From 4b5004d9fc5b7d8e4447dc81c2f26477c2d590f7 Mon Sep 17 00:00:00 2001 From: "Denis V. Lunev" Date: Thu, 14 Jul 2016 16:33:29 +0300 Subject: [PATCH] mirror: improve performance of mirroring of empty disk We should not take into account zero blocks for delay calculations. They are not read and thus IO throttling is not required. In the other case VM migration with 16 Tb QCOW2 disk with 4 Gb of data takes days. Signed-off-by: Denis V. Lunev Reviewed-by: Vladimir Sementsov-Ogievskiy Reviewed-by: Fam Zheng Message-id: 1468503209-19498-9-git-send-email-den@openvz.org CC: Stefan Hajnoczi CC: Kevin Wolf CC: Max Reitz CC: Jeff Cody CC: Eric Blake Signed-off-by: Jeff Cody --- block/mirror.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index 0262b03..f78186d 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -323,6 +323,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) int nb_chunks = 1; int64_t end = s->bdev_length / BDRV_SECTOR_SIZE; int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; + bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); sector_num = hbitmap_iter_next(&s->hbi); if (sector_num < 0) { @@ -373,7 +374,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) bitmap_set(s->in_flight_bitmap, sector_num / sectors_per_chunk, nb_chunks); while (nb_chunks > 0 && sector_num < end) { int ret; - int io_sectors; + int io_sectors, io_sectors_acct; BlockDriverState *file; enum MirrorMethod { MIRROR_METHOD_COPY, @@ -410,12 +411,17 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) switch (mirror_method) { case MIRROR_METHOD_COPY: io_sectors = mirror_do_read(s, sector_num, io_sectors); + io_sectors_acct = io_sectors; break; case MIRROR_METHOD_ZERO: - mirror_do_zero_or_discard(s, sector_num, io_sectors, false); - break; case MIRROR_METHOD_DISCARD: - mirror_do_zero_or_discard(s, sector_num, io_sectors, true); + mirror_do_zero_or_discard(s, sector_num, io_sectors, + mirror_method == MIRROR_METHOD_DISCARD); + if (write_zeroes_ok) { + io_sectors_acct = 0; + } else { + io_sectors_acct = io_sectors; + } break; default: abort(); @@ -424,7 +430,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) sector_num += io_sectors; nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk); if (s->common.speed) { - delay_ns = ratelimit_calculate_delay(&s->limit, io_sectors); + delay_ns = ratelimit_calculate_delay(&s->limit, io_sectors_acct); } } return delay_ns; -- 2.7.4