data = args->start_hook(from, to);
> + }
> +
> migrate_set_capability(from, "postcopy-ram", true);
> migrate_set_capability(to, "postcopy-ram", true);
> migrate_set_capability(to, "postcopy-blocktime", true);
> @@ -1082,7 +1089,8 @@ static int migrate_postcopy_prepare(QTestState **from_ptr,
> return 0;
> }
>
> -static void migrate_postcopy_complete(QTestState *from, QTestState *to)
> +static void migrate_postcopy_complete(QTestState *from, QTestState *to,
> + MigrateCommon *args)
> {
> wait_for_migration_complete(from);
>
> @@ -1093,25 +1101,48 @@ static void migrate_postcopy_complete(QTestState *from, QTestState *to)
> read_blocktime(to);
> }
>
> + if (args->finish_hook) {
> + args->finish_hook(from, to, args->postcopy_data);
> + args->postcopy_data = NULL;
> + }
> +
> test_migrate_end(from, to, true);
> }
>
> -static void test_postcopy(void)
> +static void test_postcopy_common(MigrateCommon *args)
> {
> - MigrateStart args = {};
> QTestState *from, *to;
>
> - if (migrate_postcopy_prepare(&from, &to, &args)) {
> + if (migrate_postcopy_prepare(&from, &to, args)) {
> return;
> }
> migrate_postcopy_start(from, to);
> - migrate_postcopy_complete(from, to);
> + migrate_postcopy_complete(from, to, args);
> +}
> +
> +static void test_postcopy(void)
> +{
> + MigrateCommon args = { };
> +
> + test_postcopy_common(&args);
> +}
> +
> +static void test_postcopy_tls_psk(void)
> +{
> + MigrateCommon args = {
> + .start_hook = test_migrate_tls_psk_start_match,
> + .finish_hook = test_migrate_tls_psk_finish,
> + };
> +
> + test_postcopy_common(&args);
> }
>
> static void test_postcopy_recovery(void)
> {
> - MigrateStart args = {
> - .hide_stderr = true,
> + MigrateCommon args = {
> + .start = {
> + .hide_stderr = true,
> + },
> };
> QTestState *from, *to;
> g_autofree char *uri = NULL;
> @@ -1167,7 +1198,7 @@ static void test_postcopy_recovery(void)
> /* Restore the postcopy bandwidth to unlimited */
> migrate_set_parameter_int(from, "max-postcopy-bandwidth", 0);
>
> - migrate_postcopy_complete(from, to);
> + migrate_postcopy_complete(from, to, &args);
> }
>
> static void test_baddest(void)
> @@ -2122,6 +2153,16 @@ int main(int argc, char **argv)
> if (has_uffd) {
> qtest_add_func("/migration/postcopy/unix", test_postcopy);
> qtest_add_func("/migration/postcopy/recovery", test_postcopy_recovery);
> + qtest_add_func("/migration/postcopy/plain", test_postcopy);
> +#ifdef CONFIG_GNUTLS
> + /*
> + * NOTE: psk test is enough for postcopy, as other types of TLS
> + * channels are tested under precopy. Here what we want to test is the
> + * general postcopy path that has TLS channel enabled.
> + */
> + qtest_add_func("/migration/postcopy/tls/psk", test_postcopy_tls_psk);
> +#endif /* CONFIG_GNUTLS */
> + qtest_add_func("/migration/postcopy/recovery", test_postcopy_recovery);
> }
> qtest_add_func("/migration/bad_dest", test_baddest);
> qtest_add_func("/migration/precopy/unix/plain", test_precopy_unix_plain);
> --
> 2.32.0
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v9 00/14] migration: Postcopy Preemption
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
` (13 preceding siblings ...)
2022-07-07 18:55 ` [PATCH v9 14/14] tests: Add postcopy preempt tests Peter Xu
@ 2022-07-19 13:50 ` Dr. David Alan Gilbert
14 siblings, 0 replies; 22+ messages in thread
From: Dr. David Alan Gilbert @ 2022-07-19 13:50 UTC (permalink / raw)
To: Peter Xu
Cc: qemu-devel, Leonardo Bras Soares Passos, Manish Mishra,
Juan Quintela, Daniel P . Berrange
* Peter Xu (peterx@redhat.com) wrote:
> Based on:
> [PATCH] tests: migration-test: Allow test to run without uffd
> https://lore.kernel.org/qemu-devel/20220707184600.24164-1-peterx@redhat.com/
>
> This is v8 of postcopy preempt series. It can also be found here:
> https://github.com/xzpeter/qemu/tree/postcopy-preempt
>
> RFC: https://lore.kernel.org/qemu-devel/20220119080929.39485-1-peterx@redhat.com
> V1: https://lore.kernel.org/qemu-devel/20220216062809.57179-1-peterx@redhat.com
> V2: https://lore.kernel.org/qemu-devel/20220301083925.33483-1-peterx@redhat.com
> V3: https://lore.kernel.org/qemu-devel/20220330213908.26608-1-peterx@redhat.com
> V4: https://lore.kernel.org/qemu-devel/20220331150857.74406-1-peterx@redhat.com
> V5: https://lore.kernel.org/qemu-devel/20220425233847.10393-1-peterx@redhat.com
> V6: https://lore.kernel.org/qemu-devel/20220517195730.32312-1-peterx@redhat.com
> V7: https://lore.kernel.org/qemu-devel/20220524221151.18225-1-peterx@redhat.com
> V8: https://lore.kernel.org/qemu-devel/20220622204920.79061-1-peterx@redhat.com
>
> v9:
> - Rebase upon latest master (plus the test fix above on "tests:
> migration-test: Allow test to run without uffd")
> - Added missing R-bs in v7
Queued, took some minor rework in the tests
> Abstract
> ========
>
> This series added a new migration capability called "postcopy-preempt". It can
> be enabled when postcopy is enabled, and it'll simply (but greatly) speed up
> postcopy page requests handling process.
>
> Below are some initial postcopy page request latency measurements after the
> new series applied.
>
> For each page size, I measured page request latency for three cases:
>
> (a) Vanilla: the old postcopy
> (b) Preempt no-break-huge: preempt enabled, x-postcopy-preempt-break-huge=off
> (c) Preempt full: preempt enabled, x-postcopy-preempt-break-huge=on
> (this is the default option when preempt enabled)
>
> Here x-postcopy-preempt-break-huge parameter is just added in v2 so as to
> conditionally disable the behavior to break sending a precopy huge page for
> debugging purpose. So when it's off, postcopy will not preempt precopy
> sending a huge page, but still postcopy will use its own channel.
>
> I tested it separately to give a rough idea on which part of the change
> helped how much of it. The overall benefit should be the comparison
> between case (a) and (c).
>
> |-----------+---------+-----------------------+--------------|
> | Page size | Vanilla | Preempt no-break-huge | Preempt full |
> |-----------+---------+-----------------------+--------------|
> | 4K | 10.68 | N/A [*] | 0.57 |
> | 2M | 10.58 | 5.49 | 5.02 |
> | 1G | 2046.65 | 933.185 | 649.445 |
> |-----------+---------+-----------------------+--------------|
> [*]: This case is N/A because 4K page does not contain huge page at all
>
> [1] https://github.com/xzpeter/small-stuffs/blob/master/tools/huge_vm/uffd-latency.bpf
>
> TODO List
> =========
>
> Avoid precopy write() blocks postcopy
> -------------------------------------
>
> I didn't prove this, but I always think the write() syscalls being blocked
> for precopy pages can affect postcopy services. If we can solve this
> problem then my wild guess is we can further reduce the average page
> latency.
