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 <kw...@redhat.com>
---
block.c | 35 ++++++++++++++++++-----------------
1 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/block.c b/block.c
index 65cf4dc..12dbc43 100644
--- a/block.c
+++ b/block.c
@@ -729,9 +729,9 @@ int bdrv_commit(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
int64_t i, total_sectors;
- int n, j, ro, open_flags;
+ int n, ro, open_flags;
int ret = 0, rw_ret = 0;
- unsigned char sector[BDRV_SECTOR_SIZE];
+ uint8_t *buf;
char filename[1024];
BlockDriverState *bs_rw, *bs_ro;
@@ -774,25 +774,26 @@ int bdrv_commit(BlockDriverState *bs)
}
total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+ buf = qemu_malloc(2048 * BDRV_SECTOR_SIZE);
+
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;
- }
+ if (drv->bdrv_is_allocated(bs, i, 2048, &n)) {
- if (bdrv_write(bs->backing_hd, i, sector, 1) != 0) {
- ret = -EIO;
- goto ro_cleanup;
- }
- i++;
- }
- } else {
- i += n;
+ if (bdrv_read(bs, i, buf, n) != 0) {
+ ret = -EIO;
+ goto ro_cleanup;
+ }
+
+ if (bdrv_write(bs->backing_hd, i, buf, n) != 0) {
+ ret = -EIO;
+ goto ro_cleanup;
+ }
}
+ i += n;
}
+ qemu_free(buf);
+
if (drv->bdrv_make_empty) {
ret = drv->bdrv_make_empty(bs);
bdrv_flush(bs);
--
1.7.1.1
