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 12:32:08 +0200 [thread overview]
Message-ID: <1224671528.7511.11.camel@marge.simson.net> (raw)
In-Reply-To: <1224669821.6871.16.camel@marge.simson.net>
On Wed, 2008-10-22 at 12:03 +0200, Mike Galbraith wrote:
> It has positive effects too, but IMHO, the bad outweigh the good.
BTW, most dramatic on the other end of the spectrum is pgsql+oltp. With
preemption as is, it collapses as load climbs to heavy with preemption
knobs at stock. Postgres uses user-land spinlocks and _appears_ to wake
others while these are still held. For this load, there is such a thing
as too much short-term fairness, preempting lock holder creates nasty
gaggle of contended lock spinners. It's curable with knobs, and I think
it's postgres's own fault, but may be wrong.
With that patch, pgsql+oltp scales perfectly.
-Mike
next prev parent reply other threads:[~2008-10-22 10:32 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 [this message]
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
2008-10-22 17:38 ` Peter Zijlstra
2008-10-22 17:56 ` Mike Galbraith
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