From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35988) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cfrCA-00043U-QU for qemu-devel@nongnu.org; Mon, 20 Feb 2017 11:52:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cfrC9-0002j3-RR for qemu-devel@nongnu.org; Mon, 20 Feb 2017 11:52:14 -0500 From: Stefan Hajnoczi Date: Mon, 20 Feb 2017 16:52:04 +0000 Message-Id: <20170220165204.1980-1-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH] qemu-options: explain disk I/O throttling options List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Nini Gu , qemu-block@nongnu.org, Alberto Garcia , Stefan Hajnoczi 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 Cc: Alberto Garcia Signed-off-by: Stefan Hajnoczi --- 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