--- On Mon, 13/4/09, Greg Smith <gsmith@gregsmith.com> wrote:
> From: Greg Smith <gsmith@gregsmith.com>
> Subject: Re: [PERFORM] 2.6.26 kernel and PostgreSQL
> To: "Glyn Astill" <glynastill@yahoo.co.uk>
> Cc: pgsql-performance@postgresql.org, "Kevin Grittner" <Kevin.Grittner@wicourts.gov>
> Date: Monday, 13 April, 2009, 9:25 AM
> On Fri, 10 Apr 2009, Glyn Astill wrote:
>
> > So it was only for connections over a unix socket, but
> wow; it's still an ongoing issue.
>
> The problem is actually with pgbench when running on a UNIX
> socket, not with the PostgreSQL server itself. On my tests,
> the actual database server itself seems to work just as well
> or better on later kernels that use the new scheduler than
> the older scheduler did.
>
> Basically, if all these apply:
>
> 1) You are running pgbench
> 2) You're running a quick statement, such as a simple
> select, that gives
> > 10000TPS or so
> 3) Connecting via UNIX socket
> 4) Clients > around 10
> 5) Linux kernel >=2.6.23 (which means CFS as the
> scheduler)
> 6) The CFS features are at their defaults
> (SCHED_FEAT_SYNC_WAKEUPS is on)
>
> You'll get weird results. Change any of those and
> things are still fine.
>
Ace, I'll upgrade today then. Thanks Greg