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[Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expans
From: |
Denis V. Lunev |
Subject: |
[Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion |
Date: |
Wed, 11 Mar 2015 13:28:20 +0300 |
Plain image expansion spends a lot of time to update image file size.
This seriously affects the performance. The following simple test
qemu_img create -f parallels -o cluster_size=64k ./1.hds 64G
qemu_io -n -c "write -P 0x11 0 1024M" ./1.hds
could be improved if the format driver will pre-allocate some space
in the image file with a reasonable chunk.
This patch preallocates 128 Mb using bdrv_write_zeroes, which should
normally use fallocate() call inside. Fallback to older truncate()
could be used as a fallback using image open options thanks to the
previous patch.
The benefit is around 15%.
Signed-off-by: Denis V. Lunev <address@hidden>
Reviewed-by: Roman Karan <address@hidden>
CC: Kevin Wolf <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
---
block/parallels.c | 36 +++++++++++++++++++++++++++++++++---
1 file changed, 33 insertions(+), 3 deletions(-)
diff --git a/block/parallels.c b/block/parallels.c
index 6f25907..2a1e31f 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -84,6 +84,7 @@ typedef struct BDRVParallelsState {
uint32_t *bat_bitmap;
unsigned int bat_size;
+ int64_t data_end;
uint64_t prealloc_size;
ParallelsPreallocMode prealloc_mode;
@@ -195,7 +196,21 @@ static int64_t allocate_cluster(BlockDriverState *bs,
int64_t sector_num)
}
pos = bdrv_getlength(bs->file) >> BDRV_SECTOR_BITS;
- bdrv_truncate(bs->file, (pos + s->tracks) << BDRV_SECTOR_BITS);
+ if (s->data_end + s->tracks > pos) {
+ int ret;
+ if (s->prealloc_mode == PRL_PREALLOC_MODE_FALLOCATE) {
+ ret = bdrv_write_zeroes(bs->file, s->data_end,
+ s->prealloc_size, 0);
+ } else {
+ ret = bdrv_truncate(bs->file,
+ (s->data_end + s->prealloc_size) << BDRV_SECTOR_BITS);
+ }
+ if (ret < 0) {
+ return ret;
+ }
+ }
+ pos = s->data_end;
+ s->data_end += s->tracks;
s->bat_bitmap[idx] = cpu_to_le32(pos / s->off_multiplier);
@@ -539,7 +554,7 @@ static int parallels_open(BlockDriverState *bs, QDict
*options, int flags,
{
BDRVParallelsState *s = bs->opaque;
ParallelsHeader ph;
- int ret, size;
+ int ret, size, i;
QemuOpts *opts = NULL;
Error *local_err = NULL;
char *buf;
@@ -589,7 +604,11 @@ static int parallels_open(BlockDriverState *bs, QDict
*options, int flags,
ret = -ENOMEM;
goto fail;
}
- if (le32_to_cpu(ph.data_off) < s->header_size) {
+ s->data_end = le32_to_cpu(ph.data_off);
+ if (s->data_end == 0) {
+ s->data_end = ROUND_UP(bat_entry_off(s->bat_size), BDRV_SECTOR_SIZE);
+ }
+ if (s->data_end < s->header_size) {
/* there is not enough unused space to fit to block align between BAT
and actual data. We can't avoid read-modify-write... */
s->header_size = size;
@@ -601,6 +620,13 @@ static int parallels_open(BlockDriverState *bs, QDict
*options, int flags,
}
s->bat_bitmap = (uint32_t *)(s->header + 1);
+ for (i = 0; i < s->bat_size; i++) {
+ int64_t off = bat2sect(s, i);
+ if (off >= s->data_end) {
+ s->data_end = off + s->tracks;
+ }
+ }
+
if (le32_to_cpu(ph.inuse) == HEADER_INUSE_MAGIC) {
/* Image was not closed correctly. The check is mandatory */
s->header_unclean = true;
@@ -671,6 +697,10 @@ static void parallels_close(BlockDriverState *bs)
parallels_update_header(bs);
}
+ if (bs->open_flags & BDRV_O_RDWR) {
+ bdrv_truncate(bs->file, s->data_end << BDRV_SECTOR_BITS);
+ }
+
g_free(s->bat_dirty_bmap);
qemu_vfree(s->header);
}
--
1.9.1
- [Qemu-devel] [PATCH 12/27] parallels: change copyright information in the image header, (continued)
- [Qemu-devel] [PATCH 12/27] parallels: change copyright information in the image header, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 04/27] block/parallels: read up to cluster end in one go, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 14/27] block/parallels: create bat2sect helper, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 07/27] block/parallels: replace magic constants 4, 64 with proper sizeofs, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 09/27] iotests, parallels: test for write into Parallels image, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 25/27] block/parallels: add prealloc-mode and prealloc-size open paramemets, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 17/27] block/parallels: move parallels_open/probe to the very end of the file, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 02/27] block/parallels: rename parallels_header to ParallelsHeader, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 23/27] block/parallels: create bat_entry_off helper, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 06/27] block/parallels: provide _co_readv routine for parallels format driver, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion,
Denis V. Lunev <=
- [Qemu-devel] [PATCH 16/27] block/parallels: read parallels image header and BAT into single buffer, Denis V. Lunev, 2015/03/11
- [Qemu-devel] [PATCH 20/27] iotests, parallels: check for incorrectly closed image in tests, Denis V. Lunev, 2015/03/11