From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33779) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aPRGE-0000la-A4 for qemu-devel@nongnu.org; Sat, 30 Jan 2016 03:52:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aPRGB-00079Z-1V for qemu-devel@nongnu.org; Sat, 30 Jan 2016 03:52:02 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:35157) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aPRG9-000796-Tg for qemu-devel@nongnu.org; Sat, 30 Jan 2016 03:51:58 -0500 References: <1451372975-5048-1-git-send-email-zhang.zhanghailiang@huawei.com> <1451372975-5048-11-git-send-email-zhang.zhanghailiang@huawei.com> <20160129130759.GI2410@work-vm> From: Hailiang Zhang Message-ID: <56AC798C.3000009@huawei.com> Date: Sat, 30 Jan 2016 16:51:24 +0800 MIME-Version: 1.0 In-Reply-To: <20160129130759.GI2410@work-vm> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH COLO-Frame v13 10/39] COLO: Implement colo checkpoint protocol List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: xiecl.fnst@cn.fujitsu.com, lizhijian@cn.fujitsu.com, quintela@redhat.com, Markus Armbruster , yunhong.jiang@intel.com, eddie.dong@intel.com, peter.huangpeng@huawei.com, qemu-devel@nongnu.org, arei.gonglei@huawei.com, stefanha@redhat.com, amit.shah@redhat.com, zhangchen.fnst@cn.fujitsu.com, hongyang.yang@easystack.cn On 2016/1/29 21:08, Dr. David Alan Gilbert wrote: > * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote: >> We need communications protocol of user-defined to control the checkpoint >> process. >> >> The new checkpoint request is started by Primary VM, and the interactive process >> like below: >> Checkpoint synchronizing points: >> >> Primary Secondary >> initial work >> 'checkpoint-ready' <-------------------- @ >> >> 'checkpoint-request' @ --------------------> >> Suspend (Only in hybrid mode) >> 'checkpoint-reply' <-------------------- @ >> Suspend&Save state >> 'vmstate-send' @ --------------------> >> Send state Receive state >> 'vmstate-received' <-------------------- @ >> Release packets Load state >> 'vmstate-load' <-------------------- @ >> Resume Resume (Only in hybrid mode) >> >> Start Comparing (Only in hybrid mode) >> NOTE: >> 1) '@' who sends the message >> 2) Every sync-point is synchronized by two sides with only >> one handshake(single direction) for low-latency. >> If more strict synchronization is required, a opposite direction >> sync-point should be added. >> 3) Since sync-points are single direction, the remote side may >> go forward a lot when this side just receives the sync-point. >> 4) For now, we only support 'periodic' checkpoint, for which >> the Secondary VM is not running, later we will support 'hybrid' mode. >> >> Signed-off-by: zhanghailiang >> Signed-off-by: Li Zhijian >> Signed-off-by: Gonglei >> Cc: Eric Blake >> Cc: Markus Armbruster >> Cc: Dr. David Alan Gilbert >> --- >> v13: >> - Refactor colo command related helper functions, use 'Error **errp' parameter >> instead of return value to indicate success or failure. >> - Fix some other comments from Markus. >> >> v12: >> - Rename colo_ctl_put() to colo_put_cmd() >> - Rename colo_ctl_get() to colo_get_check_cmd() and drop >> the third parameter >> - Rename colo_ctl_get_cmd() to colo_get_cmd() >> - Remove useless 'invalid' member for COLOcommand enum. >> v11: >> - Add missing 'checkpoint-ready' communication in comment. >> - Use parameter to return 'value' for colo_ctl_get() (Dave's suggestion) >> - Fix trace for colo_ctl_get() to trace command and value both >> v10: >> - Rename enum COLOCmd to COLOCommand (Eric's suggestion). >> - Remove unused 'ram-steal' >> --- >> migration/colo.c | 201 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- >> qapi-schema.json | 25 +++++++ >> trace-events | 2 + >> 3 files changed, 226 insertions(+), 2 deletions(-) >> >> diff --git a/migration/colo.c b/migration/colo.c >> index 65ac0c9..c76e1fa 100644 >> --- a/migration/colo.c >> +++ b/migration/colo.c >> @@ -10,6 +10,7 @@ >> * later. See the COPYING file in the top-level directory. >> */ >> >> +#include >> #include "sysemu/sysemu.h" >> #include "migration/colo.h" >> #include "trace.h" >> @@ -34,22 +35,147 @@ bool migration_incoming_in_colo_state(void) >> return