From: | Josh Berkus <josh(at)agliodbs(dot)com> |
---|---|
To: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Major Linux performance regression; shouldn't we be worried about RHEL6? |
Date: | 2010-11-05 22:11:43 |
Message-ID: | 4CD4811F.60905@agliodbs.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
> The main change here was discussed back in January:
> http://archives.postgresql.org/message-id/4B512D0D.4030909@2ndquadrant.com
>
> What I've been doing about this is the writing leading up to
> http://wiki.postgresql.org/wiki/Reliable_Writes so that when RHEL6 does
> ship, we have a place to point people toward that makes it better
> documented that the main difference here is a reliability improvement
> rather than a performance regression. I'm not sure what else we can do
> here, other than organizing more testing for kernel bugs in this area on
> RHEL6. The only way to regain the majority of the "lost" performance
> here is to turn off synchronous_commit in the default config.
Yeah, I was looking at that. However, there seems to be some
indications that there was a drop in performance specifically in 2.6.32
which went beyond fixing the reliability:
http://www.phoronix.com/scan.php?page=article&item=linux_2636_btrfs&num=1
However, Phoronix doesn't say what sync option they're using; quite
likely it's O_DSYNC. Unfortunately, the fact that users now need to be
aware of the fsync_method again, after having it set automatically for
them for the last 4 years, is a usability regression for *us*. Anything
that's reasonable for us to do about it?
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
From | Date | Subject | |
---|---|---|---|
Next Message | Scott Carey | 2010-11-05 22:30:22 | Re: Major Linux performance regression; shouldn't we be worried about RHEL6? |
Previous Message | Josh Berkus | 2010-11-05 22:07:09 | Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1? |