>
> Two solutions at least in mind: (1) we could have made the write side of
> the migration channel NON_BLOCK too, or (2) multi-threads on send side,
> just like multifd, but we may use lock to protect which page to send too
> (e.g., the core idea is we should _never_ rely anything on the main thread,
> multifd has that dependency on queuing pages only on main thread).
>
> That can definitely be done and thought about later.
>
> Multi-channel for preemption threads
> ------------------------------------
>
> Currently the postcopy preempt feature use only one extra channel and one
> extra thread on dest (no new thread on src QEMU). It should be mostly good
> enough for major use cases, but when the postcopy queue is long enough
> (e.g. hundreds of vCPUs faulted on different pages) logically we could
> still observe more delays in average. Whether growing threads/channels can
> solve it is debatable, but sounds worthwhile a try. That's yet another
> thing we can think about after this patchset lands.
>
> Logically the design provides space for that - the receiving postcopy
> preempt thread can understand all ram-layer migration protocol, and for
> multi channel and multi threads we could simply grow that into multile
> threads handling the same protocol (with multiple PostcopyTmpPage). The
> source needs more thoughts on synchronizations, though, but it shouldn't
> affect the whole protocol layer, so should be easy to keep compatible.
>
> Please review, thanks.
>
> Peter Xu (14):
> migration: Add postcopy-preempt capability
> migration: Postcopy preemption preparation on channel creation
> migration: Postcopy preemption enablement
> migration: Postcopy recover with preempt enabled
> migration: Create the postcopy preempt channel asynchronously
> migration: Add property x-postcopy-preempt-break-huge
> migration: Add helpers to detect TLS capability
> migration: Export tls-[creds|hostname|authz] params to cmdline too
> migration: Enable TLS for preempt channel
> migration: Respect postcopy request order in preemption mode
> tests: Move MigrateCommon upper
> tests: Add postcopy tls migration test
> tests: Add postcopy tls recovery migration test
> tests: Add postcopy preempt tests
>
> migration/channel.c | 9 +-
> migration/migration.c | 134 ++++++++++++--
> migration/migration.h | 44 ++++-
> migration/multifd.c | 4 +-
> migration/postcopy-ram.c | 186 +++++++++++++++++++-
> migration/postcopy-ram.h | 11 ++
> migration/qemu-file.c | 27 +++
> migration/qemu-file.h | 1 +
> migration/ram.c | 326 +++++++++++++++++++++++++++++++++--
> migration/ram.h | 4 +-
> migration/savevm.c | 46 +++--
> migration/socket.c | 22 ++-
> migration/socket.h | 1 +
> migration/tls.c | 9 +
> migration/tls.h | 4 +
> migration/trace-events | 15 +-
> qapi/migration.json | 7 +-
> tests/qtest/migration-test.c | 286 +++++++++++++++++++++---------
> 18 files changed, 990 insertions(+), 146 deletions(-)
>
> --
> 2.32.0
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation
2022-07-07 18:55 ` [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation Peter Xu
@ 2022-07-19 15:15 ` Dr. David Alan Gilbert
2022-07-19 15:25 ` Peter Xu
0 siblings, 1 reply; 22+ messages in thread
From: Dr. David Alan Gilbert @ 2022-07-19 15:15 UTC (permalink / raw)
To: Peter Xu
Cc: qemu-devel, Juan Quintela, Leonardo Bras Soares Passos,
Manish Mishra, Daniel P . Berrange
* Peter Xu (peterx@redhat.com) wrote:
> Create a new socket for postcopy to be prepared to send postcopy requested
> pages via this specific channel, so as to not get blocked by precopy pages.
>
> A new thread is also created on dest qemu to receive data from this new channel
> based on the ram_load_postcopy() routine.
>
> The ram_load_postcopy(POSTCOPY) branch and the thread has not started to
> function, and that'll be done in follow up patches.
>
> Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new
> thread too to make sure it'll be recycled properly.
I'm hitting a CI failure here:
https://gitlab.com/dagrh/qemu/-/jobs/2741659845
c.o -c ../migration/migration.c
../migration/migration.c: In function ‘migration_ioc_process_incoming’:
../migration/migration.c:766:8: error: ‘start_migration’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
766 | if (start_migration) {
| ^
> Reviewed-by: Daniel P. Berrang?? <berrange@redhat.com>
> Reviewed-by: Juan Quintela <quintela@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> migration/migration.c | 62 +++++++++++++++++++++++----
> migration/migration.h | 8 ++++
> migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++--
> migration/postcopy-ram.h | 10 +++++
> migration/ram.c | 25 ++++++++---
> migration/ram.h | 4 +-
> migration/savevm.c | 20 ++++-----
> migration/socket.c | 22 +++++++++-
> migration/socket.h | 1 +
> migration/trace-events | 5 ++-
> 10 files changed, 218 insertions(+), 31 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index ce7bb68cdc..9484fec0b2 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void)
> mis->page_requested = NULL;
> }
>
> + if (mis->postcopy_qemufile_dst) {
> + migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
> + qemu_fclose(mis->postcopy_qemufile_dst);
> + mis->postcopy_qemufile_dst = NULL;
> + }
> +
> yank_unregister_instance(MIGRATION_YANK_INSTANCE);
> }
>
> @@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error **errp)
> migration_incoming_process();
> }
>
> +static bool migration_needs_multiple_sockets(void)
> +{
> + return migrate_use_multifd() || migrate_postcopy_preempt();
> +}
> +
> void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> {
> MigrationIncomingState *mis = migration_incoming_get_current();
> Error *local_err = NULL;
> bool start_migration;
> + QEMUFile *f;
>
> if (!mis->from_src_file) {
> /* The first connection (multifd may have multiple) */
> - QEMUFile *f = qemu_file_new_input(ioc);
> + f = qemu_file_new_input(ioc);
>
> if (!migration_incoming_setup(f, errp)) {
> return;
> @@ -730,13 +742,18 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
>
> /*
> * Common migration only needs one channel, so we can start
> - * right now. Multifd needs more than one channel, we wait.
> + * right now. Some features need more than one channel, we wait.
> */
> - start_migration = !migrate_use_multifd();
> + start_migration = !migration_needs_multiple_sockets();
> } else {
> /* Multiple connections */
> - assert(migrate_use_multifd());
> - start_migration = multifd_recv_new_channel(ioc, &local_err);
> + assert(migration_needs_multiple_sockets());
> + if (migrate_use_multifd()) {
> + start_migration = multifd_recv_new_channel(ioc, &local_err);
> + } else if (migrate_postcopy_preempt()) {
> + f = qemu_file_new_input(ioc);
> + start_migration = postcopy_preempt_new_channel(mis, f);
> + }
So that doesn't always set start_migration?