mis && (mis->state == MIGRATION_STATUS_COLO); >> } >> >> +static void colo_put_cmd(QEMUFile *f, COLOCommand cmd, >> + Error **errp) >> +{ >> + int ret; >> + >> + if (cmd >= COLO_COMMAND__MAX) { >> + error_setg(errp, "%s: Invalid cmd", __func__); >> + return; >> + } >> + qemu_put_be32(f, cmd); >> + qemu_fflush(f); >> + >> + ret = qemu_file_get_error(f); >> + if (ret < 0) { >> + error_setg_errno(errp, -ret, "Can't put COLO command"); >> + } >> + trace_colo_put_cmd(COLOCommand_lookup[cmd]); >> +} >> + >> +static COLOCommand colo_get_cmd(QEMUFile *f, Error **errp) >> +{ >> + COLOCommand cmd; >> + int ret; >> + >> + cmd = qemu_get_be32(f); >> + ret = qemu_file_get_error(f); >> + if (ret < 0) { >> + error_setg_errno(errp, -ret, "Can't get COLO command"); >> + return cmd; >> + } >> + if (cmd >= COLO_COMMAND__MAX) { > > I'm not sure this is guaranteed to do the right thing if the value > read was negative and converted to the enum; it seems to depend > a bit on the compiler as to whether an enum is signed or not; > but it seems the normal behaviour is for the enum to be unsigned Interesting question, we can define a negative enumeration-constant, enum test { TEST_A = -2, TEST_B = 0, } value; So i suppose an enum is signed, and ISO C standard (c99 6.4.4.3) states that the enumeration constants are of type int. But it seems that gcc does not follow this standard strictly, i got the exact answer from its specification: https://gcc.gnu.org/onlinedocs/gcc/Structures-unions-enumerations-and-bit-fields-implementation.html#Structures-unions-enumerations-and-bit-fields-implementation "Normally, the type is unsigned int if there are no negative values in the enumeration, otherwise int." > as long as there are no negative values when it's declared; so it looks > safe in practice. > > Reviewed-by: Dr. David Alan Gilbert > Thanks, Hailiang >> + error_setg(errp, "%s: Invalid cmd", __func__); >> + return cmd; >> + } >> + trace_colo_get_cmd(COLOCommand_lookup[cmd]); >> + return cmd; >> +} >> + >> +static void colo_get_check_cmd(QEMUFile *f, COLOCommand expect_cmd, >> + Error **errp) >> +{ >> + COLOCommand cmd; >> + Error *local_err = NULL; >> + >> + cmd = colo_get_cmd(f, &local_err); >> + if (local_err) { >> + error_propagate(errp, local_err); >> + return; >> + } >> + if (cmd != expect_cmd) { >> + error_setg(errp, "Unexpected COLO command %d, expected %d", >> + expect_cmd, cmd); >> + } >> +} >> + >> +static int colo_do_checkpoint_transaction(MigrationState *s) >> +{ >> + Error *local_err = NULL; >> + >> + colo_put_cmd(s->to_dst_file, COLO_COMMAND_CHECKPOINT_REQUEST, >> + &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + colo_get_check_cmd(s->rp_state.from_dst_file, >> + COLO_COMMAND_CHECKPOINT_REPLY, &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + /* TODO: suspend and save vm state to colo buffer */ >> + >> + colo_put_cmd(s->to_dst_file, COLO_COMMAND_VMSTATE_SEND, &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + /* TODO: send vmstate to Secondary */ >> + >> + colo_get_check_cmd(s->rp_state.from_dst_file, >> + COLO_COMMAND_VMSTATE_RECEIVED, &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + colo_get_check_cmd(s->rp_state.from_dst_file, >> + COLO_COMMAND_VMSTATE_LOADED, &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + /* TODO: resume Primary */ >> + >> + return 0; >> +out: >> + if (local_err) { >> + error_report_err(local_err); >> + } >> + return -EINVAL; >> +} >> + >> static void colo_process_checkpoint(MigrationState *s) >> { >> + Error *local_err = NULL; >> + int ret; >> + >> s->rp_state.from_dst_file = qemu_file_get_return_path(s->to_dst_file); >> if (!s->rp_state.from_dst_file) { >> error_report("Open QEMUFile from_dst_file failed"); >> goto out; >> } >> >> + /* >> + * Wait for Secondary finish loading vm states and enter COLO >> + * restore. >> + */ >> + colo_get_check_cmd(s->rp_state.from_dst_file, >> + COLO_COMMAND_CHECKPOINT_READY, &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> qemu_mutex_lock_iothread(); >> vm_start(); >> qemu_mutex_unlock_iothread(); >> trace_colo_vm_state_change("stop", "run"); >> >> - /*TODO: COLO checkpoint savevm loop*/ >> + while (s->state == MIGRATION_STATUS_COLO) { >> + /* start