Message-ID: <40C4319D.6090201@yahoo.com.au>
Date: Mon, 07 Jun 2004 19:13:01 +1000
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: bert hubert <ahu@ds9a.nl>
CC: kernel@kolivas.org, linux-kernel@vger.kernel.org
Subject: Re: BUG in ht-aware scheduler/nice in 2.6.7-rc2 on dual xeon
References: <20040607085625.GA11276@outpost.ds9a.nl>
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bert hubert wrote:

> Fails sometimes, with all processes getting 50%. The above 'screenshot' is
> from the working and expected situation, which happens most of the time.
> 
> When it goes wrong, top shows me that Cpu0 and Cpu1 are 100% user, while
> Cpu2 and Cpu3 are both 100% nice.  The niced processes show up in top as
> PRiority 39, the unniced ones (NI = 0) as PR 25.
> 
> I've also seen it that Cpu2 and Cpu3 are 100% busy, and 0 and 1 are 100%
> nice.
> 

Ahh, that is because we don't do nice-aware SMP balancing. It
is orthogonal to the HT-nice work.

Fixing it properly requires someone to sit down and do some careful
design of nice-aware balancing that should be general enough to handle
the HT problems as a matter of course.
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