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| author | Stefan Hajnoczi <stefanha@redhat.com> | 2017-03-01 11:50:24 +0000 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2017-04-21 10:36:12 +0100 |
| commit | 01f9cfab8bf73653ff6df066155a01ce7892cf7d (patch) | |
| tree | 7ee866ed04fa120b051b60b5b08dc4db503b7180 /qemu-options.hx | |
| parent | fa54abb8c298f892639ffc4bc2f61448ac3be4a1 (diff) | |
| download | qemu-01f9cfab8bf73653ff6df066155a01ce7892cf7d.zip qemu-01f9cfab8bf73653ff6df066155a01ce7892cf7d.tar.gz qemu-01f9cfab8bf73653ff6df066155a01ce7892cf7d.tar.bz2 | |
qemu-options: explain disk I/O throttling options
The disk I/O throttling options have been listed for a long time but
never explained on the QEMU man page.
Suggested-by: Nini Gu <ngu@redhat.com>
Cc: Alberto Garcia <berto@igalia.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-id: 20170301115026.22621-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'qemu-options.hx')
| -rw-r--r-- | qemu-options.hx | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/qemu-options.hx b/qemu-options.hx index 99af8ed..9171bd5 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -635,6 +635,30 @@ file sectors into the image file. conversion of plain zero writes by the OS to driver specific optimized zero write commands. You may even choose "unmap" if @var{discard} is set to "unmap" to allow a zero write to be converted to an UNMAP operation. +@item bps=@var{b},bps_rd=@var{r},bps_wr=@var{w} +Specify bandwidth throttling limits in bytes per second, either for all request +types or for reads or writes only. Small values can lead to timeouts or hangs +inside the guest. A safe minimum for disks is 2 MB/s. +@item bps_max=@var{bm},bps_rd_max=@var{rm},bps_wr_max=@var{wm} +Specify bursts in bytes per second, either for all request types or for reads +or writes only. Bursts allow the guest I/O to spike above the limit +temporarily. +@item iops=@var{i},iops_rd=@var{r},iops_wr=@var{w} +Specify request rate limits in requests per second, either for all request +types or for reads or writes only. +@item iops_max=@var{bm},iops_rd_max=@var{rm},iops_wr_max=@var{wm} +Specify bursts in requests per second, either for all request types or for reads +or writes only. Bursts allow the guest I/O to spike above the limit +temporarily. +@item iops_size=@var{is} +Let every @var{is} bytes of a request count as a new request for iops +throttling purposes. Use this option to prevent guests from circumventing iops +limits by sending fewer but larger requests. +@item group=@var{g} +Join a throttling quota group with given name @var{g}. All drives that are +members of the same group are accounted for together. Use this option to +prevent guests from circumventing throttling limits by using many small disks +instead of a single larger disk. @end table By default, the @option{cache=writeback} mode is used. It will report data |