a colo checkpoint */ >> + ret = colo_do_checkpoint_transaction(s); >> + if (ret < 0) { >> + goto out; >> + } >> + } >> >> out: >> + /* Throw the unreported error message after exited from loop */ >> + if (local_err) { >> + error_report_err(local_err); >> + } >> migrate_set_state(&s->state, MIGRATION_STATUS_COLO, >> MIGRATION_STATUS_COMPLETED); >> >> @@ -67,9 +193,33 @@ void migrate_start_colo_process(MigrationState *s) >> qemu_mutex_lock_iothread(); >> } >> >> +static void colo_wait_handle_cmd(QEMUFile *f, int *checkpoint_request, >> + Error **errp) >> +{ >> + COLOCommand cmd; >> + Error *local_err = NULL; >> + >> + cmd = colo_get_cmd(f, &local_err); >> + if (local_err) { >> + error_propagate(errp, local_err); >> + return; >> + } >> + >> + switch (cmd) { >> + case COLO_COMMAND_CHECKPOINT_REQUEST: >> + *checkpoint_request = 1; >> + break; >> + default: >> + *checkpoint_request = 0; >> + error_setg(errp, "Got unknown COLO command: %d", cmd); >> + break; >> + } >> +} >> + >> void *colo_process_incoming_thread(void *opaque) >> { >> MigrationIncomingState *mis = opaque; >> + Error *local_err = NULL; >> >> migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE, >> MIGRATION_STATUS_COLO); >> @@ -85,9 +235,56 @@ void *colo_process_incoming_thread(void *opaque) >> */ >> qemu_file_set_blocking(mis->from_src_file, true); >> >> - /* TODO: COLO checkpoint restore loop */ >> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_CHECKPOINT_READY, >> + &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + while (mis->state == MIGRATION_STATUS_COLO) { >> + int request; >> + >> + colo_wait_handle_cmd(mis->from_src_file, &request, &local_err); >> + if (local_err) { >> + goto out; >> + } >> + assert(request); >> + /* FIXME: This is unnecessary for periodic checkpoint mode */ >> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_CHECKPOINT_REPLY, >> + &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + colo_get_check_cmd(mis->from_src_file, >> + COLO_COMMAND_VMSTATE_SEND, &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + /* TODO: read migration data into colo buffer */ >> + >> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_VMSTATE_RECEIVED, >> + &local_err); >> + if (local_err) { >> + goto out; >> + } >> + >> + /* TODO: load vm state */ >> + >> + colo_put_cmd(mis->to_src_file, COLO_COMMAND_VMSTATE_LOADED, >> + &local_err); >> + if (local_err) { >> + goto out; >> + } >> + } >> >> out: >> + /* Throw the unreported error message after exited from loop */ >> + if (local_err) { >> + error_report_err(local_err); >> + } >> + >> if (mis->to_src_file) { >> qemu_fclose(mis->to_src_file); >> } >> diff --git a/qapi-schema.json b/qapi-schema.json >> index 6eefad2..4ea4108 100644 >> --- a/qapi-schema.json >> +++ b/qapi-schema.json >> @@ -718,6 +718,31 @@ >> { 'command': 'migrate-start-postcopy' } >> >> ## >> +# @COLOCommand >> +# >> +# The commands for COLO fault tolerance >> +# >> +# @checkpoint-ready: SVM is ready for checkpointing >> +# >> +# @checkpoint-request: PVM tells SVM to prepare for new checkpointing >> +# >> +# @checkpoint-reply: SVM gets PVM's checkpoint request >> +# >> +# @vmstate-send: VM's state will be sent by PVM. >> +# >> +# @vmstate-size: The total size of VMstate. >> +# >> +# @vmstate-received: VM's state has been received by SVM. >> +# >> +# @vmstate-loaded: VM's state has been loaded by SVM. >> +# >> +# Since: 2.6 >> +## >> +{ 'enum': 'COLOCommand', >> + 'data': [ 'checkpoint-ready', 'checkpoint-request', 'checkpoint-reply', >> + 'vmstate-send', 'vmstate-size', 'vmstate-received', >> + 'vmstate-loaded' ] } >> + >> # @MouseInfo: >> # >> # Information about a mouse device. >> diff --git a/trace-events b/trace-events >> index 57ddc8f..51b2305 100644 >> --- a/trace-events >> +++ b/trace-events >> @@ -1581,6 +1581,8 @@ postcopy_ram_incoming_cleanup_join(void) "" >> >> # migration/colo.c >> colo_vm_state_change(const char *old, const char *new) "Change '%s' => '%s'" >> +colo_put_cmd(const char *msg) "Send '%s' cmd" >> +colo_get_cmd(const char *msg) "Receive '%s' cmd" >> >> # kvm-all.c >> kvm_ioctl(int type, void *arg) "type 0x%x, arg %p" >> -- >> 1.8.3.1 >> >> > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > . >