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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Rick Otten <rottenwindfish@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Queries intermittently slow
Date: Thu, 7 Jan 2016 20:47:59 +0100
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On 2016-01-07 13:34:51 -0500, Tom Lane wrote:
> It's fairly well established that the implementation of transparent
> huge pages in Linux kernels from the 2.6-or-so era sucks, and you're
> best off turning it off if you care about consistency of performance.

I think the feature wasn't introduced in original 2.6 kernels (3.2 or
so?), but red hat had backported it to their 2.6.32 kernel.


> I am not sure whether modern kernels have improved this area.

I think the problem has largely been solved around 3.16. Around 4.1 I
could still  reproduce problems, but the regressions were only in the
sub 10% range in my test workload.


Andres


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