| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: wal_buffers, redux |
| Date: | 2012-03-14 03:18:59 |
| Message-ID: | CA+TgmobjYLxLojw2SaDnPX6ch7LtbdrK0QSJ5czsTXiVg8OTCA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Mar 13, 2012 at 6:44 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>> That's a speedup of nearly a factor of two, so clearly fsync-related
>> stalls are a big problem here, even with wal_buffers cranked up
>> through the ceiling.
>
> Hmmmm. Do you have any ability to test on XFS?
It seems I do.
XFS, with fsync = on:
tps = 14746.687499 (including connections establishing)
XFS, with fsync = off:
tps = 25121.876560 (including connections establishing)
No real dramatic difference there, maybe a bit slower.
On further thought, it may be that this is just a simple case of too
many checkpoints. With fsync=off, we don't have to actually write all
that dirty data back to disk. I'm going to try cranking up
checkpoint_segments and see what happens.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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