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    SubjectRe: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to 3.6-rc5 on AMD chipsets - bisected
    On Fri, Sep 14, 2012 at 11:40:43PM +0200, Peter Zijlstra wrote:
    > Hmm, cute. What kind of machine did you test it on? Nikolay's machines
    > look to be smallish AMD X6 or ancient Intel c2d (the patch will indeed
    > have absolutely no effect on a dual core).

    Yep, I took an X6 too. So it's a single-socket, 6-core AMD, F10h.

    > I'll see about running pgbench on a bigger Intel tomorrow if Mike
    > doesn't beat me to it.

    Can try that too on one of the bigger machines I have, if needed.

    > 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.
    >
    > Regressing Postgres otoh isn't nice either..
    >
    > Anyway, I guess I'm fine with nixing this patch until we figure out
    > something smarter..
    >
    > I'm also curious to know wth postgres does that this patch makes such a
    > big difference...

    I'm using 9.1 in Debian testing while Nikolay is using 9.2.

    Thanks.

    --
    Regards/Gruss,
    Boris.


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