Message-ID: <4B5DD9F1.2010002@austin.ibm.com>
Date: Mon, 25 Jan 2010 11:50:41 -0600
From: Joel Schopp <jschopp@austin.ibm.com>
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Michael Neuling <mikey@neuling.org>, Ingo Molnar <mingo@elte.hu>,
       ego@in.ibm.com, linuxppc-dev@lists.ozlabs.org,
       Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] powerpc: implement arch_scale_smt_power for Power7
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Benjamin Herrenschmidt wrote:
> On Wed, 2010-01-20 at 16:09 -0600, Joel Schopp wrote:
>   
>> I can turn that into a conditional branch (case statement) with a shift 
>> for the common 1,2,4 cases which should cover all procs available today 
>> falling back to a divide for any theoretical future processors that do 
>> other numbers of threads. 
>>     
>
> Look at the cputhreads.h implementation ... Today we only support
> power-of-two numbers of threads.
>   
I've run 3 threads using cpu hotplug to offline 1 of the 4.  It's 
certainly a stupid idea, but there you go.
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