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 <gk...@linux.vnet.ibm.com> wrote: > On Thu, 7 Apr 2016 11:48:27 +0200 > Pradeep Kiruvale <pradeepkiruv...@gmail.com> 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 > >