Dave
> if (local_err) {
> error_propagate(errp, local_err);
> return;
> @@ -761,11 +778,20 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> bool migration_has_all_channels(void)
> {
> MigrationIncomingState *mis = migration_incoming_get_current();
> - bool all_channels;
>
> - all_channels = multifd_recv_all_channels_created();
> + if (!mis->from_src_file) {
> + return false;
> + }
> +
> + if (migrate_use_multifd()) {
> + return multifd_recv_all_channels_created();
> + }
> +
> + if (migrate_postcopy_preempt()) {
> + return mis->postcopy_qemufile_dst != NULL;
> + }
>
> - return all_channels && mis->from_src_file != NULL;
> + return true;
> }
>
> /*
> @@ -1874,6 +1900,12 @@ static void migrate_fd_cleanup(MigrationState *s)
> qemu_fclose(tmp);
> }
>
> + if (s->postcopy_qemufile_src) {
> + migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src);
> + qemu_fclose(s->postcopy_qemufile_src);
> + s->postcopy_qemufile_src = NULL;
> + }
> +
> assert(!migration_is_active(s));
>
> if (s->state == MIGRATION_STATUS_CANCELLING) {
> @@ -3269,6 +3301,11 @@ static void migration_completion(MigrationState *s)
> qemu_savevm_state_complete_postcopy(s->to_dst_file);
> qemu_mutex_unlock_iothread();
>
> + /* Shutdown the postcopy fast path thread */
> + if (migrate_postcopy_preempt()) {
> + postcopy_preempt_shutdown_file(s);
> + }
> +
> trace_migration_completion_postcopy_end_after_complete();
> } else {
> goto fail;
> @@ -4157,6 +4194,15 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
> }
> }
>
> + /* This needs to be done before resuming a postcopy */
> + if (postcopy_preempt_setup(s, &local_err)) {
> + error_report_err(local_err);
> + migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
> + MIGRATION_STATUS_FAILED);
> + migrate_fd_cleanup(s);
> + return;
> + }
> +
> if (resume) {
> /* Wakeup the main migration thread to do the recovery */
> migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
> diff --git a/migration/migration.h b/migration/migration.h
> index d2269c826c..941c61e543 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -23,6 +23,7 @@
> #include "io/channel-buffer.h"
> #include "net/announce.h"
> #include "qom/object.h"
> +#include "postcopy-ram.h"
>
> struct PostcopyBlocktimeContext;
>
> @@ -112,6 +113,11 @@ struct MigrationIncomingState {
> * enabled.
> */
> unsigned int postcopy_channels;
> + /* QEMUFile for postcopy only; it'll be handled by a separate thread */
> + QEMUFile *postcopy_qemufile_dst;
> + /* Postcopy priority thread is used to receive postcopy requested pages */
> + QemuThread postcopy_prio_thread;
> + bool postcopy_prio_thread_created;
> /*
> * An array of temp host huge pages to be used, one for each postcopy
> * channel.
> @@ -192,6 +198,8 @@ struct MigrationState {
> QEMUBH *cleanup_bh;
> /* Protected by qemu_file_lock */
> QEMUFile *to_dst_file;
> + /* Postcopy specific transfer channel */
> + QEMUFile *postcopy_qemufile_src;
> QIOChannelBuffer *bioc;
> /*
> * Protects to_dst_file/from_dst_file pointers. We need to make sure we
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index a66dd536d9..a3561410fe 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -33,6 +33,9 @@
> #include "trace.h"
> #include "hw/boards.h"
> #include "exec/ramblock.h"
> +#include "socket.h"
> +#include "qemu-file.h"
> +#include "yank_functions.h"
>
> /* Arbitrary limit on size of each discard command,
> * keeps them around ~200 bytes
> @@ -567,6 +570,11 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
> {
> trace_postcopy_ram_incoming_cleanup_entry();
>
> + if (mis->postcopy_prio_thread_created) {
> + qemu_thread_join(&mis->postcopy_prio_thread);
> + mis->postcopy_prio_thread_created = false;
> + }
> +
> if (mis->have_fault_thread) {
> Error *local_err = NULL;
>
> @@ -1102,8 +1110,13 @@ static int postcopy_temp_pages_setup(MigrationIncomingState *mis)
> int err, i, channels;
> void *temp_page;
>
> - /* TODO: will be boosted when enable postcopy preemption */
> - mis->postcopy_channels = 1;
> + if (migrate_postcopy_preempt()) {
> + /* If preemption enabled, need extra channel for urgent requests */
> + mis->postcopy_channels = RAM_CHANNEL_MAX;
> + } else {
> + /* Both precopy/postcopy on the same channel */
> + mis->postcopy_channels = 1;
> + }
>
> channels = mis->postcopy_channels;
> mis->postcopy_tmp_pages = g_malloc0_n(sizeof(PostcopyTmpPage), channels);
> @@ -1170,7 +1183,7 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
> return -1;
> }
>
> - postcopy_thread_create(mis, &mis->fault_thread, "postcopy/fault",
> + postcopy_thread_create(mis, &mis->fault_thread, "fault-default",
> postcopy_ram_fault_thread, QEMU_THREAD_JOINABLE);
> mis->have_fault_thread = true;
>
> @@ -1185,6 +1198,16 @@ int postcopy_ram_incoming_setup(MigrationIncomingState *mis)
> return -1;
> }
>
> + if (migrate_postcopy_preempt()) {
> + /*
> + * This thread needs to be created after the temp pages because
> + * it'll fetch RAM_CHANNEL_POSTCOPY PostcopyTmpPage immediately.
> + */
> + postcopy_thread_create(mis, &mis->postcopy_prio_thread, "fault-fast",
> + postcopy_preempt_thread, QEMU_THREAD_JOINABLE);
> + mis->postcopy_prio_thread_created = true;
> + }
> +
> trace_postcopy_ram_enable_notify();
>
> return 0;
> @@ -1514,3 +1537,66 @@ void postcopy_unregister_shared_ufd(struct PostCopyFD *pcfd)
> }
> }
> }
> +
> +bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
> +{
> + /*
> + * The new loading channel has its own threads, so it needs to be
> + * blocked too. It's by default true, just be explicit.
> + */
> + qemu_file_set_blocking(file, true);
> + mis->postcopy_qemufile_dst = file;
> + trace_postcopy_preempt_new_channel();
> +
> + /* Start the migration immediately */
> + return true;
> +}
> +
> +int postcopy_preempt_setup(MigrationState *s, Error **errp)
> +{
> + QIOChannel *ioc;
> +
> + if (!migrate_postcopy_preempt()) {
> + return 0;
> + }
> +
> + if (!migrate_multi_channels_is_allowed()) {
> + error_setg(errp, "Postcopy preempt is not supported as current "
> + "migration stream does not support multi-channels.");
> + return -1;
> + }
> +
> + ioc = socket_send_channel_create_sync(errp);
> +
> + if (ioc == NULL) {
> + return -1;
> + }
> +
> + migration_ioc_register_yank(ioc);
> + s->postcopy_qemufile_src = qemu_file_new_output(ioc);
> +
> + trace_postcopy_preempt_new_channel();
> +
> + return 0;
> +}
> +
> +void *postcopy_preempt_thread(void *opaque)
> +{
> + MigrationIncomingState *mis = opaque;
> + int ret;
> +
> + trace_postcopy_preempt_thread_entry();
> +
> + rcu_register_thread();
> +
> + qemu_sem_post(&mis->thread_sync_sem);
> +
> + /* Sending RAM_SAVE_FLAG_EOS to terminate this thread */
> + ret = ram_load_postcopy(mis->postcopy_qemufile_dst, RAM_CHANNEL_POSTCOPY);
> +
> + rcu_unregister_thread();
> +
> + trace_postcopy_preempt_thread_exit();
> +
> + return ret == 0 ? NULL : (void *)-1;
> +}
> diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
> index 07684c0e1d..34b1080cde 100644
> --- a/migration/postcopy-ram.h
> +++ b/migration/postcopy-ram.h
> @@ -183,4 +183,14 @@ int postcopy_wake_shared(struct PostCopyFD *pcfd, uint64_t client_addr,
> int postcopy_request_shared_page(struct PostCopyFD *pcfd, RAMBlock *rb,
> uint64_t client_addr, uint64_t offset);
>
> +/* Hard-code channels for now for postcopy preemption */
> +enum PostcopyChannels {
> + RAM_CHANNEL_PRECOPY = 0,
> + RAM_CHANNEL_POSTCOPY = 1,
> + RAM_CHANNEL_MAX,
> +};
> +
> +bool postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file);
> +int postcopy_preempt_setup(MigrationState *s, Error **errp);
> +
> #endif
> diff --git a/migration/ram.c b/migration/ram.c
> index 01f9cc1d72..e4364c0bff 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -3659,15 +3659,15 @@ int ram_postcopy_incoming_init(MigrationIncomingState *mis)
> * rcu_read_lock is taken prior to this being called.
