From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54494) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aviWA-0000YC-IJ for qemu-devel@nongnu.org; Thu, 28 Apr 2016 05:46:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aviW6-0006Rq-DI for qemu-devel@nongnu.org; Thu, 28 Apr 2016 05:45:54 -0400 MIME-Version: 1.0 In-Reply-To: <20160427191215.037c4c5c@bahia.huguette.org> References: <20160427083840.GA27160@igalia.com> <20160427191215.037c4c5c@bahia.huguette.org> Date: Thu, 28 Apr 2016 11:45:41 +0200 Message-ID: From: Pradeep Kiruvale Content-Type: multipart/alternative; boundary=001a11425326b392e805318863a4 Subject: Re: [Qemu-devel] [Qemu-discuss] iolimits for virtio-9p List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: Alberto Garcia , qemu-devel@nongnu.org, "qemu-discuss@nongnu.org" --001a11425326b392e805318863a4 Content-Type: text/plain; charset=UTF-8 On 27 April 2016 at 19:12, Greg Kurz wrote: > On Wed, 27 Apr 2016 16:39:58 +0200 > Pradeep Kiruvale wrote: > > > On 27 April 2016 at 10:38, Alberto Garcia wrote: > > > > > On Wed, Apr 27, 2016 at 09:29:02AM +0200, Pradeep Kiruvale wrote: > > > > > > > Thanks for the reply. I am still in the early phase, I will let you > > > > know if any changes are needed for the APIs. > > > > > > > > We might also have to implement throttle-group.c for 9p devices, if > > > > we want to apply throttle for group of devices. > > > > > > Fair enough, but again please note that: > > > > > > - throttle-group.c is not meant to be generic, but it's tied to > > > BlockDriverState / BlockBackend. > > > - it is currently being rewritten: > > > https://lists.gnu.org/archive/html/qemu-block/2016-04/msg00645.html > > > > > > If you can explain your use case with a bit more detail we can try to > > > see what can be done about it. > > > > > > > > We want to use virtio-9p for block io instead of virtio-blk-pci. But in > > case of > > 9p is mostly aimed at sharing files... why would you want to use it for > block io instead of a true block device ? And how would you do that ? > *Yes, we want to share the files itself. So we are using the virtio-9p.* *We want to have QoS on these files access for every VM.* > > > virtio-9p we can just use fsdev devices, so we want to apply throttling > > (QoS) > > on these devices and as of now the io throttling only possible with the > > -drive option. > > > > Indeed. > > > As a work around we are doing the throttling using cgroup. It has its own > > costs. > > Can you elaborate ? > *We saw that we need to create cgroups and set it and also we observed lot of iowaits * *compared to implementing the throttling inside the qemu.* *This we did observe by using the virtio-blk-pci devices. (Using cgroups Vs qemu throttling)* Thanks, Pradeep --001a11425326b392e805318863a4 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On 27 April 2016 at 19:12, Greg Kurz <gkurz@linux.vnet.ibm.com<= /a>> wrote:
On= Wed, 27 Apr 2016 16:39:58 +0200
Pradeep Kiruvale <pradeepki= ruvale@gmail.com> wrote:

> On 27 April 2016 at 10:38, Alberto Garcia <berto@igalia.com> wrote:
>
> > On Wed, Apr 27, 2016 at 09:29:02AM +0200, Pradeep Kiruvale wrote:=
> >
> > > Thanks for the reply. I am still in the early phase, I will = let you
> > > know if any changes are needed for the APIs.
> > >
> > > We might also have to implement throttle-group.c for 9p devi= ces, if
> > > we want to apply throttle for group of devices.
> >
> > Fair enough, but again please note that:
> >
> > - throttle-group.c is not meant to be generic, but it's tied = to
> >=C2=A0 =C2=A0BlockDriverState / BlockBackend.
> > - it is currently being rewritten:
> >=C2=A0 =C2=A0https://lis= ts.gnu.org/archive/html/qemu-block/2016-04/msg00645.html
> >
> > If you can explain your use case with a bit more detail we can tr= y to
> > see what can be done about it.
> >
> >
> We want to use=C2=A0 virtio-9p for block io instead of virtio-blk-pci.= But in
> case of

9p is mostly aimed at sharing files... why would you want to use it = for
block io instead of a true block device ? And how would you do that ?

Yes, we want to share the files itself. S= o we are using the virtio-9p.
We want to have QoS on these= files access for every VM.
=C2=A0

> virtio-9p we can just use fsdev devices, so we want to apply throttlin= g
> (QoS)
> on these devices and as of now the io throttling only possible with th= e
> -drive option.
>

Indeed.

> As a work around we are doing the throttling using cgroup. It has its = own
> costs.

Can you elaborate ?

We= saw that we need to create cgroups and set it and also we observed lot of = iowaits=C2=A0
compared to implementing the throttling insi= de the qemu.
This we did observe by using the virtio-blk-p= ci devices. (Using cgroups Vs qemu throttling)
=C2=A0

Thanks,
Pradeep
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