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Subject: Re: 2.6.19-rc5: known regressions
From: Tim Chen <tim.c.chen@linux.intel.com>
Reply-To: tim.c.chen@linux.intel.com
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Adrian Bunk <bunk@stusta.de>, Linus Torvalds <torvalds@osdl.org>,
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Date: Mon, 13 Nov 2006 14:46:44 -0800
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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.

Tim