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COLO: Introduce checkpointing protocol 

We need communications protocol of user-defined to control
the checkpointing process.

The new checkpointing 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 <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Cc: Eric Blake <eblake@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Amit Shah <amit@amitshah.net>
This commit is contained in:
zhanghailiang 2016-10-27 14:42:57 +08:00 committed by Amit Shah
parent 56ba83d2a8
commit 4f97558e10
3 changed files with 226 additions and 2 deletions
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201
migration/colo.c
View File

@ -15,6 +15,7 @@
#include "migration/colo.h"
#include "trace.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
bool colo_supported(void)
{
@ -35,22 +36,147 @@ bool migration_incoming_in_colo_state(void)
return mis && (mis->state == MIGRATION_STATUS_COLO);
}
static void colo_send_message(QEMUFile *f, COLOMessage msg,
Error **errp)
{
int ret;
if (msg >= COLO_MESSAGE__MAX) {
error_setg(errp, "%s: Invalid message", __func__);
return;
}
qemu_put_be32(f, msg);
qemu_fflush(f);
ret = qemu_file_get_error(f);
if (ret < 0) {
error_setg_errno(errp, -ret, "Can't send COLO message");
}
trace_colo_send_message(COLOMessage_lookup[msg]);
}
static COLOMessage colo_receive_message(QEMUFile *f, Error **errp)
{
COLOMessage msg;
int ret;
msg = qemu_get_be32(f);
ret = qemu_file_get_error(f);
if (ret < 0) {
error_setg_errno(errp, -ret, "Can't receive COLO message");
return msg;
}
if (msg >= COLO_MESSAGE__MAX) {
error_setg(errp, "%s: Invalid message", __func__);
return msg;
}
trace_colo_receive_message(COLOMessage_lookup[msg]);
return msg;
}
static void colo_receive_check_message(QEMUFile *f, COLOMessage expect_msg,
Error **errp)
{
COLOMessage msg;
Error *local_err = NULL;
msg = colo_receive_message(f, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
if (msg != expect_msg) {
error_setg(errp, "Unexpected COLO message %d, expected %d",
msg, expect_msg);
}
}
static int colo_do_checkpoint_transaction(MigrationState *s)
{
Error *local_err = NULL;
colo_send_message(s->to_dst_file, COLO_MESSAGE_CHECKPOINT_REQUEST,
&local_err);
if (local_err) {
goto out;
}
colo_receive_check_message(s->rp_state.from_dst_file,
COLO_MESSAGE_CHECKPOINT_REPLY, &local_err);
if (local_err) {
goto out;
}
/* TODO: suspend and save vm state to colo buffer */
colo_send_message(s->to_dst_file, COLO_MESSAGE_VMSTATE_SEND, &local_err);
if (local_err) {
goto out;
}
/* TODO: send vmstate to Secondary */
colo_receive_check_message(s->rp_state.from_dst_file,
COLO_MESSAGE_VMSTATE_RECEIVED, &local_err);
if (local_err) {
goto out;
}
colo_receive_check_message(s->rp_state.from_dst_file,
COLO_MESSAGE_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_receive_check_message(s->rp_state.from_dst_file,
COLO_MESSAGE_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) {
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);
}
if (s->rp_state.from_dst_file) {
qemu_fclose(s->rp_state.from_dst_file);
}
@ -65,9 +191,33 @@ void migrate_start_colo_process(MigrationState *s)
qemu_mutex_lock_iothread();
}
static void colo_wait_handle_message(QEMUFile *f, int *checkpoint_request,
Error **errp)
{
COLOMessage msg;
Error *local_err = NULL;
msg = colo_receive_message(f, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
switch (msg) {
case COLO_MESSAGE_CHECKPOINT_REQUEST:
*checkpoint_request = 1;
break;
default:
*checkpoint_request = 0;
error_setg(errp, "Got unknown COLO message: %d", msg);
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_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
&local_err);
if (local_err) {
goto out;
}
while (mis->state == MIGRATION_STATUS_COLO) {
int request;
colo_wait_handle_message(mis->from_src_file, &request, &local_err);
if (local_err) {
goto out;
}
assert(request);
/* FIXME: This is unnecessary for periodic checkpoint mode */
colo_send_message(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_REPLY,
&local_err);
if (local_err) {
goto out;
}
colo_receive_check_message(mis->from_src_file,
COLO_MESSAGE_VMSTATE_SEND, &local_err);
if (local_err) {
goto out;
}
/* TODO: read migration data into colo buffer */
colo_send_message(mis->to_src_file, COLO_MESSAGE_VMSTATE_RECEIVED,
&local_err);
if (local_err) {
goto out;
}
/* TODO: load vm state */
colo_send_message(mis->to_src_file, COLO_MESSAGE_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);
}

2
migration/trace-events
View File

@ -210,3 +210,5 @@ migration_tls_incoming_handshake_complete(void) ""
# migration/colo.c
colo_vm_state_change(const char *old, const char *new) "Change '%s' => '%s'"
colo_send_message(const char *msg) "Send '%s' message"
colo_receive_message(const char *msg) "Receive '%s' message"

25
qapi-schema.json
View File

@ -787,6 +787,31 @@
{ 'command': 'migrate-start-postcopy' }
##
# @COLOMessage
#
# The message transmission between Primary side and Secondary side.
#
# @checkpoint-ready: Secondary VM (SVM) is ready for checkpointing
#
# @checkpoint-request: Primary VM (PVM) tells SVM to prepare for 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: 2.8
##
{ 'enum': 'COLOMessage',
'data': [ 'checkpoint-ready', 'checkpoint-request', 'checkpoint-reply',
'vmstate-send', 'vmstate-size', 'vmstate-received',
'vmstate-loaded' ] }
# @MouseInfo:
#
# Information about a mouse device.