> *
> * @f: QEMUFile where to send the data
> + * @channel: the channel to use for loading
> */
> -int ram_load_postcopy(QEMUFile *f)
> +int ram_load_postcopy(QEMUFile *f, int channel)
> {
> int flags = 0, ret = 0;
> bool place_needed = false;
> bool matches_target_page_size = false;
> MigrationIncomingState *mis = migration_incoming_get_current();
> - /* Currently we only use channel 0. TODO: use all the channels */
> - PostcopyTmpPage *tmp_page = &mis->postcopy_tmp_pages[0];
> + PostcopyTmpPage *tmp_page = &mis->postcopy_tmp_pages[channel];
>
> while (!ret && !(flags & RAM_SAVE_FLAG_EOS)) {
> ram_addr_t addr;
> @@ -3691,7 +3691,7 @@ int ram_load_postcopy(QEMUFile *f)
> flags = addr & ~TARGET_PAGE_MASK;
> addr &= TARGET_PAGE_MASK;
>
> - trace_ram_load_postcopy_loop((uint64_t)addr, flags);
> + trace_ram_load_postcopy_loop(channel, (uint64_t)addr, flags);
> if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
> RAM_SAVE_FLAG_COMPRESS_PAGE)) {
> block = ram_block_from_stream(mis, f, flags);
> @@ -3732,10 +3732,10 @@ int ram_load_postcopy(QEMUFile *f)
> } else if (tmp_page->host_addr !=
> host_page_from_ram_block_offset(block, addr)) {
> /* not the 1st TP within the HP */
> - error_report("Non-same host page detected. "
> + error_report("Non-same host page detected on channel %d: "
> "Target host page %p, received host page %p "
> "(rb %s offset 0x"RAM_ADDR_FMT" target_pages %d)",
> - tmp_page->host_addr,
> + channel, tmp_page->host_addr,
> host_page_from_ram_block_offset(block, addr),
> block->idstr, addr, tmp_page->target_pages);
> ret = -EINVAL;
> @@ -4122,7 +4122,12 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
> */
> WITH_RCU_READ_LOCK_GUARD() {
> if (postcopy_running) {
> - ret = ram_load_postcopy(f);
> + /*
> + * Note! Here RAM_CHANNEL_PRECOPY is the precopy channel of
> + * postcopy migration, we have another RAM_CHANNEL_POSTCOPY to
> + * service fast page faults.
> + */
> + ret = ram_load_postcopy(f, RAM_CHANNEL_PRECOPY);
> } else {
> ret = ram_load_precopy(f);
> }
> @@ -4284,6 +4289,12 @@ static int ram_resume_prepare(MigrationState *s, void *opaque)
> return 0;
> }
>
> +void postcopy_preempt_shutdown_file(MigrationState *s)
> +{
> + qemu_put_be64(s->postcopy_qemufile_src, RAM_SAVE_FLAG_EOS);
> + qemu_fflush(s->postcopy_qemufile_src);
> +}
> +
> static SaveVMHandlers savevm_ram_handlers = {
> .save_setup = ram_save_setup,
> .save_live_iterate = ram_save_iterate,
> diff --git a/migration/ram.h b/migration/ram.h
> index ded0a3a086..5d90945a6e 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -61,7 +61,7 @@ void ram_postcopy_send_discard_bitmap(MigrationState *ms);
> /* For incoming postcopy discard */
> int ram_discard_range(const char *block_name, uint64_t start, size_t length);
> int ram_postcopy_incoming_init(MigrationIncomingState *mis);
> -int ram_load_postcopy(QEMUFile *f);
> +int ram_load_postcopy(QEMUFile *f, int channel);
>
> void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
>
> @@ -73,6 +73,8 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file,
> const char *block_name);
> int ram_dirty_bitmap_reload(MigrationState *s, RAMBlock *rb);
> bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t start);
> +void postcopy_preempt_shutdown_file(MigrationState *s);
> +void *postcopy_preempt_thread(void *opaque);
>
> /* ram cache */
> int colo_init_ram_cache(void);
> diff --git a/migration/savevm.c b/migration/savevm.c
> index e8a1b96fcd..e3af03cb9b 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2540,16 +2540,6 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
> {
> int i;
>
> - /*
> - * If network is interrupted, any temp page we received will be useless
> - * because we didn't mark them as "received" in receivedmap. After a
> - * proper recovery later (which will sync src dirty bitmap with receivedmap
> - * on dest) these cached small pages will be resent again.
> - */
> - for (i = 0; i < mis->postcopy_channels; i++) {
> - postcopy_temp_page_reset(&mis->postcopy_tmp_pages[i]);
> - }
> -
> trace_postcopy_pause_incoming();
>
> assert(migrate_postcopy_ram());
> @@ -2578,6 +2568,16 @@ static bool postcopy_pause_incoming(MigrationIncomingState *mis)
> /* Notify the fault thread for the invalidated file handle */
> postcopy_fault_thread_notify(mis);
>
> + /*
> + * If network is interrupted, any temp page we received will be useless
> + * because we didn't mark them as "received" in receivedmap. After a
> + * proper recovery later (which will sync src dirty bitmap with receivedmap
> + * on dest) these cached small pages will be resent again.
