Message-ID: <47BB4AB8.9020509@sgi.com>
Date: Tue, 19 Feb 2008 13:31:36 -0800
From: Mike Travis <travis@sgi.com>
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To: Paul Jackson <pj@sgi.com>
CC: Jens Axboe <jens.axboe@oracle.com>, Alan.Brunelle@hp.com,
       linux-kernel@vger.kernel.org, npiggin@suse.de, dgc@sgi.com,
       arjan@linux.intel.com
Subject: Re: IO queueing and complete affinity w/ threads: Some results
References: <47B0B69B.1050807@hp.com>	<47B46008.9020804@hp.com>	<20080218123717.GW23197@kernel.dk> <20080219151418.97557f0f.pj@sgi.com>
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Paul Jackson wrote:
> Jens wrote:
>> My main worry with the current code is the ->lock in the per-cpu
>> completion structure.
> 
> Drive-by-comment here:  Does the patch posted later this same day by Mike Travis:
> 
>   [PATCH 0/2] percpu: Optimize percpu accesses v3
> 
> help with this lock issue any?  (I have no real clue here -- just connecting
> up the pretty colored dots ;).
> 

I'm not sure of the context here but a big motivation for doing the
zero-based per_cpu variables was to optimize access to the local
per cpu variables to one instruction, reducing the need for locks.

-Mike
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