From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40492) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZHsRE-000751-0G for qemu-devel@nongnu.org; Wed, 22 Jul 2015 07:43:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZHsRC-0005jz-1l for qemu-devel@nongnu.org; Wed, 22 Jul 2015 07:43:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56762) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZHsRB-0005jq-SI for qemu-devel@nongnu.org; Wed, 22 Jul 2015 07:43:49 -0400 From: Stefan Hajnoczi Date: Wed, 22 Jul 2015 12:43:39 +0100 Message-Id: <1437565425-29861-2-git-send-email-stefanha@redhat.com> In-Reply-To: <1437565425-29861-1-git-send-email-stefanha@redhat.com> References: <1437565425-29861-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PULL v2 for-2.4 v2 1/7] mirror: Speed up bitmap initial scanning List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Peter Maydell , Fam Zheng , Stefan Hajnoczi From: Fam Zheng Limiting to sectors_per_chunk for each bdrv_is_allocated_above is slow, because the underlying protocol driver would issue much more queries than necessary. We should coalesce the query. Signed-off-by: Fam Zheng Reviewed-by: Stefan Hajnoczi Message-id: <1436413678-7114-4-git-send-email-famz@redhat.com> Signed-off-by: Stefan Hajnoczi --- block/mirror.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index 323f747..fc4d8f5 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -388,7 +388,7 @@ static void coroutine_fn mirror_run(void *opaque) MirrorBlockJob *s = opaque; MirrorExitData *data; BlockDriverState *bs = s->common.bs; - int64_t sector_num, end, sectors_per_chunk, length; + int64_t sector_num, end, length; uint64_t last_pause_ns; BlockDriverInfo bdi; char backing_filename[2]; /* we only need 2 characters because we are only @@ -442,7 +442,6 @@ static void coroutine_fn mirror_run(void *opaque) goto immediate_exit; } - sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; mirror_free_init(s); last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); @@ -450,7 +449,9 @@ static void coroutine_fn mirror_run(void *opaque) /* First part, loop on the sectors and initialize the dirty bitmap. */ BlockDriverState *base = s->base; for (sector_num = 0; sector_num < end; ) { - int64_t next = (sector_num | (sectors_per_chunk - 1)) + 1; + /* Just to make sure we are not exceeding int limit. */ + int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS, + end - sector_num); int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); if (now - last_pause_ns > SLICE_TIME) { @@ -462,8 +463,7 @@ static void coroutine_fn mirror_run(void *opaque) goto immediate_exit; } - ret = bdrv_is_allocated_above(bs, base, - sector_num, next - sector_num, &n); + ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n); if (ret < 0) { goto immediate_exit; @@ -472,10 +472,8 @@ static void coroutine_fn mirror_run(void *opaque) assert(n > 0); if (ret == 1) { bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n); - sector_num = next; - } else { - sector_num += n; } + sector_num += n; } } -- 2.4.3