OpenE2K/qemu-e2k
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mirror: do not flush every time the disks are synced

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This puts a huge strain on the disks when there are many concurrent
migrations.  With this patch we only flush twice: just before issuing
the event, and just before pivoting to the destination.  If management
will complete the job close to the BLOCK_JOB_READY event, the cost of
the second flush should be small anyway.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161109162008.27287-2-pbonzini@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-11-09 17:20:08 +01:00 committed by Jeff Cody
parent 4e504535c1
commit bdffb31d8e
1 changed files with 25 additions and 15 deletions
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40
block/mirror.c
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@ -615,6 +615,20 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
return 0;
}
/* Called when going out of the streaming phase to flush the bulk of the
* data to the medium, or just before completing.
*/
static int mirror_flush(MirrorBlockJob *s)
{
int ret = blk_flush(s->target);
if (ret < 0) {
if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) {
s->ret = ret;
}
}
return ret;
}
static void coroutine_fn mirror_run(void *opaque)
{
MirrorBlockJob *s = opaque;
@ -727,27 +741,23 @@ static void coroutine_fn mirror_run(void *opaque)
should_complete = false;
if (s->in_flight == 0 && cnt == 0) {
trace_mirror_before_flush(s);
ret = blk_flush(s->target);
if (ret < 0) {
if (mirror_error_action(s, false, -ret) ==
BLOCK_ERROR_ACTION_REPORT) {
goto immediate_exit;
if (!s->synced) {
if (mirror_flush(s) < 0) {
/* Go check s->ret. */
continue;
}
} else {
/* We're out of the streaming phase. From now on, if the job
* is cancelled we will actually complete all pending I/O and
* report completion. This way, block-job-cancel will leave
* the target in a consistent state.
*/
if (!s->synced) {
block_job_event_ready(&s->common);
s->synced = true;
}
should_complete = s->should_complete ||
block_job_is_cancelled(&s->common);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
block_job_event_ready(&s->common);
s->synced = true;
}
should_complete = s->should_complete ||
block_job_is_cancelled(&s->common);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
}
if (cnt == 0 && should_complete) {
@ -765,7 +775,7 @@ static void coroutine_fn mirror_run(void *opaque)
bdrv_drained_begin(bs);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
if (cnt > 0) {
if (cnt > 0 || mirror_flush(s) < 0) {
bdrv_drained_end(bs);
continue;
}