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Date: Fri, 28 Sep 2012 14:30:09 +0200
From: Borislav Petkov <bp@alien8.de>
To: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: 20% performance drop on PostgreSQL 9.2 from kernel 3.5.3 to
 3.6-rc5 on AMD chipsets - bisected
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On Fri, Sep 28, 2012 at 05:50:20AM +0200, Mike Galbraith wrote:
> And wakeup preemption is still disabled as well, correct?

Yes it is by default anyway:

$ cat /mnt/dbg/sched_features
GENTLE_FAIR_SLEEPERS START_DEBIT NO_NEXT_BUDDY LAST_BUDDY CACHE_HOT_BUDDY NO_WAKEUP_PREEMPTION ARCH_POWER NO_HRTICK NO_DOUBLE_TICK LB_BIAS OWNER_SPIN NONTASK_POWER TTWU_QUEUE NO_FORCE_SD_OVERLAP RT_RUNTIME_SHARE NO_LB_MIN

NO_WAKEUP_PREEMPTION brings 9% improvement with pgbench, btw:

http://marc.info/?l=linux-kernel&m=134876312310048

-- 
Regards/Gruss,
Boris.