libvirt users - Feb 2011 - Question about putting vm in blkio cgroup

Hello,

I have another question about cgroup in libvirt
I create a script that put vm in cgroup for limiting blkio

sudo cgcreate -f 750 -d 750 -a $user:$group -g blkio:$alias
pid=`pgrep $alias`
echo $pid > /dev/cgroup/blkio/$alias/tasks
$virsh schedinfo --set cpu_shares=$cpu $alias
echo "8:0 $disk_io" >
/dev/cgroup/blkio/$alias/blkio.throttle.read_bps_device
echo "8:0 $disk_io" >
/dev/cgroup/blkio/$alias/blkio.throttle.write_bps_device

For example I write:
8:0	10485760 to /dev/cgroup/blkio/$alias/blkio.throttle.*_bps_device
So there should be limit to 10Mbyte/s to acces to /dev/sda

But when I run hdparm -t /dev/vda or dd to test limits I receive value
~ 70 Mbyte/s


-- 
Nikita A Menkovich
JID: menkovich at gmail.com