sched: Reduce runqueue lock contention -v6 [LWN.net]

From:		Peter Zijlstra <a.p.zijlstra@chello.nl>
To:		Chris Mason <chris.mason@oracle.com>, Frank Rowand <frank.rowand@am.sony.com>, Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>, Mike Galbraith <efault@gmx.de>, Oleg Nesterov <oleg@redhat.com>, Paul Turner <pjt@google.com>, Jens Axboe <axboe@kernel.dk>, Yong Zhang <yong.zhang0@gmail.com>
Subject:		[PATCH 00/21] sched: Reduce runqueue lock contention -v6
Date:		Tue, 05 Apr 2011 17:23:38 +0200
Message-ID:		<20110405152338.692966333@chello.nl>
Cc:		linux-kernel@vger.kernel.org, Peter Zijlstra <a.p.zijlstra@chello.nl>
Archive-link:		Article, Thread

This patch series aims to optimize remote wakeups by moving most of the
work of the wakeup to the remote cpu and avoid bouncing runqueue data
structures where possible.

As measured by sembench (which basically creates a wakeup storm) on my
dual-socket westmere:

$ for i in /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor ; do echo performance > $i; done
$ echo 4096 32000 64 128 > /proc/sys/kernel/sem
$ ./sembench -t 2048 -w 1900 -o 0

unpatched: run time 30 seconds 647278 worker burns per second
patched:   run time 30 seconds 816715 worker burns per second

I've queued this series for .40.

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