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

[Linus Torvalds]

On Thu, Sep 27, 2012 at 10:45 AM,  <david@xxxxxxx> wrote:
>
> For the initial starup of a new process, finding as idle and remote a core
> to start on (minimum sharing with existing processes) is probably the smart
> thing to do.

Actually, no.

It's *exec* that should go remote. New processes (fork, vfork or
clone) absolutely should *not* go remote at all.

vfork() should stay on the same CPU (synchronous wakeup), fork()
should possibly go SMT (likely exec in the near future will spread it
out), and clone should likely just stay close too.

           Linus
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