From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60487) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aoT4M-0000b4-F1 for qemu-devel@nongnu.org; Fri, 08 Apr 2016 05:51:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aoT4L-0007d1-Ag for qemu-devel@nongnu.org; Fri, 08 Apr 2016 05:51:14 -0400 MIME-Version: 1.0 In-Reply-To: <20160408101054.14b77747@bahia.huguette.org> References: <20160408101054.14b77747@bahia.huguette.org> Date: Fri, 8 Apr 2016 11:51:05 +0200 Message-ID: From: Pradeep Kiruvale Content-Type: multipart/alternative; boundary=089e01227f4235e158052ff622f2 Subject: Re: [Qemu-devel] Virtio-9p and cgroup io-throttling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Greg Kurz Cc: qemu-devel@nongnu.org, "qemu-discuss@nongnu.org" --089e01227f4235e158052ff622f2 Content-Type: text/plain; charset=UTF-8 Hi Greg, Thanks for your reply. Below is the way how I add to blkio echo "8:16 8388608" > /sys/fs/cgroup/blkio/test/blkio.throttle.write_bps_device The problem I guess is adding these task ids to the "tasks" file in cgroup These threads are started randomly and even then I add the PIDs to the tasks file the cgroup still does not do IO control. Is it possible to reduce these number of threads? I see different number of threads doing IO at different runs. Regards, Pradeep On 8 April 2016 at 10:10, Greg Kurz wrote: > On Thu, 7 Apr 2016 11:48:27 +0200 > Pradeep Kiruvale wrote: > > > Hi All, > > > > I am using virtio-9p for sharing the file between host and guest. To test > > the shared file I do read/write options in the guest.To have controlled > io, > > I am using cgroup blkio. > > > > While using cgroup I am facing two issues,Please find the issues below. > > > > 1. When I do IO throttling using the cgroup the read throttling works > fine > > but the write throttling does not wok. It still bypasses these throttling > > control and does the default, am I missing something here? > > > > Hi, > > Can you provide details on your blkio setup ? > > > I use the following commands to create VM, share the files and to > > read/write from guest. > > > > *Create vm* > > qemu-system-x86_64 -balloon none .......-name vm0 -cpu host -m 128 -smp 1 > > -enable-kvm -parallel .... -fsdev > > local,id=sdb1,path=/mnt/sdb1,security_model=none,writeout=immediate > -device > > virtio-9p-pci,fsdev=sdb1,mount_tag=sdb1 > > > > *Mount file* > > mount -t 9p -o trans=virtio,version=9p2000.L sdb1 /sdb1_ext4 2>>dd.log && > > sync > > > > touch /sdb1_ext4/dddrive > > > > *Write test* > > dd if=/dev/zero of=/sdb1_ext4/dddrive bs=4k count=800000 oflag=direct >> > > dd.log 2>&1 && sync > > > > *Read test* > > dd if=/sdb1_ext4/dddrive of=/dev/null >> dd.log 2>&1 && sync > > > > 2. The other issue is when I run "dd" command inside guest it creates > > multiple threads to write/read. I can see those on host using iotop is > this > > expected behavior? > > > > Yes. QEMU uses a thread pool to handle 9p requests. > > > Regards, > > Pradeep > > Cheers. > > -- > Greg > > --089e01227f4235e158052ff622f2 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hi Greg,

Thanks for your reply.

Below is the way how I add to blkio

<= div>echo "8:16 8388608" > /sys/fs/cgroup/blkio/test/blkio.thro= ttle.write_bps_device

The problem I guess is addin= g these task ids to the "tasks" file in cgroup

These threads are started randomly and even then I add the PIDs to t= he tasks file the cgroup still does not do IO control.

=
Is it possible to reduce these number of threads? I see different numb= er of threads doing IO at different runs.

Regards,=
Pradeep

On 8 April 2016 at 10:10, Greg Kurz <= gkurz@linux.vnet.ibm.com> wrote:
On Thu, 7 Apr 2016 11:48:27 +0200
Pradeep Kiruvale <pradeepki= ruvale@gmail.com> wrote:

> Hi All,
>
> I am using virtio-9p for sharing the file between host and guest. To t= est
> the shared file I do read/write options in the guest.To have controlle= d io,
> I am using cgroup blkio.
>
> While using cgroup I am facing two issues,Please find the issues below= .
>
> 1. When I do IO throttling using the cgroup the read throttling works = fine
> but the write throttling does not wok. It still bypasses these throttl= ing
> control and does the default, am I missing something here?
>

Hi,

Can you provide details on your blkio setup ?

> I use the following commands to create VM, share the files and to
> read/write from guest.
>
> *Create vm*
> qemu-system-x86_64 -balloon none .......-name vm0 -cp= u host -m 128 -smp 1
> -enable-kvm -parallel .... -fsdev
> local,id=3Dsdb1,path=3D/mnt/sdb1,security_model=3Dnone,writeout=3Dimme= diate -device
> virtio-9p-pci,fsdev=3Dsdb1,mount_tag=3Dsdb1
>
> *Mount file*
> mount -t 9p -o trans=3Dvirtio,version=3D9p2000.L sdb1= /sdb1_ext4 2>>dd.log &&
> sync
>
> touch /sdb1_ext4/dddrive
>
> *Write test*
> dd if=3D/dev/zero of=3D/sdb1_ext4/dddrive bs=3D4k cou= nt=3D800000 oflag=3Ddirect >>
> dd.log 2>&1 && sync
>
> *Read test*
> dd if=3D/sdb1_ext4/dddrive of=3D/dev/null >> dd= .log 2>&1 && sync
>
> 2. The other issue is when I run "dd" command inside guest= =C2=A0 it creates
> multiple threads to write/read. I can see those on host using iotop is= this
> expected behavior?
>

Yes. QEMU uses a thread pool to handle 9p requests.

> Regards,
> Pradeep

Cheers.

--
Greg


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