linux-kernel - Re: PROBLEM: Unusually high load average when idle in 2.6.35, 2.6.35.1 and later

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Date:	Sat, 2 Oct 2010 23:02:54 -0400
From:	tmhikaru@...il.com
To:	Florian Mickler <florian@...kler.org>,
	linux-kernel@...r.kernel.org, Greg KH <gregkh@...e.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Chase Douglas <chase.douglas@...onical.com>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: PROBLEM: Unusually high load average when idle in 2.6.35, 2.6.35.1 and later

	These final tests I think conclusively prove that I've been on a
wild goose chase. The load average statistic is indeed broken somehow, and I
did bisect it down to where the problem began, however there seems to be no
performance problem related to it I can find. Somehow I must have made a
mistake I didn't catch when I did the original build that led me to believe
on top of the statistic being broken, that it was causing a performance
problem.

	All of the make allnoconfig test results finish within a second of
eachother, with four different kernels tested. I think if there really was a
performance problem it would have reared its head sometime during the
multiple compile tests on different kernels I took. I apologize for wasting
everyones time, especially my own :)

Anyway, the results:

2.6.35.6:
make mrproper && XZ_OPT="" CCACHE_DISABLE="1" time make allnoconfig
5.46user 0.51system 0:07.08elapsed 84%CPU (0avgtext+0avgdata 95888maxresident)k
0inputs+1920outputs (0major+126585minor)pagefaults 0swaps

2.6.35:
make mrproper && XZ_OPT="" CCACHE_DISABLE="1" time make allnoconfig
5.42user 0.50system 0:06.24elapsed 95%CPU (0avgtext+0avgdata 95888maxresident)k
0inputs+1920outputs (0major+126585minor)pagefaults 0swaps

Tim McGrath

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