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From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: 'Ingo Molnar' <mingo@elte.hu>, Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: RE: boot-time slowdown for measure_migration_cost
Date: Mon, 30 Jan 2006 19:26:04 +0000	[thread overview]
Message-ID: <200601301926.k0UJQBg16647@unix-os.sc.intel.com> (raw)
In-Reply-To: <20060130172140.GB11793@elte.hu>
In-Reply-To: <200601271403.27065.bjorn.helgaas@hp.com>

Ingo Molnar wrote on Monday, January 30, 2006 9:22 AM
> - in kernel/sched.c, decrease ITERATIONS from 2 to 1. This will make the 
>   measurement more noisy though.
> 
> - in kernel/sched.c, change this line:
> 
>                 size = size * 20 / 19;
> 
>   to:
> 
>                 size = size * 10 / 9;
> 
>   this will probably halve the cost - against at the expense of 
>   accuracy and statistical stability.

I think the kernel should keep the accuracy and stability.  One option
would be by default not to measure the migration cost.  For people who
wants to have an accurate scheduler parameter, they can turn on a boot
time option to do the measure.

- Ken


  parent reply	other threads:[~2006-01-30 19:26 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-01-27 21:03 boot-time slowdown for measure_migration_cost Bjorn Helgaas
2006-01-27 21:48 ` Luck, Tony
2006-01-27 22:08   ` Prarit Bhargava
2006-01-30 17:21 ` Ingo Molnar
2006-01-30 18:53   ` Luck, Tony
2006-01-30 19:24     ` Ingo Molnar
2006-01-30 20:00       ` Luck, Tony
2006-01-30 20:43         ` Prarit Bhargava
2006-01-30 20:52           ` Prarit Bhargava
2006-01-30 20:43     ` John Hawkes
2006-01-30 19:26 ` Chen, Kenneth W [this message]
2006-02-01  0:50 ` Chuck Ebbert

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