Re: [libvirt] [PATCH 0/6 v3] Add blkio cgroup support

[Dominik Klein <dk in-telegence net>]

>> As far as I understand, and as far as I saw during my tests, the blkio
>> controller only works for sync I/O requests (eg dd with oflag=direct).
>> Buffered I/O is not part of the control.
> 
> Yes, you are right.

whew :)

>> And since a VM's I/O is most likely buffered in some fashion, this does
>> not have any effect. That's what my tests showed.
> 
> how about the start Guest with option "cache=none" to bypass pagecache?
> This should help i think.

I will read up on where to set that and give it a try. Thanks for the hint.

>>
>> Did your tests show something different? Maybe I did things wrong then.
> 
> I think blkio cgroup should work if "cache=none" is set. But I didn't try it,
> Will try it later.

Please let us know what you found out during your tests.

Regards
Dominik