Re: Context switch storm

Am Freitag, den 03.11.2006, 14:38 +0000 schrieb Richard Huxton:
> creimer(at)brturbo(dot)com(dot)br wrote:
> >> If you can keep your numbers of clients down below the critical
> >> level, you should find the overall workload is fine.
> >
> > We have at about 600 connections. Is this a case to use a connection
> > pool (pg_pool) system?
>
> Possibly - that should help. I'm assuming that most of your queries are
> very short, so you could probably get that figure down a lot lower.
> You'll keep the same amount of queries running through the system, just
> queue them up.
that have
Ah, yes, now that you mention, avoid running many queries with a
similiar timing behaviour, PG8 seems to have a lock design that's very
bad for the memory architecture of the Xeons.

So running SELECT * FROM table WHERE id=1234567890; from 600 clients in
parallel can be quite bad than say a complicated 6-way join :(

Andreas

>
> > And why this happens only with 8.0 and 8.1 and not with the 7.4?
>
> Not sure. Maybe 8.x is making more intensive use of your memory,
> possibly with a change in your plans.
>