Re: [RFC] Block IO Controller V2 - some results

Corrado Zoccolo
2009-11-23T16:22:06Z

Hi Vivek,
On Mon, Nov 23, 2009 at 4:19 PM, Vivek Goyal <vgoyal@redhat.com> wrote:
> Hi Corrado,
>
> This patch seems to be working much better in marking the random writer
> queue as sync and not interefere with sync-noidle workload.
>
> So frequent migration of random writer queue across group has stopped.
Great. I think this is good regardless of cgroups, to fix the fairness
issue regarding deep aio sync writers against random readers you
reported, so I'll send it to Jens.

> But there seems to be a different issue now after sometime, random writer
> queue stops generating enough traffic and gets deleted after one request
> and root group now runs random reader for sometime. So it basically
> changes the ratio in which random writers and random readers get disk
> share.
>
> I guess part of the dependency comes from kjournald which is in root
> group. But there is something else too because I don't see this happening
> when there are no cgroups. I will do more debugging on this.
Ok.

Thanks,
Corrado

> Thanks
> Vivek
>