> + */
> + for (i = 0; i < mis->postcopy_channels; i++) {
> + postcopy_temp_page_reset(&mis->postcopy_tmp_pages[i]);
> + }
> +
> error_report("Detected IO failure for postcopy. "
> "Migration paused.");
>
> diff --git a/migration/socket.c b/migration/socket.c
> index 4fd5e85f50..e6fdf3c5e1 100644
> --- a/migration/socket.c
> +++ b/migration/socket.c
> @@ -26,7 +26,7 @@
> #include "io/channel-socket.h"
> #include "io/net-listener.h"
> #include "trace.h"
> -
> +#include "postcopy-ram.h"
>
> struct SocketOutgoingArgs {
> SocketAddress *saddr;
> @@ -39,6 +39,24 @@ void socket_send_channel_create(QIOTaskFunc f, void *data)
> f, data, NULL, NULL);
> }
>
> +QIOChannel *socket_send_channel_create_sync(Error **errp)
> +{
> + QIOChannelSocket *sioc = qio_channel_socket_new();
> +
> + if (!outgoing_args.saddr) {
> + object_unref(OBJECT(sioc));
> + error_setg(errp, "Initial sock address not set!");
> + return NULL;
> + }
> +
> + if (qio_channel_socket_connect_sync(sioc, outgoing_args.saddr, errp) < 0) {
> + object_unref(OBJECT(sioc));
> + return NULL;
> + }
> +
> + return QIO_CHANNEL(sioc);
> +}
> +
> int socket_send_channel_destroy(QIOChannel *send)
> {
> /* Remove channel */
> @@ -166,6 +184,8 @@ socket_start_incoming_migration_internal(SocketAddress *saddr,
>
> if (migrate_use_multifd()) {
> num = migrate_multifd_channels();
> + } else if (migrate_postcopy_preempt()) {
> + num = RAM_CHANNEL_MAX;
> }
>
> if (qio_net_listener_open_sync(listener, saddr, num, errp) < 0) {
> diff --git a/migration/socket.h b/migration/socket.h
> index 891dbccceb..dc54df4e6c 100644
> --- a/migration/socket.h
> +++ b/migration/socket.h
> @@ -21,6 +21,7 @@
> #include "io/task.h"
>
> void socket_send_channel_create(QIOTaskFunc f, void *data);
> +QIOChannel *socket_send_channel_create_sync(Error **errp);
> int socket_send_channel_destroy(QIOChannel *send);
>
> void socket_start_incoming_migration(const char *str, Error **errp);
> diff --git a/migration/trace-events b/migration/trace-events
> index 1aec580e92..4bc787cf0c 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -91,7 +91,7 @@ migration_bitmap_clear_dirty(char *str, uint64_t start, uint64_t size, unsigned
> migration_throttle(void) ""
> ram_discard_range(const char *rbname, uint64_t start, size_t len) "%s: start: %" PRIx64 " %zx"
> ram_load_loop(const char *rbname, uint64_t addr, int flags, void *host) "%s: addr: 0x%" PRIx64 " flags: 0x%x host: %p"
> -ram_load_postcopy_loop(uint64_t addr, int flags) "@%" PRIx64 " %x"
> +ram_load_postcopy_loop(int channel, uint64_t addr, int flags) "chan=%d addr=0x%" PRIx64 " flags=0x%x"
> ram_postcopy_send_discard_bitmap(void) ""
> ram_save_page(const char *rbname, uint64_t offset, void *host) "%s: offset: 0x%" PRIx64 " host: %p"
> ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s: start: 0x%zx len: 0x%zx"
> @@ -278,6 +278,9 @@ postcopy_request_shared_page(const char *sharer, const char *rb, uint64_t rb_off
> postcopy_request_shared_page_present(const char *sharer, const char *rb, uint64_t rb_offset) "%s already %s offset 0x%"PRIx64
> postcopy_wake_shared(uint64_t client_addr, const char *rb) "at 0x%"PRIx64" in %s"
> postcopy_page_req_del(void *addr, int count) "resolved page req %p total %d"
> +postcopy_preempt_new_channel(void) ""
> +postcopy_preempt_thread_entry(void) ""
> +postcopy_preempt_thread_exit(void) ""
>
> get_mem_fault_cpu_index(int cpu, uint32_t pid) "cpu: %d, pid: %u"
>
> --
> 2.32.0
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation
2022-07-19 15:15 ` Dr. David Alan Gilbert
@ 2022-07-19 15:25 ` Peter Xu
2022-07-19 15:31 ` Dr. David Alan Gilbert
0 siblings, 1 reply; 22+ messages in thread
From: Peter Xu @ 2022-07-19 15:25 UTC (permalink / raw)
To: Dr. David Alan Gilbert
Cc: qemu-devel, Juan Quintela, Leonardo Bras Soares Passos,
Manish Mishra, Daniel P . Berrange
On Tue, Jul 19, 2022 at 04:15:49PM +0100, Dr. David Alan Gilbert wrote:
> * Peter Xu (peterx@redhat.com) wrote:
> > Create a new socket for postcopy to be prepared to send postcopy requested
> > pages via this specific channel, so as to not get blocked by precopy pages.
> >
> > A new thread is also created on dest qemu to receive data from this new channel
> > based on the ram_load_postcopy() routine.
> >
> > The ram_load_postcopy(POSTCOPY) branch and the thread has not started to
> > function, and that'll be done in follow up patches.
> >
> > Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new
> > thread too to make sure it'll be recycled properly.
>
> I'm hitting a CI failure here:
> https://gitlab.com/dagrh/qemu/-/jobs/2741659845
>
> c.o -c ../migration/migration.c
> ../migration/migration.c: In function ‘migration_ioc_process_incoming’:
> ../migration/migration.c:766:8: error: ‘start_migration’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 766 | if (start_migration) {
> | ^
>
> > Reviewed-by: Daniel P. Berrang?? <berrange@redhat.com>
> > Reviewed-by: Juan Quintela <quintela@redhat.com>
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> > ---
> > migration/migration.c | 62 +++++++++++++++++++++++----
> > migration/migration.h | 8 ++++
> > migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++--
> > migration/postcopy-ram.h | 10 +++++
> > migration/ram.c | 25 ++++++++---
> > migration/ram.h | 4 +-
> > migration/savevm.c | 20 ++++-----
> > migration/socket.c | 22 +++++++++-
> > migration/socket.h | 1 +
> > migration/trace-events | 5 ++-
> > 10 files changed, 218 insertions(+), 31 deletions(-)
> >
> > diff --git a/migration/migration.c b/migration/migration.c
> > index ce7bb68cdc..9484fec0b2 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void)
> > mis->page_requested = NULL;
> > }
> >
> > + if (mis->postcopy_qemufile_dst) {
> > + migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
> > + qemu_fclose(mis->postcopy_qemufile_dst);
> > + mis->postcopy_qemufile_dst = NULL;
> > + }
> > +
> > yank_unregister_instance(MIGRATION_YANK_INSTANCE);
> > }
> >
> > @@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error **errp)
> > migration_incoming_process();
> > }
> >
> > +static bool migration_needs_multiple_sockets(void)
> > +{
> > + return migrate_use_multifd() || migrate_postcopy_preempt();
> > +}
> > +
> > void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > {
> > MigrationIncomingState *mis = migration_incoming_get_current();
> > Error *local_err = NULL;
> > bool start_migration;
> > + QEMUFile *f;
> >
> > if (!mis->from_src_file) {
> > /* The first connection (multifd may have multiple) */
> > - QEMUFile *f = qemu_file_new_input(ioc);
> > + f = qemu_file_new_input(ioc);
> >
> > if (!migration_incoming_setup(f, errp)) {
> > return;
> > @@ -730,13 +742,18 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> >
> > /*
> > * Common migration only needs one channel, so we can start
> > - * right now. Multifd needs more than one channel, we wait.
> > + * right now. Some features need more than one channel, we wait.
> > */
> > - start_migration = !migrate_use_multifd();
> > + start_migration = !migration_needs_multiple_sockets();
> > } else {
> > /* Multiple connections */
> > - assert(migrate_use_multifd());
> > - start_migration = multifd_recv_new_channel(ioc, &local_err);
> > + assert(migration_needs_multiple_sockets());
> > + if (migrate_use_multifd()) {
> > + start_migration = multifd_recv_new_channel(ioc, &local_err);
> > + } else if (migrate_postcopy_preempt()) {
> > + f = qemu_file_new_input(ioc);
> > + start_migration = postcopy_preempt_new_channel(mis, f);
> > + }
>
> So that doesn't always set start_migration?
Logically it should, because we asserted on
migration_needs_multiple_sockets(), while multifd and preempt mode are the
only two that may need multiple sockets. So it must go into either of
them.
A fix could be like this:
diff --git a/migration/migration.c b/migration/migration.c
index 76cf2a72c0..7c7e529ca7 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -753,7 +753,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
assert(migration_needs_multiple_sockets());
if (migrate_use_multifd()) {
start_migration = multifd_recv_new_channel(ioc, &local_err);
- } else if (migrate_postcopy_preempt()) {
+ } else {
+ assert(migrate_postcopy_preempt());
f = qemu_file_new_input(ioc);
start_migration = postcopy_preempt_new_channel(mis, f);
}
Or we simply set start_migration=false as initial value.
Should I repost the series?
