Re: 2.6.26 kernel and PostgreSQL

--- On Mon, 13/4/09, Greg Smith <gsmith(at)gregsmith(dot)com> wrote:

> From: Greg Smith <gsmith(at)gregsmith(dot)com>
> Subject: Re: [PERFORM] 2.6.26 kernel and PostgreSQL
> To: "Glyn Astill" <glynastill(at)yahoo(dot)co(dot)uk>
> Cc: pgsql-performance(at)postgresql(dot)org, "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)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