From: Mike Galbraith <efault@gmx.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/4] pending scheduler updates
Date: Wed, 22 Oct 2008 15:05:12 +0200 [thread overview]
Message-ID: <1224680712.15904.21.camel@marge.simson.net> (raw)
In-Reply-To: <20081022124240.GD25536@elte.hu>
On Wed, 2008-10-22 at 14:42 +0200, Ingo Molnar wrote:
> * Mike Galbraith <efault@gmx.de> wrote:
>
> > > > With that patch, pgsql+oltp scales perfectly.
> > >
> > > hm, tempting.
> >
> > I disagree. Postgres's scaling problem is trivially corrected by
> > twiddling knobs (or whatnot). [...]
>
> okay, then we need to document it a bit more: what knobs need twiddling
> to make it scale perfectly?
Twiddle sched_wakeup_granularity_ns or just turn FAIR_SLEEPERS off for
best pgsql+oltp scalability. Pgsql+oltp collapse is delicate. It
doesn't take much to send it one way or the other. Cut preempt a wee
bit, and it can snap right into shape.
I think we need to penalize sleepers a wee bit as load climbs in general
though, everybody begins to like preemption less as load increases.
Mysql+oltp improves as well, and it loves preempt at modest load.
-Mike
next prev parent reply other threads:[~2008-10-22 13:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-17 17:27 [PATCH 0/4] pending scheduler updates Peter Zijlstra
2008-10-17 17:27 ` [PATCH 1/4] sched: optimize group load balancer Peter Zijlstra
2008-10-17 17:27 ` [PATCH 2/4] sched: fair scheduler should not resched rt tasks Peter Zijlstra
2008-10-17 17:27 ` [PATCH 3/4] sched: revert back to per-rq vruntime Peter Zijlstra
2008-10-17 17:27 ` [PATCH 4/4] sched: fix wakeup preemption Peter Zijlstra
2008-10-20 21:57 ` Chris Friesen
2008-10-20 12:05 ` [PATCH 0/4] pending scheduler updates Ingo Molnar
2008-10-21 17:35 ` Srivatsa Vaddagiri
2008-10-22 9:40 ` Ingo Molnar
2008-10-22 10:03 ` Mike Galbraith
2008-10-22 10:32 ` Mike Galbraith
2008-10-22 12:10 ` Ingo Molnar
2008-10-22 12:38 ` Mike Galbraith
2008-10-22 12:42 ` Ingo Molnar
2008-10-22 13:05 ` Mike Galbraith [this message]
2008-10-22 17:38 ` Peter Zijlstra
2008-10-22 17:56 ` Mike Galbraith
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