mirrors/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

block/parallels: delay writing to BAT till bdrv_co_flush_to_os

Browse Source 
The idea is that we do not need to immediately sync BAT to the image as
from the guest point of view there is a possibility that IO is lost
even in the physical controller until flush command was finished.
bdrv_co_flush_to_os is exactly the right place for this purpose.

Technically the patch uses loaded BAT data as a cache and performs
actual on-disk metadata updates in parallels_co_flush_to_os callback.

This patch speed ups
  qemu-img create -f parallels -o cluster_size=64k ./1.hds 64G
  qemu-io -f parallels -c "write -P 0x11 0 1024k" 1.hds
writing from 50-60 Mb/sec to 80-90 Mb/sec on rotational media and
from 160 Mb/sec to 190 Mb/sec on SSD disk.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Roman Kagan <rkagan@parallels.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Roman Kagan <rkagan@parallels.com>
Message-id: 1430207220-24458-25-git-send-email-den@openvz.org
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Denis V. Lunev 2015-04-28 10:46:57 +03:00 committed by Stefan Hajnoczi
parent 2d68e22e94
commit 0d31c7c200
1 changed files with 44 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
block/parallels.c
View File

@ -30,6 +30,7 @@
#include "qemu-common.h"
#include "block/block_int.h"
#include "qemu/module.h"
#include "qemu/bitmap.h"
/**************************************************************/
@ -66,6 +67,9 @@ typedef struct BDRVParallelsState {
uint32_t header_size;
bool header_unclean;
unsigned long *bat_dirty_bmap;
unsigned int bat_dirty_block;
uint32_t *bat_bitmap;
unsigned int bat_size;
@ -165,15 +169,43 @@ static int64_t allocate_cluster(BlockDriverState *bs, int64_t sector_num)
}
s->bat_bitmap[idx] = cpu_to_le32(pos / s->off_multiplier);
ret = bdrv_pwrite(bs->file, bat_entry_off(idx), s->bat_bitmap + idx,
sizeof(s->bat_bitmap[idx]));
if (ret < 0) {
s->bat_bitmap[idx] = 0;
return ret;
}
bitmap_set(s->bat_dirty_bmap, bat_entry_off(idx) / s->bat_dirty_block, 1);
return bat2sect(s, idx) + offset;
}
static coroutine_fn int parallels_co_flush_to_os(BlockDriverState *bs)
{
BDRVParallelsState *s = bs->opaque;
unsigned long size = DIV_ROUND_UP(s->header_size, s->bat_dirty_block);
unsigned long bit;
qemu_co_mutex_lock(&s->lock);
bit = find_first_bit(s->bat_dirty_bmap, size);
while (bit < size) {
uint32_t off = bit * s->bat_dirty_block;
uint32_t to_write = s->bat_dirty_block;
int ret;
if (off + to_write > s->header_size) {
to_write = s->header_size - off;
}
ret = bdrv_pwrite(bs->file, off, (uint8_t *)s->header + off, to_write);
if (ret < 0) {
qemu_co_mutex_unlock(&s->lock);
return ret;
}
bit = find_next_bit(s->bat_dirty_bmap, size, bit + 1);
}
bitmap_zero(s->bat_dirty_bmap, size);
qemu_co_mutex_unlock(&s->lock);
return 0;
}
static int64_t coroutine_fn parallels_co_get_block_status(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, int *pnum)
{
@ -557,6 +589,10 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
}
}
s->bat_dirty_block = 4 * getpagesize();
s->bat_dirty_bmap =
bitmap_new(DIV_ROUND_UP(s->header_size, s->bat_dirty_block));
qemu_co_mutex_init(&s->lock);
return 0;
@ -578,6 +614,7 @@ static void parallels_close(BlockDriverState *bs)
parallels_update_header(bs);
}
g_free(s->bat_dirty_bmap);
qemu_vfree(s->header);
}
@ -608,6 +645,7 @@ static BlockDriver bdrv_parallels = {
.bdrv_close = parallels_close,
.bdrv_co_get_block_status = parallels_co_get_block_status,
.bdrv_has_zero_init = bdrv_has_zero_init_1,
.bdrv_co_flush_to_os = parallels_co_flush_to_os,
.bdrv_co_readv = parallels_co_readv,
.bdrv_co_writev = parallels_co_writev,