| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: We really ought to do something about O_DIRECT and data=journalled on ext4 |
| Date: | 2010-12-07 02:12:25 |
| Message-ID: | 4CFD9809.20608@agliodbs.com |
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| Lists: | pgsql-hackers |
On 12/6/10 6:10 PM, Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Mon, Dec 6, 2010 at 9:04 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>>> Actually, on OSX 10.5.8, o_dsync and fdatasync aren't even available.
>>> From my run, it looks like even so regular fsync might be better than
>>> open_sync.
>
>> But I think you need to use fsync_writethrough if you actually want durability.
>
> Yeah. Unless your laptop contains an SSD, those numbers are garbage on
> their face. So that's another problem with test_fsync: it omits
> fsync_writethrough.
Yeah, the issue with test_fsync appears to be that it's designed to work
without os-specific switches no matter what, not to accurately reflect
how we access wal.
I'll see if I can do better.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
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