From bdffb31d8eece1cbd4d88f136daccfe1f93a1bf6 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 9 Nov 2016 17:20:08 +0100 Subject: mirror: do not flush every time the disks are synced 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 Message-id: 20161109162008.27287-2-pbonzini@redhat.com Signed-off-by: Jeff Cody --- block/mirror.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) (limited to 'block') diff --git a/block/mirror.c b/block/mirror.c index 62ac87f0c4..301ba9219a 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -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; } -- cgit v1.2.3