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 /qmp-commands.hx | |
| parent | 82a402e99f3f8c6177528ad6d561bf07ff6ee606 (diff) | |
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 'qmp-commands.hx')
| -rw-r--r-- | qmp-commands.hx | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/qmp-commands.hx b/qmp-commands.hx index cae890ee5d..2c53c1ba2e 100644 --- a/qmp-commands.hx +++ b/qmp-commands.hx @@ -2032,6 +2032,8 @@ Each json-object contain the following: - "iops_rd_max": read I/O operations max (json-int) - "iops_wr_max": write I/O operations max (json-int) - "iops_size": I/O size when limiting by iops (json-int) + - "detect_zeroes": detect and optimize zero writing (json-string) + - Possible values: "off", "on", "unmap" - "image": the detail of the image, it is a json-object containing the following: - "filename": image file name (json-string) @@ -2108,6 +2110,7 @@ Example: "iops_rd_max": 0, "iops_wr_max": 0, "iops_size": 0, + "detect_zeroes": "on", "image":{ "filename":"disks/test.qcow2", "format":"qcow2", |