From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51352) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cjBo7-00037T-Gu for qemu-devel@nongnu.org; Wed, 01 Mar 2017 16:29:12 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cjBo4-000583-Bg for qemu-devel@nongnu.org; Wed, 01 Mar 2017 16:29:11 -0500 Received: from 1.mo6.mail-out.ovh.net ([46.105.56.136]:60239) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cjBo4-00056n-5W for qemu-devel@nongnu.org; Wed, 01 Mar 2017 16:29:08 -0500 Received: from player761.ha.ovh.net (b9.ovh.net [213.186.33.59]) by mo6.mail-out.ovh.net (Postfix) with ESMTP id 9B48CB43C9 for ; Wed, 1 Mar 2017 22:29:06 +0100 (CET) Date: Wed, 1 Mar 2017 22:29:01 +0100 From: Greg Kurz Message-ID: <20170301222901.6b8154ed@bahia.lan> In-Reply-To: <20170301115026.22621-2-stefanha@redhat.com> References: <20170301115026.22621-1-stefanha@redhat.com> <20170301115026.22621-2-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/G7oOvpA2bE1kf/1J.luz=Kc"; protocol="application/pgp-signature" Subject: Re: [Qemu-devel] [PATCH v3 1/3] qemu-options: explain disk I/O throttling options List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: qemu-devel@nongnu.org, Nini Gu , Alberto Garcia , qemu-block@nongnu.org --Sig_/G7oOvpA2bE1kf/1J.luz=Kc Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 1 Mar 2017 11:50:24 +0000 Stefan Hajnoczi wrote: > The disk I/O throttling options have been listed for a long time but > never explained on the QEMU man page. >=20 > Suggested-by: Nini Gu > Cc: Alberto Garcia > Signed-off-by: Stefan Hajnoczi > --- Reviewed-by: Greg Kurz > qemu-options.hx | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) >=20 > diff --git a/qemu-options.hx b/qemu-options.hx > index c85f77d..bbd1bd9 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -607,6 +607,30 @@ 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 = 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=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 = reads > +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 reque= st > +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 f= or 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 circumventi= ng 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 = disks > +instead of a single larger disk. > @end table > =20 > By default, the @option{cache=3Dwriteback} mode is used. It will report = data --Sig_/G7oOvpA2bE1kf/1J.luz=Kc Content-Type: application/pgp-signature Content-Description: OpenPGP digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAli3PR0ACgkQAvw66wEB28KOGgCfephQ4Duzmd3GC6Q1YISOGvDs uX4AnRYTeSrnK0uJBbkuiXH7p2YbmvU7 =nfzE -----END PGP SIGNATURE----- --Sig_/G7oOvpA2bE1kf/1J.luz=Kc--