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Subject: Re: [patch v3]numa: add a sysctl to control interleave allocation
 granularity from each node to improve I/O performance
From: Shaohua Li <shaohua.li@intel.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Lameter <cl@linux.com>, lkml <linux-kernel@vger.kernel.org>,
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        David Rientjes <rientjes@google.com>
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Date: Thu, 15 Dec 2011 09:27:51 +0800
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On Thu, 2011-12-15 at 01:53 +0800, Andi Kleen wrote:
> > That's what I want to avoid letting each apps to explicitly do it, it's
> > a lot of burden.
> 
> Usually apps that set NUMA policy can change it. Most don't anyways.
> If it's just a script with numactl it's easily changed.
Hmm, why should apps set different granularity? the granularity change
is to speed up I/O, which should have the same value for all apps.

> > That's true only workload with heavy I/O wants this. but I don't expect
> > it will harm other workloads.
> 
> How do you know?
I can't imagine how it could harm. Some arches can use big pages, big
granularity should already been tested for years.

Thanks,
Shaohua