diff options
| author | Peter Lieven <pl@kamp.de> | 2014-05-18 00:58:19 +0200 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2014-05-19 13:42:27 +0200 |
| commit | 465bee1da82e43f18d10c43cc7566d0284ad13a9 (patch) | |
| tree | c98c26268e8f10a77bfc39abb72f72f8c7ac9ee8 /block/qapi.c | |
| parent | 82a402e99f3f8c6177528ad6d561bf07ff6ee606 (diff) | |
| download | qemu-465bee1da82e43f18d10c43cc7566d0284ad13a9.tar.gz | |
block: optimize zero writes with bdrv_write_zeroes
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
This significantly speeds up file system initialization and
should speed zero write test used to test backend storage
performance.
I ran the following 2 tests on my internal SSD with a
50G QCOW2 container and on an attached iSCSI storage.
a) mkfs.ext4 -E lazy_itable_init=0,lazy_journal_init=0 /dev/vdX
QCOW2 [off] [on] [unmap]
-----
runtime: 14secs 1.1secs 1.1secs
filesize: 937M 18M 18M
iSCSI [off] [on] [unmap]
----
runtime: 9.3s 0.9s 0.9s
b) dd if=/dev/zero of=/dev/vdX bs=1M oflag=direct
QCOW2 [off] [on] [unmap]
-----
runtime: 246secs 18secs 18secs
filesize: 51G 192K 192K
throughput: 203M/s 2.3G/s 2.3G/s
iSCSI* [off] [on] [unmap]
----
runtime: 8mins 45secs 33secs
throughput: 106M/s 1.2G/s 1.6G/s
allocated: 100% 100% 0%
* The storage was connected via an 1Gbit interface.
It seems to internally handle writing zeroes
via WRITESAME16 very fast.
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block/qapi.c')
| -rw-r--r-- | block/qapi.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/block/qapi.c b/block/qapi.c index af114452e0..75f44f1537 100644 --- a/block/qapi.c +++ b/block/qapi.c @@ -50,6 +50,7 @@ BlockDeviceInfo *bdrv_block_device_info(BlockDriverState *bs) } info->backing_file_depth = bdrv_get_backing_file_depth(bs); + info->detect_zeroes = bs->detect_zeroes; if (bs->io_limits_enabled) { ThrottleConfig cfg; |