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 <n...@redhat.com>
Cc: Alberto Garcia <be...@igalia.com>
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
qemu-options.hx | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/qemu-options.hx b/qemu-options.hx
index 5633d39..b2254cc 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -587,6 +587,31 @@ 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. Values must be larger than the maximum
+request size to avoid timeouts or hangs in the guest. At minimum use 2 MB/s
+for disks.
+@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. The default burst value is 1/10th of the limit.
+@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 bps_max=@var{bm},bps_rd_max=@var{rm},bps_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. The default burst value is 1/10th of the limit.
+@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
--
2.9.3