Thanks,
--
Peter Xu
^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation
2022-07-19 15:25 ` Peter Xu
@ 2022-07-19 15:31 ` Dr. David Alan Gilbert
2022-07-19 15:39 ` Peter Xu
0 siblings, 1 reply; 22+ messages in thread
From: Dr. David Alan Gilbert @ 2022-07-19 15:31 UTC (permalink / raw)
To: Peter Xu
Cc: qemu-devel, Juan Quintela, Leonardo Bras Soares Passos,
Manish Mishra, Daniel P . Berrange
* Peter Xu (peterx@redhat.com) wrote:
> On Tue, Jul 19, 2022 at 04:15:49PM +0100, Dr. David Alan Gilbert wrote:
> > * Peter Xu (peterx@redhat.com) wrote:
> > > Create a new socket for postcopy to be prepared to send postcopy requested
> > > pages via this specific channel, so as to not get blocked by precopy pages.
> > >
> > > A new thread is also created on dest qemu to receive data from this new channel
> > > based on the ram_load_postcopy() routine.
> > >
> > > The ram_load_postcopy(POSTCOPY) branch and the thread has not started to
> > > function, and that'll be done in follow up patches.
> > >
> > > Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new
> > > thread too to make sure it'll be recycled properly.
> >
> > I'm hitting a CI failure here:
> > https://gitlab.com/dagrh/qemu/-/jobs/2741659845
> >
> > c.o -c ../migration/migration.c
> > ../migration/migration.c: In function ‘migration_ioc_process_incoming’:
> > ../migration/migration.c:766:8: error: ‘start_migration’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > 766 | if (start_migration) {
> > | ^
> >
> > > Reviewed-by: Daniel P. Berrang?? <berrange@redhat.com>
> > > Reviewed-by: Juan Quintela <quintela@redhat.com>
> > > Signed-off-by: Peter Xu <peterx@redhat.com>
> > > ---
> > > migration/migration.c | 62 +++++++++++++++++++++++----
> > > migration/migration.h | 8 ++++
> > > migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++--
> > > migration/postcopy-ram.h | 10 +++++
> > > migration/ram.c | 25 ++++++++---
> > > migration/ram.h | 4 +-
> > > migration/savevm.c | 20 ++++-----
> > > migration/socket.c | 22 +++++++++-
> > > migration/socket.h | 1 +
> > > migration/trace-events | 5 ++-
> > > 10 files changed, 218 insertions(+), 31 deletions(-)
> > >
> > > diff --git a/migration/migration.c b/migration/migration.c
> > > index ce7bb68cdc..9484fec0b2 100644
> > > --- a/migration/migration.c
> > > +++ b/migration/migration.c
> > > @@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void)
> > > mis->page_requested = NULL;
> > > }
> > >
> > > + if (mis->postcopy_qemufile_dst) {
> > > + migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
> > > + qemu_fclose(mis->postcopy_qemufile_dst);
> > > + mis->postcopy_qemufile_dst = NULL;
> > > + }
> > > +
> > > yank_unregister_instance(MIGRATION_YANK_INSTANCE);
> > > }
> > >
> > > @@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error **errp)
> > > migration_incoming_process();
> > > }
> > >
> > > +static bool migration_needs_multiple_sockets(void)
> > > +{
> > > + return migrate_use_multifd() || migrate_postcopy_preempt();
> > > +}
> > > +
> > > void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > > {
> > > MigrationIncomingState *mis = migration_incoming_get_current();
> > > Error *local_err = NULL;
> > > bool start_migration;
> > > + QEMUFile *f;
> > >
> > > if (!mis->from_src_file) {
> > > /* The first connection (multifd may have multiple) */
> > > - QEMUFile *f = qemu_file_new_input(ioc);
> > > + f = qemu_file_new_input(ioc);
> > >
> > > if (!migration_incoming_setup(f, errp)) {
> > > return;
> > > @@ -730,13 +742,18 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > >
> > > /*
> > > * Common migration only needs one channel, so we can start
> > > - * right now. Multifd needs more than one channel, we wait.
> > > + * right now. Some features need more than one channel, we wait.
> > > */
> > > - start_migration = !migrate_use_multifd();
> > > + start_migration = !migration_needs_multiple_sockets();
> > > } else {
> > > /* Multiple connections */
> > > - assert(migrate_use_multifd());
> > > - start_migration = multifd_recv_new_channel(ioc, &local_err);
> > > + assert(migration_needs_multiple_sockets());
> > > + if (migrate_use_multifd()) {
> > > + start_migration = multifd_recv_new_channel(ioc, &local_err);
> > > + } else if (migrate_postcopy_preempt()) {
> > > + f = qemu_file_new_input(ioc);
> > > + start_migration = postcopy_preempt_new_channel(mis, f);
> > > + }
> >
> > So that doesn't always set start_migration?
>
> Logically it should, because we asserted on
> migration_needs_multiple_sockets(), while multifd and preempt mode are the
> only two that may need multiple sockets. So it must go into either of
> them.
>
> A fix could be like this:
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 76cf2a72c0..7c7e529ca7 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -753,7 +753,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> assert(migration_needs_multiple_sockets());
> if (migrate_use_multifd()) {
> start_migration = multifd_recv_new_channel(ioc, &local_err);
> - } else if (migrate_postcopy_preempt()) {
> + } else {
> + assert(migrate_postcopy_preempt());
> f = qemu_file_new_input(ioc);
> start_migration = postcopy_preempt_new_channel(mis, f);
> }
>
> Or we simply set start_migration=false as initial value.
>
> Should I repost the series?
No just post a fixup and I'll merge it.
Dave
> Thanks,
>
> --
> Peter Xu
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation
2022-07-19 15:31 ` Dr. David Alan Gilbert
@ 2022-07-19 15:39 ` Peter Xu
2022-07-19 16:06 ` Dr. David Alan Gilbert
0 siblings, 1 reply; 22+ messages in thread
From: Peter Xu @ 2022-07-19 15:39 UTC (permalink / raw)
To: Dr. David Alan Gilbert
Cc: qemu-devel, Juan Quintela, Leonardo Bras Soares Passos,
Manish Mishra, Daniel P . Berrange
[-- Attachment #1: Type: text/plain, Size: 5936 bytes --]
On Tue, Jul 19, 2022 at 04:31:20PM +0100, Dr. David Alan Gilbert wrote:
> * Peter Xu (peterx@redhat.com) wrote:
> > On Tue, Jul 19, 2022 at 04:15:49PM +0100, Dr. David Alan Gilbert wrote:
> > > * Peter Xu (peterx@redhat.com) wrote:
> > > > Create a new socket for postcopy to be prepared to send postcopy requested
> > > > pages via this specific channel, so as to not get blocked by precopy pages.
> > > >
> > > > A new thread is also created on dest qemu to receive data from this new channel
> > > > based on the ram_load_postcopy() routine.
> > > >
> > > > The ram_load_postcopy(POSTCOPY) branch and the thread has not started to
> > > > function, and that'll be done in follow up patches.
> > > >
> > > > Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new
> > > > thread too to make sure it'll be recycled properly.
