From: Folkert van Heusden <folkert@vanheusden.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mutex: have non-spinning mutexes on s390 by default
Date: Fri, 17 Apr 2009 23:42:12 +0200 [thread overview]
Message-ID: <20090417214212.GG10554@vanheusden.com> (raw)
In-Reply-To: <20090409174758.74abec87@osiris.boeblingen.de.ibm.com>
> The adaptive spinning mutexes will not always do what one would expect on
> virtualized architectures like s390. Especially the cpu_relax() loop in
> mutex_spin_on_owner might hurt if the mutex holding cpu has been scheduled
> away by the hypervisor.
> We would end up in a cpu_relax() loop when there is no chance that the
> state of the mutex changes until the target cpu has been scheduled again by
> the hypervisor.
> For that reason we should change the default behaviour to no-spin on s390.
Hmmm. Wouldn't this be a change that applies to ibm system p as wel?
E.g. with linux in an lpar.
Folkert van Heusden
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next prev parent reply other threads:[~2009-04-17 21:52 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-09 15:47 [PATCH] mutex: have non-spinning mutexes on s390 by default Heiko Carstens
2009-04-09 15:54 ` Peter Zijlstra
2009-04-09 16:14 ` Heiko Carstens
2009-04-09 16:48 ` Heiko Carstens
2009-04-09 16:53 ` Peter Zijlstra
2009-04-09 17:38 ` Peter Zijlstra
2009-04-09 17:50 ` Jeremy Fitzhardinge
2009-04-09 18:34 ` Peter Zijlstra
2009-04-09 18:12 ` [tip:core/urgent] " Heiko Carstens
2009-04-17 21:42 ` Folkert van Heusden [this message]
2009-04-20 12:01 ` [PATCH] " Heiko Carstens
2009-04-20 12:04 ` David Miller
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