pg.ddx.io  pgsql-performance@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: Jim Nasby <Jim.Nasby@BlueTreble.com>
To: 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 15:04:33 -0600
Message-ID: <568ED2E1.6060107@BlueTreble.com> (raw)
In-Reply-To: <20160107194759.GM7650@awork2.anarazel.de>
References: <28587.1452097950@sss.pgh.pa.us>
	<C8BD1285-53CA-49B5-9481-E2CD4497FCF4@motus.com>
	<568DE640.5070508@BlueTreble.com>
	<F6E95891-A671-4027-86FB-418093483231@motus.com>
	<13261.1452179944@sss.pgh.pa.us>
	<AF8BAC52-69E0-466C-988C-8A896E5B720F@motus.com>
	<9E456947-7273-4D62-A5A1-D66F24052A00@yahoo.com>
	<B54B8CCF-E824-4689-A8C3-CD7626D41E77@motus.com>
	<CAMAYy4LwAeM7phr=9_oG2MgJF_7pPfQeCJio4BwXBRRcQRKkOg@mail.gmail.com>
	<13016.1452191691@sss.pgh.pa.us>
	<20160107194759.GM7650@awork2.anarazel.de>
List-Unsubscribe:  <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>

On 1/7/16 1:47 PM, Andres Freund wrote:
> 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.

BTW, looks like Scott blogged about this along with some nice graphs: 
https://sdwr98.wordpress.com/2016/01/07/transparent-huge-pages-or-why-dbas-are-great/
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com


-- 
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance



view thread (18+ messages)

Message-ID: <568ED2E1.6060107@BlueTreble.com>
Permalink:  ../568ED2E1.6060107@BlueTreble.com/
Also on:    postgresql.org/message-id/568ED2E1.6060107@BlueTreble.com

 · 

reply
Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-performance@postgresql.org
  Cc: Jim.Nasby@BlueTreble.com, andres@anarazel.de, tgl@sss.pgh.pa.us, rottenwindfish@gmail.com
  Subject: Re: Queries intermittently slow
  In-Reply-To: <568ED2E1.6060107@BlueTreble.com>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox