Re: PostgreSQL pgbench performance regression in 2.6.23+

From: Mike Galbraith
Date: Fri May 23 2008 - 19:47:27 EST

On Fri, 2008-05-23 at 19:18 -0400, Greg Smith wrote:
> On Fri, 23 May 2008, Mike Galbraith wrote:
> > It was running SCHED_BATCH, needed features=0 as well to
> > achieve O(1) batch performance.
> I figured out how to run pgbench with chrt in order to get SCHED_BATCH
> behavior, but I don't understand what you mean by features=0 here. Since
> I didn't see the same magnitude of different just using batch that seems
> important, where does that get set at?

/proc/sys/kernel/sched_features. You need CONFIG_SCHED_DEBUG to have
accsess to the scheduler tweakables.

> I'm also curious what hardware your results are coming from, to fit them
> into my larger pgbench results context space.

A grocery store Q6600 box.

> Got my 4-core system back on-line again today (found some bad RAM) and
> wanted to try another round of tests on that. Looks like you've defined 5
> test sets I should replicate:
> 2.6.22
> 2.6.22, batch
> 2.6.26.git
> 2.6.26.git, batch
> 2.6.26.git, batch + se.load.weight patch
> Should I still be trying Peter's se.waker patch as well in this mix
> somewhere?



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