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Subject: Re: [tip:sched/urgent] sched: Fix select_idle_sibling() regression
 in selecting an idle SMT sibling
From: "Alex,Shi" <alex.shi@intel.com>
To: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
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Date: Thu, 22 Dec 2011 09:31:42 +0800
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> > > Even with this fix, the loopback netperf testing TCP-RR, still have
> > > about 5% regresion on our 2 socket * 8 cores SNB machine.
> > > which is your patchset includes all cleaning? wondering if that is helpful.
> > 
> > Sorry, but that question fails to parse here. What were you asking?

This patch partly fixed a performance regression that triggered by
4dcfe1025b513c2c, but issue still exists.
> 
> Yes Alex. You need to elaborate your question. Regression to what kernel
> etc?
> 
> Also there is another known issue that's been addressed in -tip. Here is
> that patch. https://lkml.org/lkml/2011/12/21/137

Thanks! 
I am testing whole tip changes against 3.2-rc6. On the 4dcfe1025b513c2c
commit, seems interrupts is abnormal. So maybe above fix is suit for
this issue. wait the results.