From c92607520eb1b5fad188e11c3602f700439895f2 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 21 Jul 2010 10:04:03 -0300 Subject: [PATCH 19/24] block: Change bdrv_commit to handle multiple sectors at once RH-Author: Kevin Wolf Message-id: <1279706643-10383-1-git-send-email-kwolf@redhat.com> Patchwork-id: 10870 O-Subject: [RHEL-6 qemu-kvm PATCH] block: Change bdrv_commit to handle multiple sectors at once Bugzilla: 615152 RH-Acked-by: Alex Williamson RH-Acked-by: Jes Sorensen RH-Acked-by: Christoph Hellwig Bugzilla: 615152 Upstream status: Submitted bdrv_commit copies the image to its backing file sector by sector, which is (surprise!) relatively slow. Let's take a larger buffer and handle more sectors at once if possible. With a 1G qcow2 file, this brought the time bdrv_commit takes down from 5:06 min to 1:14 min for me. Signed-off-by: Kevin Wolf --- block.c | 39 ++++++++++++++++++++------------------- 1 files changed, 20 insertions(+), 19 deletions(-) Signed-off-by: Eduardo Habkost --- block.c | 39 ++++++++++++++++++++------------------- 1 files changed, 20 insertions(+), 19 deletions(-) diff --git a/block.c b/block.c index d250c0d..8abe538 100644 --- a/block.c +++ b/block.c @@ -677,14 +677,16 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res) return bs->drv->bdrv_check(bs, res); } +#define COMMIT_BUF_SECTORS 2048 + /* commit COW file into the raw image */ int bdrv_commit(BlockDriverState *bs) { BlockDriver *drv = bs->drv; - int64_t i, total_sectors; - int n, j, ro, open_flags; + int64_t sector, total_sectors; + int n, ro, open_flags; int ret = 0, rw_ret = 0; - unsigned char sector[512]; + uint8_t *buf; char filename[1024]; BlockDriverState *bs_rw, *bs_ro; @@ -727,22 +729,20 @@ int bdrv_commit(BlockDriverState *bs) } total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; - for (i = 0; i < total_sectors;) { - if (drv->bdrv_is_allocated(bs, i, 65536, &n)) { - for(j = 0; j < n; j++) { - if (bdrv_read(bs, i, sector, 1) != 0) { - ret = -EIO; - goto ro_cleanup; - } + buf = qemu_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); - if (bdrv_write(bs->backing_hd, i, sector, 1) != 0) { - ret = -EIO; - goto ro_cleanup; - } - i++; - } - } else { - i += n; + for (sector = 0; sector < total_sectors; sector += n) { + if (drv->bdrv_is_allocated(bs, sector, COMMIT_BUF_SECTORS, &n)) { + + if (bdrv_read(bs, sector, buf, n) != 0) { + ret = -EIO; + goto ro_cleanup; + } + + if (bdrv_write(bs->backing_hd, sector, buf, n) != 0) { + ret = -EIO; + goto ro_cleanup; + } } } @@ -759,6 +759,7 @@ int bdrv_commit(BlockDriverState *bs) bdrv_flush(bs->backing_hd); ro_cleanup: + qemu_free(buf); if (ro) { /* re-open as RO */ -- 1.7.0.3