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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 /qapi-schema.json | |
parent | 82a402e99f3f8c6177528ad6d561bf07ff6ee606 (diff) | |
download | hqemu-465bee1da82e43f18d10c43cc7566d0284ad13a9.zip hqemu-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 'qapi-schema.json')
-rw-r--r-- | qapi-schema.json | 52 |
1 files changed, 37 insertions, 15 deletions
diff --git a/qapi-schema.json b/qapi-schema.json index 36cb964..70ed7e3 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -942,6 +942,8 @@ # @encryption_key_missing: true if the backing device is encrypted but an # valid encryption key is missing # +# @detect_zeroes: detect and optimize zero writes (Since 2.1) +# # @bps: total throughput limit in bytes per second is specified # # @bps_rd: read throughput limit in bytes per second is specified @@ -977,6 +979,7 @@ 'data': { 'file': 'str', '*node-name': 'str', 'ro': 'bool', 'drv': 'str', '*backing_file': 'str', 'backing_file_depth': 'int', 'encrypted': 'bool', 'encryption_key_missing': 'bool', + 'detect_zeroes': 'BlockdevDetectZeroesOptions', 'bps': 'int', 'bps_rd': 'int', 'bps_wr': 'int', 'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int', 'image': 'ImageInfo', @@ -4255,6 +4258,22 @@ 'data': [ 'ignore', 'unmap' ] } ## +# @BlockdevDetectZeroesOptions +# +# Describes the operation mode for the automatic conversion of plain +# zero writes by the OS to driver specific optimized zero write commands. +# +# @off: Disabled (default) +# @on: Enabled +# @unmap: Enabled and even try to unmap blocks if possible. This requires +# also that @BlockdevDiscardOptions is set to unmap for this device. +# +# Since: 2.1 +## +{ 'enum': 'BlockdevDetectZeroesOptions', + 'data': [ 'off', 'on', 'unmap' ] } + +## # @BlockdevAioOptions # # Selects the AIO backend to handle I/O requests @@ -4306,20 +4325,22 @@ # Options that are available for all block devices, independent of the block # driver. # -# @driver: block driver name -# @id: #optional id by which the new block device can be referred to. -# This is a required option on the top level of blockdev-add, and -# currently not allowed on any other level. -# @node-name: #optional the name of a block driver state node (Since 2.0) -# @discard: #optional discard-related options (default: ignore) -# @cache: #optional cache-related options -# @aio: #optional AIO backend (default: threads) -# @rerror: #optional how to handle read errors on the device -# (default: report) -# @werror: #optional how to handle write errors on the device -# (default: enospc) -# @read-only: #optional whether the block device should be read-only -# (default: false) +# @driver: block driver name +# @id: #optional id by which the new block device can be referred to. +# This is a required option on the top level of blockdev-add, and +# currently not allowed on any other level. +# @node-name: #optional the name of a block driver state node (Since 2.0) +# @discard: #optional discard-related options (default: ignore) +# @cache: #optional cache-related options +# @aio: #optional AIO backend (default: threads) +# @rerror: #optional how to handle read errors on the device +# (default: report) +# @werror: #optional how to handle write errors on the device +# (default: enospc) +# @read-only: #optional whether the block device should be read-only +# (default: false) +# @detect-zeroes: #optional detect and optimize zero writes (Since 2.1) +# (default: off) # # Since: 1.7 ## @@ -4332,7 +4353,8 @@ '*aio': 'BlockdevAioOptions', '*rerror': 'BlockdevOnError', '*werror': 'BlockdevOnError', - '*read-only': 'bool' } } + '*read-only': 'bool', + '*detect-zeroes': 'BlockdevDetectZeroesOptions' } } ## # @BlockdevOptionsFile |