> > >
> > > I'm hitting a CI failure here:
> > > https://gitlab.com/dagrh/qemu/-/jobs/2741659845
> > >
> > > c.o -c ../migration/migration.c
> > > ../migration/migration.c: In function ‘migration_ioc_process_incoming’:
> > > ../migration/migration.c:766:8: error: ‘start_migration’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > > 766 | if (start_migration) {
> > > | ^
> > >
> > > > Reviewed-by: Daniel P. Berrang?? <berrange@redhat.com>
> > > > Reviewed-by: Juan Quintela <quintela@redhat.com>
> > > > Signed-off-by: Peter Xu <peterx@redhat.com>
> > > > ---
> > > > migration/migration.c | 62 +++++++++++++++++++++++----
> > > > migration/migration.h | 8 ++++
> > > > migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++--
> > > > migration/postcopy-ram.h | 10 +++++
> > > > migration/ram.c | 25 ++++++++---
> > > > migration/ram.h | 4 +-
> > > > migration/savevm.c | 20 ++++-----
> > > > migration/socket.c | 22 +++++++++-
> > > > migration/socket.h | 1 +
> > > > migration/trace-events | 5 ++-
> > > > 10 files changed, 218 insertions(+), 31 deletions(-)
> > > >
> > > > diff --git a/migration/migration.c b/migration/migration.c
> > > > index ce7bb68cdc..9484fec0b2 100644
> > > > --- a/migration/migration.c
> > > > +++ b/migration/migration.c
> > > > @@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void)
> > > > mis->page_requested = NULL;
> > > > }
> > > >
> > > > + if (mis->postcopy_qemufile_dst) {
> > > > + migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
> > > > + qemu_fclose(mis->postcopy_qemufile_dst);
> > > > + mis->postcopy_qemufile_dst = NULL;
> > > > + }
> > > > +
> > > > yank_unregister_instance(MIGRATION_YANK_INSTANCE);
> > > > }
> > > >
> > > > @@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error **errp)
> > > > migration_incoming_process();
> > > > }
> > > >
> > > > +static bool migration_needs_multiple_sockets(void)
> > > > +{
> > > > + return migrate_use_multifd() || migrate_postcopy_preempt();
> > > > +}
> > > > +
> > > > void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > > > {
> > > > MigrationIncomingState *mis = migration_incoming_get_current();
> > > > Error *local_err = NULL;
> > > > bool start_migration;
> > > > + QEMUFile *f;
> > > >
> > > > if (!mis->from_src_file) {
> > > > /* The first connection (multifd may have multiple) */
> > > > - QEMUFile *f = qemu_file_new_input(ioc);
> > > > + f = qemu_file_new_input(ioc);
> > > >
> > > > if (!migration_incoming_setup(f, errp)) {
> > > > return;
> > > > @@ -730,13 +742,18 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > > >
> > > > /*
> > > > * Common migration only needs one channel, so we can start
> > > > - * right now. Multifd needs more than one channel, we wait.
> > > > + * right now. Some features need more than one channel, we wait.
> > > > */
> > > > - start_migration = !migrate_use_multifd();
> > > > + start_migration = !migration_needs_multiple_sockets();
> > > > } else {
> > > > /* Multiple connections */
> > > > - assert(migrate_use_multifd());
> > > > - start_migration = multifd_recv_new_channel(ioc, &local_err);
> > > > + assert(migration_needs_multiple_sockets());
> > > > + if (migrate_use_multifd()) {
> > > > + start_migration = multifd_recv_new_channel(ioc, &local_err);
> > > > + } else if (migrate_postcopy_preempt()) {
> > > > + f = qemu_file_new_input(ioc);
> > > > + start_migration = postcopy_preempt_new_channel(mis, f);
> > > > + }
> > >
> > > So that doesn't always set start_migration?
> >
> > Logically it should, because we asserted on
> > migration_needs_multiple_sockets(), while multifd and preempt mode are the
> > only two that may need multiple sockets. So it must go into either of
> > them.
> >
> > A fix could be like this:
> >
> > diff --git a/migration/migration.c b/migration/migration.c
> > index 76cf2a72c0..7c7e529ca7 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -753,7 +753,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > assert(migration_needs_multiple_sockets());
> > if (migrate_use_multifd()) {
> > start_migration = multifd_recv_new_channel(ioc, &local_err);
> > - } else if (migrate_postcopy_preempt()) {
> > + } else {
> > + assert(migrate_postcopy_preempt());
> > f = qemu_file_new_input(ioc);
> > start_migration = postcopy_preempt_new_channel(mis, f);
> > }
> >
> > Or we simply set start_migration=false as initial value.
> >
> > Should I repost the series?
>
> No just post a fixup and I'll merge it.
Attached, thanks.
--
Peter Xu
[-- Attachment #2: 0001-fixup-migration-Postcopy-preemption-preparation-on-c.patch --]
[-- Type: text/plain, Size: 1041 bytes --]
From af276d410e140b8d4292dc476163f2734cf089c1 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Tue, 19 Jul 2022 11:38:32 -0400
Subject: [PATCH] fixup! migration: Postcopy preemption preparation on channel
creation
Content-type: text/plain
Signed-off-by: Peter Xu <peterx@redhat.com>
---
migration/migration.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/migration/migration.c b/migration/migration.c
index 76cf2a72c0..7c7e529ca7 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -753,7 +753,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
assert(migration_needs_multiple_sockets());
if (migrate_use_multifd()) {
start_migration = multifd_recv_new_channel(ioc, &local_err);
- } else if (migrate_postcopy_preempt()) {
+ } else {
+ assert(migrate_postcopy_preempt());
f = qemu_file_new_input(ioc);
start_migration = postcopy_preempt_new_channel(mis, f);
}
--
2.32.0
^ permalink raw reply related [flat|nested] 22+ messages in thread
* Re: [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation
2022-07-19 15:39 ` Peter Xu
@ 2022-07-19 16:06 ` Dr. David Alan Gilbert
0 siblings, 0 replies; 22+ messages in thread
From: Dr. David Alan Gilbert @ 2022-07-19 16:06 UTC (permalink / raw)
To: Peter Xu
Cc: qemu-devel, Juan Quintela, Leonardo Bras Soares Passos,
Manish Mishra, Daniel P . Berrange
* Peter Xu (peterx@redhat.com) wrote:
> On Tue, Jul 19, 2022 at 04:31:20PM +0100, Dr. David Alan Gilbert wrote:
> > * Peter Xu (peterx@redhat.com) wrote:
> > > On Tue, Jul 19, 2022 at 04:15:49PM +0100, Dr. David Alan Gilbert wrote:
> > > > * Peter Xu (peterx@redhat.com) wrote:
> > > > > Create a new socket for postcopy to be prepared to send postcopy requested
> > > > > pages via this specific channel, so as to not get blocked by precopy pages.
> > > > >
> > > > > A new thread is also created on dest qemu to receive data from this new channel
> > > > > based on the ram_load_postcopy() routine.
> > > > >
> > > > > The ram_load_postcopy(POSTCOPY) branch and the thread has not started to
> > > > > function, and that'll be done in follow up patches.
> > > > >
> > > > > Cleanup the new sockets on both src/dst QEMUs, meanwhile look after the new
> > > > > thread too to make sure it'll be recycled properly.
