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From: Joel Schopp <jschopp@austin.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: ego@in.ibm.com, Andreas Herrmann <andreas.herrmann3@amd.com>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/2] powerpc: implement arch_scale_smt_power for Power7
Date: Wed, 20 Jan 2010 16:44:01 -0600	[thread overview]
Message-ID: <4B578731.2060709@austin.ibm.com> (raw)
In-Reply-To: <1264020517.4283.1117.camel@laptop>

Peter Zijlstra wrote:
> On Wed, 2010-01-20 at 14:04 -0600, Joel Schopp wrote:
>   
>> On Power7 processors running in SMT4 mode with 2, 3, or 4 idle threads 
>> there is performance benefit to idling the higher numbered threads in
>> the core.  
>>     
>
> So this is an actual performance improvement, not only power savings?
>   
Yes.

>
>
> And you just wrecked x86 ;-)
>
> It has an smt_power implementation that tries to measure smt gains using
> aperf/mperf, trouble is that this represents the actual performance not
> the capacity. This has the problem that when idle it represents 0
> capacity and will not attract work.
>
> Coming up with something that actually works there is on the todo list,
> I was thinking perhaps temporal maximums from !idle.
>
> So if you want to go with this, you'll need to stub out
> arch/x86/kernel/cpu/sched.c
>   

OK.  Guess I now will have a 3 patch series, with a patch to stub out 
the x86 broken version.

Care to take Gautham's bugfix patch (patch 1/2) now, since it just fixes 
a bug?  You'll need it if you ever try to make the x86 broken version work.

  parent reply	other threads:[~2010-01-20 22:44 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-20 20:00 [PATCH 0/2] sched: arch_scale_smt_powers Joel Schopp
2010-01-20 20:02 ` [PATCH 1/2] sched: Fix the place where group powers are updated Joel Schopp
2010-01-26 23:28   ` [PATCHv2 1/2] sched: enable ARCH_POWER Joel Schopp
2010-01-28 23:20     ` [PATCHv3 " Joel Schopp
2010-02-05 20:57       ` [PATCHv4 " Joel Schopp
2010-01-20 20:04 ` [PATCH 2/2] powerpc: implement arch_scale_smt_power for Power7 Joel Schopp
2010-01-20 20:48   ` Peter Zijlstra
2010-01-20 21:58     ` Michael Neuling
2010-01-20 22:44     ` Joel Schopp [this message]
2010-01-21  8:27       ` Peter Zijlstra
2010-01-20 21:04   ` Michael Neuling
2010-01-20 22:09     ` Joel Schopp
2010-01-24  3:00       ` Benjamin Herrenschmidt
2010-01-25 17:50         ` Joel Schopp
2010-01-26  4:23           ` Benjamin Herrenschmidt
2010-01-20 21:33   ` Benjamin Herrenschmidt
2010-01-20 22:36     ` Joel Schopp
2010-01-26 23:28   ` [PATCHv2 " Joel Schopp
2010-01-27  0:52     ` Benjamin Herrenschmidt
2010-01-28 22:39       ` Joel Schopp
2010-01-29  1:23         ` Benjamin Herrenschmidt
2010-01-28 23:20     ` [PATCHv3 " Joel Schopp
2010-01-28 23:24       ` Joel Schopp
2010-01-29  1:23         ` Benjamin Herrenschmidt
2010-01-29 10:13           ` Peter Zijlstra
2010-01-29 18:34             ` Joel Schopp
2010-01-29 18:41           ` Joel Schopp
2010-02-05 20:57         ` [PATCHv4 " Joel Schopp
2010-02-14 10:12           ` Peter Zijlstra
2010-02-17 22:20             ` Michael Neuling
2010-02-18 13:17               ` Peter Zijlstra
2010-02-18 13:19                 ` Peter Zijlstra
2010-02-18 16:28                 ` Joel Schopp
2010-02-18 17:08                   ` Peter Zijlstra
2010-02-19  6:05                 ` Michael Neuling
2010-02-19 10:01                   ` Peter Zijlstra
2010-02-19 11:01                     ` Michael Neuling
2010-02-23  6:08                       ` Michael Neuling
2010-02-23 16:24                         ` Peter Zijlstra
2010-02-23 16:30                           ` Peter Zijlstra
2010-02-24  6:07                           ` Michael Neuling
2010-02-24 11:13                             ` Michael Neuling
2010-02-24 11:58                               ` Michael Neuling
2010-02-27 10:21                               ` Michael Neuling
2010-03-02 14:44                                 ` Peter Zijlstra
2010-03-04 22:28                                   ` Michael Neuling
2010-01-29 12:25       ` [PATCHv3 " Gabriel Paubert
2010-01-29 16:26         ` Joel Schopp
2010-01-26 23:27 ` [PATCHv2 0/2] sched: arch_scale_smt_powers v2 Joel Schopp
2010-01-28 23:20   ` [PATCHv3 0/2] sched: arch_scale_smt_powers Joel Schopp
2010-02-05 20:57     ` [PATCHv4 " Joel Schopp

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