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From: ebiederm@xmission.com (Eric W. Biederman)
To: tim.c.chen@linux.intel.com
Cc: Adrian Bunk <bunk@stusta.de>, Linus Torvalds <torvalds@osdl.org>,
       Andrew Morton <akpm@osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.19-rc5: known regressions
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Date: Mon, 13 Nov 2006 17:03:14 -0700
In-Reply-To: <1163458004.10806.276.camel@localhost.localdomain> (Tim Chen's
	message of "Mon, 13 Nov 2006 14:46:44 -0800")
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Tim Chen <tim.c.chen@linux.intel.com> writes:

> On Wed, 2006-11-08 at 22:10 -0700, Eric W. Biederman wrote:
>
>> 
>> Cool.  I'm glad to know it was simply a buggy lmbench.
>> 
>> What is sysconf(_SN_NPROCESSORS_ONLN) doing that it slows down as the
>> number of irqs increase?  It is a slow path certainly but possibly
>> something we should fix.  My hunch is cat /proc/cpuinfo...
>> 
>
> The increase in time of sysconf(_SN_NPROCESSORS_ONLN) call
> is within "show_stat" function after looking at profiling data.  
> There are a couple of loops that iterate over kstat_irqs 
> interrupt statistics and depend on NR_IRQS.  Doesn't 
> look like something we need to fix.

Thanks.

Eric