From nobody Wed Apr 16 07:43:28 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1492768031699480.99598691645576; Fri, 21 Apr 2017 02:47:11 -0700 (PDT) Received: from localhost ([::1]:58251 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d1V9i-0002AB-6i for importer@patchew.org; Fri, 21 Apr 2017 05:47:10 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43263) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d1V68-0007u3-Nx for qemu-devel@nongnu.org; Fri, 21 Apr 2017 05:43:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d1V67-0000Vg-Ka for qemu-devel@nongnu.org; Fri, 21 Apr 2017 05:43:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46274) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d1V67-0000Vb-ER for qemu-devel@nongnu.org; Fri, 21 Apr 2017 05:43:27 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2C41A34157B; Fri, 21 Apr 2017 09:43:26 +0000 (UTC) Received: from localhost (ovpn-116-83.ams2.redhat.com [10.36.116.83]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9DB177EF4E; Fri, 21 Apr 2017 09:43:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 2C41A34157B Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=stefanha@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 2C41A34157B From: Stefan Hajnoczi To: Date: Fri, 21 Apr 2017 10:43:11 +0100 Message-Id: <20170421094316.19361-2-stefanha@redhat.com> In-Reply-To: <20170421094316.19361-1-stefanha@redhat.com> References: <20170421094316.19361-1-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 21 Apr 2017 09:43:26 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL for-2.9 1/6] qemu-options: explain disk I/O throttling options X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Alberto Garcia , Stefan Hajnoczi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Alberto Garcia Reviewed-by: Greg Kurz Message-id: 20170301115026.22621-2-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- qemu-options.hx | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) 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=3D@var{b},bps_rd=3D@var{r},bps_wr=3D@var{w} +Specify bandwidth throttling limits in bytes per second, either for all re= quest +types or for reads or writes only. Small values can lead to timeouts or h= angs +inside the guest. A safe minimum for disks is 2 MB/s. +@item bps_max=3D@var{bm},bps_rd_max=3D@var{rm},bps_wr_max=3D@var{wm} +Specify bursts in bytes per second, either for all request types or for re= ads +or writes only. Bursts allow the guest I/O to spike above the limit +temporarily. +@item iops=3D@var{i},iops_rd=3D@var{r},iops_wr=3D@var{w} +Specify request rate limits in requests per second, either for all request +types or for reads or writes only. +@item iops_max=3D@var{bm},iops_rd_max=3D@var{rm},iops_wr_max=3D@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=3D@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=3D@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 di= sks +instead of a single larger disk. @end table =20 By default, the @option{cache=3Dwriteback} mode is used. It will report da= ta --=20 2.9.3