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Date: Fri, 29 Apr 2011 16:09:17 +0200
From: Andreas Herrmann <andreas.herrmann3@amd.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Ingo Molnar <mingo@elte.hu>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Anton Blanchard <anton@au1.ibm.com>,
        Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
        Suresh Siddha <suresh.b.siddha@intel.com>,
        Venkatesh Pallipadi <venki@google.com>, Paul Turner <pjt@google.com>,
        Mike Galbraith <efault@gmx.de>, Thomas Gleixner <tglx@linutronix.de>,
        Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [PATCH 04/23] sched: Change NODE sched_domain group creation
Message-ID: <20110429140917.GD22001@alberich.amd.com>
References: <20110407120941.400629539@chello.nl>
 <20110407122941.978111700@chello.nl>
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On Thu, Apr 07, 2011 at 08:09:45AM -0400, Peter Zijlstra wrote:
> The NODE sched_domain is 'special' in that it allocates sched_groups
> per CPU, instead of sharing the sched_groups between all CPUs.
> 
> While this might have some benefits on large NUMA and avoid remote
> memory accesses when iterating the sched_groups, this does break
> current code that assumes sched_groups are shared between all
> sched_domains (since the dynamic cpu_power patches).
> 
> So refactor the NODE groups to behave like all other groups.
> 
> (The ALLNODES domain again shared its groups across the CPUs for some
> reason).
> 
> If someone does measure a performance decrease due to this change we

[...]

Will do some performance sniff tests to check this.


Andreas

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