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[Qemu-devel] [PULL 26/38] block/parallels: optimize linear image expansi
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 26/38] block/parallels: optimize linear image expansion |
Date: |
Fri, 22 May 2015 10:01:58 +0100 |
From: "Denis V. Lunev" <address@hidden>
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>
Signed-off-by: Roman Kagan <address@hidden>
Message-id: address@hidden
CC: Kevin Wolf <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/parallels.c | 42 ++++++++++++++++++++++++++++++++----------
1 file changed, 32 insertions(+), 10 deletions(-)
diff --git a/block/parallels.c b/block/parallels.c
index 440938e..e7124d9 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -88,6 +88,7 @@ typedef struct BDRVParallelsState {
uint32_t *bat_bitmap;
unsigned int bat_size;
+ int64_t data_end;
uint64_t prealloc_size;
ParallelsPreallocMode prealloc_mode;
@@ -187,7 +188,6 @@ static int64_t allocate_cluster(BlockDriverState *bs,
int64_t sector_num)
BDRVParallelsState *s = bs->opaque;
uint32_t idx, offset;
int64_t pos;
- int ret;
idx = sector_num / s->tracks;
offset = sector_num % s->tracks;
@@ -200,14 +200,21 @@ static int64_t allocate_cluster(BlockDriverState *bs,
int64_t sector_num)
}
pos = bdrv_getlength(bs->file) >> BDRV_SECTOR_BITS;
- if (s->prealloc_mode == PRL_PREALLOC_MODE_TRUNCATE) {
- ret = bdrv_truncate(bs->file, (pos + s->tracks) << BDRV_SECTOR_BITS);
- } else {
- ret = bdrv_write_zeroes(bs->file, pos, s->tracks, 0);
- }
- if (ret < 0) {
- return ret;
+ 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);
@@ -549,7 +556,7 @@ 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;
@@ -599,7 +606,11 @@ 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;
@@ -611,6 +622,13 @@ 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;
@@ -685,6 +703,10 @@ 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);
}
--
2.1.0
- [Qemu-devel] [PULL 18/38] block/parallels: move parallels_open/probe to the very end of the file, (continued)
- [Qemu-devel] [PULL 18/38] block/parallels: move parallels_open/probe to the very end of the file, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 16/38] block/parallels: keep BAT bitmap data in little endian in memory, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 15/38] block/parallels: create bat2sect helper, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 19/38] block/parallels: implement parallels_check method of block driver, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 17/38] block/parallels: read parallels image header and BAT into single buffer, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 20/38] block/parallels: implement incorrect close detection, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 21/38] iotests, parallels: check for incorrectly closed image in tests, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 24/38] block/parallels: delay writing to BAT till bdrv_co_flush_to_os, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 22/38] block/parallels: improve image reading performance, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 23/38] block/parallels: create bat_entry_off helper, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 26/38] block/parallels: optimize linear image expansion,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 28/38] configure: handle clang -nopie argument warning, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 27/38] block/parallels: improve image writing performance further, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 29/38] configure: factor out supported flag check, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 25/38] block/parallels: add prealloc-mode and prealloc-size open paramemets, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 30/38] configure: silence glib unknown attribute __alloc_size__, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 31/38] configure: Add workaround for ccache and clang, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 33/38] block: minimal bounce buffer alignment, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 34/38] block: align bounce buffers to page, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 35/38] Revert "block: Fix unaligned zero write", Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 32/38] block: return EPERM on writes or discards to read-only devices, Stefan Hajnoczi, 2015/05/22