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Message-ID: <20071030072658.GB20372@elte.hu>
Date: Tue, 30 Oct 2007 08:26:58 +0100
From: Ingo Molnar <mingo@...e.hu>
To: "Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: aim7 -30% regression in 2.6.24-rc1
* Zhang, Yanmin <yanmin_zhang@...ux.intel.com> wrote:
> sub-bisecting captured patch
> 38ad464d410dadceda1563f36bdb0be7fe4c8938(sched: uniform tunings)
> caused 20% regression of aim7.
>
> The last 10% should be also related to sched parameters, such like
> sysctl_sched_min_granularity.
ah, interesting. Since you have CONFIG_SCHED_DEBUG enabled, could you
please try to figure out what the best value for
/proc/sys/kernel_sched_latency, /proc/sys/kernel_sched_nr_latency and
/proc/sys/kernel_sched_min_granularity is?
there's a tuning constraint for kernel_sched_nr_latency:
- kernel_sched_nr_latency should always be set to
kernel_sched_latency/kernel_sched_min_granularity. (it's not a free
tunable)
i suspect a good approach would be to double the value of
kernel_sched_latency and kernel_sched_nr_latency in each tuning
iteration, while keeping kernel_sched_min_granularity unchanged. That
will excercise the tuning values of the 2.6.23 kernel as well.
Ingo
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