Re: [PATCH 5/7] perf: Optimise topology iteration

From: Andi Kleen
Date: Mon Jan 03 2011 - 10:20:32 EST


On Mon, Jan 03, 2011 at 12:02:10PM +0100, Peter Zijlstra wrote:
> On Mon, 2010-12-27 at 23:38 +0800, Lin Ming wrote:
> > Currently we iterate the full machine looking for a matching core_id/nb
> > for the percore and the amd northbridge stuff , using a smaller topology
> > mask makes sense.
>
> Does topology_thread_cpumask() include offline cpus? I tried looking at
> it, but I cannot find any code clearing bits in that mask on offline.

The problem is not only at offline, but also at online between CPUs
going online. I don't think the patch is a good idea and it doesn't
even have any advantages either since this is a initialization only
slow path.

-Andi
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