From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33009) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aP8md-0005iM-Dw for qemu-devel@nongnu.org; Fri, 29 Jan 2016 08:08:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aP8mZ-0007t6-4W for qemu-devel@nongnu.org; Fri, 29 Jan 2016 08:08:15 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48315) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aP8mY-0007t0-RZ for qemu-devel@nongnu.org; Fri, 29 Jan 2016 08:08:11 -0500 Date: Fri, 29 Jan 2016 13:08:00 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20160129130759.GI2410@work-vm> References: <1451372975-5048-1-git-send-email-zhang.zhanghailiang@huawei.com> <1451372975-5048-11-git-send-email-zhang.zhanghailiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1451372975-5048-11-git-send-email-zhang.zhanghailiang@huawei.com> 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: zhanghailiang 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 * 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 as long as there are no negative values when it's declared; so it looks safe in practice. Reviewed-by: Dr. David Alan Gilbert > + 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