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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>,
        linux-mm <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jens Axboe <axboe@kernel.dk>,
        "lee.schermerhorn@hp.com" <lee.schermerhorn@hp.com>,
        David Rientjes <rientjes@google.com>
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Date: Mon, 09 Jan 2012 15:31:52 +0800
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On Thu, 2011-12-15 at 09:27 +0800, Shaohua Li wrote:
> 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.
ping ...