Re: [patch v7 0/21] sched: power aware scheduling

From: Ingo Molnar
Date: Tue Apr 30 2013 - 04:41:47 EST



* Mike Galbraith <bitbucket@xxxxxxxxx> wrote:

> On Tue, 2013-04-30 at 07:16 +0200, Mike Galbraith wrote:
>
> > Well now, that's not exactly what I expected to see for AIM7 compute.
> > Filesystem is munching cycles otherwise used for compute when load is
> > spread across the whole box vs consolidated.
>
> So AIM7 compute performance delta boils down to: powersaving stacks
> tasks, so they pat single bit of spinning rust sequentially/gently.

So AIM7 with real block IO improved, due to sequentiality. Does it improve
if AIM7 works on an SSD, or into ramdisk?

Which are the workloads where 'powersaving' mode hurts workload
performance measurably?

Thanks,

Ingo
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