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Subject: Re: [PATCH v3] mm, sysctl: make NUMA stats configurable
To: Michal Hocko <mhocko@kernel.org>
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Cc: kemi <kemi.wang@intel.com>, "Luis R . Rodriguez" <mcgrof@kernel.org>,
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        Proc sysctl <linux-fsdevel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>,
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        Aaron Lu <aaron.lu@intel.com>
From: Dave Hansen <dave.hansen@linux.intel.com>
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Date: Tue, 10 Oct 2017 08:39:47 -0700
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On 10/10/2017 07:57 AM, Michal Hocko wrote:
>> But, let's be honest, this leaves us with an option that nobody is ever
>> going to turn on.  IOW, nobody except a very small portion of our users
>> will ever see any benefit from this.
> But aren't those small groups who would like to squeeze every single
> cycle out from the page allocator path the targeted audience?

They're the reason we started looking at this.  They also care the most.

But, the cost of these stats, especially we get more and more cores in a
NUMA node is really making them show up in profiles.  It would be nice
to get rid of them there, too.

Aaron, do you remember offhand how much of the allocator overhead was
coming from NUMA stats?