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

[Linus Torvalds]

On Mon, Sep 24, 2012 at 7:49 PM, Mike Galbraith <efault@xxxxxx> wrote:
>
> Ah.  That's what I did to select_idle_sibling() in a nutshell, converted
> the problematic large L3 packages into multiple ~core2duo pairs, modulo
> shared L2 'course.  Bounce proof, and on Westmere, the jabbering back
> and forth in L3 somehow doesn't hurt as much as expected, so the things
> act (more or less, L2 traffic _does_ matter;) like the real deal.

Right. But your patch *only* looked at the pair.

Which may be bounce-proof, but we also saw that it was unacceptable.

              Linus
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