18 Feb
2011
18 Feb
'11
10:08 a.m.
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