Skip site navigation (1) Skip section navigation (2)

Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?

From: Scott Carey <scott(at)richrelevance(dot)com>
To: Mladen Gogala <mladen(dot)gogala(at)vmsinfo(dot)com>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, "pgsql-performance(at)postgresql(dot)org"<pgsql-performance(at)postgresql(dot)org>
Subject: Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?
Date: 2010-11-17 19:26:30
Message-ID: B934F82D-E22F-42E7-A69D-A9C409C96DBE@richrelevance.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Nov 16, 2010, at 4:05 PM, Mladen Gogala wrote:

> Josh Berkus wrote:
>> On 11/16/10 12:39 PM, Greg Smith wrote:
>> 
>>> I want to next go through and replicate some of the actual database
>>> level tests before giving a full opinion on whether this data proves
>>> it's worth changing the wal_sync_method detection.  So far I'm torn
>>> between whether that's the right approach, or if we should just increase
>>> the default value for wal_buffers to something more reasonable.
>>> 
>> 
>> We'd love to, but wal_buffers uses sysV shmem.
>> 
>> 
> Speaking of the SYSV SHMEM, is it possible to use huge pages?

RHEL 6  and friends have transparent hugepage support.  I'm not sure if they yet transparently do it for SYSV SHMEM, but they do for most everything else.  Sequential traversal of a process heap is several times faster with hugepages.  Unfortunately, postgres doesn't organize its blocks in its shared_mem to be sequential for a relation.  So it might not matter much.

> 
> -- 
> 
> Mladen Gogala 
> Sr. Oracle DBA
> 1500 Broadway
> New York, NY 10036
> (212) 329-5251
> http://www.vmsinfo.com 
> The Leader in Integrated Media Intelligence Solutions
> 
> 
> 
> 
> -- 
> Sent via pgsql-performance mailing list (pgsql-performance(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance


In response to

pgsql-performance by date

Next:From: Scott CareyDate: 2010-11-17 20:19:10
Subject: Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?
Previous:From: Scott CareyDate: 2010-11-17 18:58:36
Subject: Re: How to achieve sustained disk performance of 1.25 GB write for 5 mins

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group