Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to3.6-rc5 on AMD chipsets - bisected

From: Linus Torvalds
Date: Fri Sep 14 2012 - 17:45:08 EST

On Fri, Sep 14, 2012 at 2:40 PM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> The problem the patch is trying to address is not having to scan an
> entire package for idle cores on every wakeup now that packages are
> getting stupid big.

No, it does something *else* too. That whole "left-right" logic to
(according to the commit message) "prevent bouncing" is entirely new,

So it is *not* just about avoiding to have to scan the whole package.
It changes actual semantics too. No?

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