Re: [patch] CFS scheduler, v3

From: Christoph Lameter
Date: Tue Apr 24 2007 - 13:48:03 EST

On Tue, 24 Apr 2007, Siddha, Suresh B wrote:

> > .5% is usually in the noise ratio. Are you consistently seeing an
> > improvement or is that sporadic?
> No. This is consistent. I am waiting for the perf data on a much much bigger
> NUMA box.
> Anyhow, this is a straight forward optimization and needs to be done. Do you
> have any specific concerns?

Yes there should not be contention on per cpu data in principle. The
point of per cpu data is for the cpu to have access to contention free

If the data is contented then it should be moved out of per cpu data and properly
placed to minimize contention. Otherwise we will get into cacheline
aliases (__read_mostly in per cpu??) etc etc in the per cpu areas.

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