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[Qemu-devel] [PATCH 19/19] block/parallels: optimize linear image expans
From: |
Denis V. Lunev |
Subject: |
[Qemu-devel] [PATCH 19/19] block/parallels: optimize linear image expansion |
Date: |
Tue, 30 Dec 2014 13:07:12 +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%.
This patch is final in this series. Block driver has near native
performance now.
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Kevin Wolf <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
---
block/parallels.c | 35 +++++++++++++++++++++++++++++++++--
1 file changed, 33 insertions(+), 2 deletions(-)
diff --git a/block/parallels.c b/block/parallels.c
index 12a9cea..5ec4a0d 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -82,6 +82,7 @@ typedef struct BDRVParallelsState {
int bat_cache_off;
int data_off;
+ int64_t prealloc_off;
uint64_t prealloc_size;
ParallelsPreallocMode prealloc_mode;
@@ -216,9 +217,19 @@ static int parallels_open(BlockDriverState *bs, QDict
*options, int flags,
goto fail_options;
}
- for (i = 0; i < s->bat_size; i++)
+ for (i = 0; i < s->bat_size; i++) {
+ int64_t off;
le32_to_cpus(&s->bat[i]);
+ if (s->bat[i] == 0) {
+ continue;
+ }
+ off = s->bat[i] * s->off_multiplier;
+ if (off >= s->prealloc_off) {
+ s->prealloc_off = off + s->tracks;
+ }
+ }
+
qemu_co_mutex_init(&s->lock);
s->bat_cache_off = -1;
@@ -230,6 +241,9 @@ static int parallels_open(BlockDriverState *bs, QDict
*options, int flags,
if (s->data_off == 0) {
s->data_off = ROUND_UP(bat_offset(s->bat_size), BDRV_SECTOR_SIZE);
}
+ if (s->prealloc_off == 0) {
+ s->prealloc_off = s->data_off >> BDRV_SECTOR_BITS;
+ }
return 0;
@@ -338,7 +352,19 @@ static int64_t allocate_sector(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->prealloc_off + s->tracks > pos) {
+ if (s->prealloc_mode == PRL_PREALLOC_MODE_FALLOCATE)
+ ret = bdrv_write_zeroes(bs->file, s->prealloc_off,
+ s->prealloc_size, 0);
+ else
+ ret = bdrv_truncate(bs->file,
+ (s->prealloc_off + s->prealloc_size) << BDRV_SECTOR_BITS);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+ pos = s->prealloc_off;
+ s->prealloc_off += s->tracks;
ret = cache_bat(bs, idx, pos / s->off_multiplier);
if (ret < 0) {
@@ -546,6 +572,11 @@ exit:
static void parallels_close(BlockDriverState *bs)
{
BDRVParallelsState *s = bs->opaque;
+
+ if (bs->open_flags & BDRV_O_RDWR) {
+ bdrv_truncate(bs->file, s->prealloc_off << BDRV_SECTOR_BITS);
+ }
+
qemu_vfree(s->bat_cache);
g_free(s->bat);
}
--
1.9.1
- [Qemu-devel] [PATCH 09/19] iotests, parallels: test for write into Parallels image, (continued)
- [Qemu-devel] [PATCH 09/19] iotests, parallels: test for write into Parallels image, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 10/19] block/parallels: support parallels image creation, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 13/19] block/parallels: store ParallelsHeader to the BDRVParallelsState, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 11/19] iotests, parallels: test for newly created parallels image via qemu-img, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 16/19] block/parallels: no need to flush on each block allocation table update, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 15/19] block/parallels: rename catalog_ names to bat_, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 12/19] parallels: change copyright information in the image header, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 17/19] block/parallels: delay writing to BAT till bdrv_co_flush_to_os, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 14/19] block/parallels: create catalog_offset helper, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 18/19] block/parallels: add prealloc-mode and prealloc-size open paramemets, Denis V. Lunev, 2014/12/30
- [Qemu-devel] [PATCH 19/19] block/parallels: optimize linear image expansion,
Denis V. Lunev <=