> > > >
> > > > I'm hitting a CI failure here:
> > > > https://gitlab.com/dagrh/qemu/-/jobs/2741659845
> > > >
> > > > c.o -c ../migration/migration.c
> > > > ../migration/migration.c: In function ‘migration_ioc_process_incoming’:
> > > > ../migration/migration.c:766:8: error: ‘start_migration’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > > > 766 | if (start_migration) {
> > > > | ^
> > > >
> > > > > Reviewed-by: Daniel P. Berrang?? <berrange@redhat.com>
> > > > > Reviewed-by: Juan Quintela <quintela@redhat.com>
> > > > > Signed-off-by: Peter Xu <peterx@redhat.com>
> > > > > ---
> > > > > migration/migration.c | 62 +++++++++++++++++++++++----
> > > > > migration/migration.h | 8 ++++
> > > > > migration/postcopy-ram.c | 92 ++++++++++++++++++++++++++++++++++++++--
> > > > > migration/postcopy-ram.h | 10 +++++
> > > > > migration/ram.c | 25 ++++++++---
> > > > > migration/ram.h | 4 +-
> > > > > migration/savevm.c | 20 ++++-----
> > > > > migration/socket.c | 22 +++++++++-
> > > > > migration/socket.h | 1 +
> > > > > migration/trace-events | 5 ++-
> > > > > 10 files changed, 218 insertions(+), 31 deletions(-)
> > > > >
> > > > > diff --git a/migration/migration.c b/migration/migration.c
> > > > > index ce7bb68cdc..9484fec0b2 100644
> > > > > --- a/migration/migration.c
> > > > > +++ b/migration/migration.c
> > > > > @@ -321,6 +321,12 @@ void migration_incoming_state_destroy(void)
> > > > > mis->page_requested = NULL;
> > > > > }
> > > > >
> > > > > + if (mis->postcopy_qemufile_dst) {
> > > > > + migration_ioc_unregister_yank_from_file(mis->postcopy_qemufile_dst);
> > > > > + qemu_fclose(mis->postcopy_qemufile_dst);
> > > > > + mis->postcopy_qemufile_dst = NULL;
> > > > > + }
> > > > > +
> > > > > yank_unregister_instance(MIGRATION_YANK_INSTANCE);
> > > > > }
> > > > >
> > > > > @@ -714,15 +720,21 @@ void migration_fd_process_incoming(QEMUFile *f, Error **errp)
> > > > > migration_incoming_process();
> > > > > }
> > > > >
> > > > > +static bool migration_needs_multiple_sockets(void)
> > > > > +{
> > > > > + return migrate_use_multifd() || migrate_postcopy_preempt();
> > > > > +}
> > > > > +
> > > > > void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > > > > {
> > > > > MigrationIncomingState *mis = migration_incoming_get_current();
> > > > > Error *local_err = NULL;
> > > > > bool start_migration;
> > > > > + QEMUFile *f;
> > > > >
> > > > > if (!mis->from_src_file) {
> > > > > /* The first connection (multifd may have multiple) */
> > > > > - QEMUFile *f = qemu_file_new_input(ioc);
> > > > > + f = qemu_file_new_input(ioc);
> > > > >
> > > > > if (!migration_incoming_setup(f, errp)) {
> > > > > return;
> > > > > @@ -730,13 +742,18 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > > > >
> > > > > /*
> > > > > * Common migration only needs one channel, so we can start
> > > > > - * right now. Multifd needs more than one channel, we wait.
> > > > > + * right now. Some features need more than one channel, we wait.
> > > > > */
> > > > > - start_migration = !migrate_use_multifd();
> > > > > + start_migration = !migration_needs_multiple_sockets();
> > > > > } else {
> > > > > /* Multiple connections */
> > > > > - assert(migrate_use_multifd());
> > > > > - start_migration = multifd_recv_new_channel(ioc, &local_err);
> > > > > + assert(migration_needs_multiple_sockets());
> > > > > + if (migrate_use_multifd()) {
> > > > > + start_migration = multifd_recv_new_channel(ioc, &local_err);
> > > > > + } else if (migrate_postcopy_preempt()) {
> > > > > + f = qemu_file_new_input(ioc);
> > > > > + start_migration = postcopy_preempt_new_channel(mis, f);
> > > > > + }
> > > >
> > > > So that doesn't always set start_migration?
> > >
> > > Logically it should, because we asserted on
> > > migration_needs_multiple_sockets(), while multifd and preempt mode are the
> > > only two that may need multiple sockets. So it must go into either of
> > > them.
> > >
> > > A fix could be like this:
> > >
> > > diff --git a/migration/migration.c b/migration/migration.c
> > > index 76cf2a72c0..7c7e529ca7 100644
> > > --- a/migration/migration.c
> > > +++ b/migration/migration.c
> > > @@ -753,7 +753,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> > > assert(migration_needs_multiple_sockets());
> > > if (migrate_use_multifd()) {
> > > start_migration = multifd_recv_new_channel(ioc, &local_err);
> > > - } else if (migrate_postcopy_preempt()) {
> > > + } else {
> > > + assert(migrate_postcopy_preempt());
> > > f = qemu_file_new_input(ioc);
> > > start_migration = postcopy_preempt_new_channel(mis, f);
> > > }
> > >
> > > Or we simply set start_migration=false as initial value.
> > >
> > > Should I repost the series?
> >
> > No just post a fixup and I'll merge it.
>
> Attached, thanks.
Thanks,
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> --
> Peter Xu
> From af276d410e140b8d4292dc476163f2734cf089c1 Mon Sep 17 00:00:00 2001
> From: Peter Xu <peterx@redhat.com>
> Date: Tue, 19 Jul 2022 11:38:32 -0400
> Subject: [PATCH] fixup! migration: Postcopy preemption preparation on channel
> creation
> Content-type: text/plain
>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> migration/migration.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 76cf2a72c0..7c7e529ca7 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -753,7 +753,8 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
> assert(migration_needs_multiple_sockets());
> if (migrate_use_multifd()) {
> start_migration = multifd_recv_new_channel(ioc, &local_err);
> - } else if (migrate_postcopy_preempt()) {
> + } else {
> + assert(migrate_postcopy_preempt());
> f = qemu_file_new_input(ioc);
> start_migration = postcopy_preempt_new_channel(mis, f);
> }
> --
> 2.32.0
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
^ permalink raw reply [flat|nested] 22+ messages in thread
end of thread, other threads:[~2022-07-19 16:09 UTC | newest]
Thread overview: 22+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-07-07 18:53 [PATCH v9 00/14] migration: Postcopy Preemption Peter Xu
2022-07-07 18:53 ` [PATCH v9 01/14] migration: Add postcopy-preempt capability Peter Xu
2022-07-07 18:55 ` [PATCH v9 02/14] migration: Postcopy preemption preparation on channel creation Peter Xu
2022-07-19 15:15 ` Dr. David Alan Gilbert
2022-07-19 15:25 ` Peter Xu
2022-07-19 15:31 ` Dr. David Alan Gilbert
2022-07-19 15:39 ` Peter Xu
2022-07-19 16:06 ` Dr. David Alan Gilbert
2022-07-07 18:55 ` [PATCH v9 03/14] migration: Postcopy preemption enablement Peter Xu
2022-07-07 18:55 ` [PATCH v9 04/14] migration: Postcopy recover with preempt enabled Peter Xu
2022-07-07 18:55 ` [PATCH v9 05/14] migration: Create the postcopy preempt channel asynchronously Peter Xu
2022-07-07 18:55 ` [PATCH v9 06/14] migration: Add property x-postcopy-preempt-break-huge Peter Xu
2022-07-07 18:55 ` [PATCH v9 07/14] migration: Add helpers to detect TLS capability Peter Xu
2022-07-07 18:55 ` [PATCH v9 08/14] migration: Export tls-[creds|hostname|authz] params to cmdline too Peter Xu
2022-07-07 18:55 ` [PATCH v9 09/14] migration: Enable TLS for preempt channel Peter Xu
2022-07-07 18:55 ` [PATCH v9 10/14] migration: Respect postcopy request order in preemption mode Peter Xu
2022-07-07 18:55 ` [PATCH v9 11/14] tests: Move MigrateCommon upper Peter Xu
2022-07-07 18:55 ` [PATCH v9 12/14] tests: Add postcopy tls migration test Peter Xu
2022-07-13 11:25 ` Dr. David Alan Gilbert
2022-07-07 18:55 ` [PATCH v9 13/14] tests: Add postcopy tls recovery " Peter Xu
2022-07-07 18:55 ` [PATCH v9 14/14] tests: Add postcopy preempt tests Peter Xu
2022-07-19 13:50 ` [PATCH v9 00/14] migration: Postcopy Preemption Dr. David Alan Gilbert
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