Re: [PATCH] sched: high-res preemption tick [LWN.net]

From:		Mike Galbraith <efault-AT-gmx.de>
To:		Peter Zijlstra <a.p.zijlstra-AT-chello.nl>
Subject:		Re: [PATCH] sched: high-res preemption tick
Date:		Sat, 13 Oct 2007 09:18:58 +0200
Message-ID:		<1192259938.7369.4.camel@Homer.simpson.net>
Cc:		linux-kernel <linux-kernel-AT-vger.kernel.org>, Ingo Molnar <mingo-AT-elte.hu>, Thomas Gleixner <tglx-AT-linutronix.de>
Archive-link:		Article, Thread

On Fri, 2007-10-12 at 22:51 +0200, Peter Zijlstra wrote:
> Subject: sched: high-res preemption tick
> 
> Use HR-timers (when available) to deliver an accurate preemption tick.

This patch further reduced iperf context switching, and boosted
throughput.

iperf -c localhost -P 10 -t 300

Previously reported numbers

2.6.23-smp
[SUM]  0.0-300.0 sec    153 GBytes  4.39 Gbits/sec
[SUM]  0.0-300.1 sec    148 GBytes  4.23 Gbits/sec
[SUM]  0.0-300.0 sec    152 GBytes  4.36 Gbits/sec

2.6.23-smp-d (sched-devel)
[SUM]  0.0-300.0 sec    173 GBytes  4.96 Gbits/sec
[SUM]  0.0-300.1 sec    173 GBytes  4.96 Gbits/sec
[SUM]  0.0-300.0 sec    172 GBytes  4.93 Gbits/sec

Numbers from fresh pull today

2.6.23-smp-d-hrt
(re-enable PREEMPT_RESTRICT)
[SUM]  0.0-300.1 sec    181 GBytes  5.19 Gbits/sec
[SUM]  0.0-300.0 sec    182 GBytes  5.22 Gbits/sec
[SUM]  0.0-300.1 sec    182 GBytes  5.22 Gbits/sec

2.6.23-smp-d
[SUM]  0.0-300.1 sec    174 GBytes  4.97 Gbits/sec
[SUM]  0.0-300.1 sec    173 GBytes  4.95 Gbits/sec
[SUM]  0.0-300.1 sec    173 GBytes  4.96 Gbits/sec

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