From: Andi Kleen <ak@suse.de>
To: Matt Mackall <mpm@selenic.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Marin Mitov <mitov@issp.bas.bg>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>
Subject: Re: is minimum udelay() not respected in preemptible SMP kernel-2.6.23?
Date: Thu, 8 Nov 2007 02:20:58 +0100 [thread overview]
Message-ID: <200711080220.59086.ak@suse.de> (raw)
In-Reply-To: <20071108010347.GP19691@waste.org>
> But I think we'd be best off stashing a single bit somewhere and
> checking it at migrate time (relatively infrequent) rather than
> copying and zeroing out a potentially enormous affinity mask every
> time we disable migration (often, and in fast paths). Perhaps adding
> TASK_PINNED to the task state flags would do it?
It would need to be a count to be able to nest it.
> > get_cpu() etc. could be changed to use this then too.
>
> Some users of get_cpu might be relying on it to avoid actual
> preemption. In other words, we should have introduced a
> migrate_disable() when we first discovered the preempt/per_cpu
> conflict.
Ok perhaps it would make sense to migrate it step by step :-
define a replacement for get_cpu and migrate over as users are getting
audited and eventually deprecate old one.
-Andi
next prev parent reply other threads:[~2007-11-08 1:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-07 17:21 is minimum udelay() not respected in preemptible SMP kernel-2.6.23? Marin Mitov
2007-11-07 20:30 ` Andrew Morton
2007-11-07 23:10 ` Andi Kleen
2007-11-08 0:20 ` Matt Mackall
2007-11-08 0:31 ` Andi Kleen
2007-11-08 1:03 ` Matt Mackall
2007-11-08 1:20 ` Andi Kleen [this message]
2007-11-08 2:44 ` Matt Mackall
2007-11-08 11:46 ` Avi Kivity
2007-11-08 15:10 ` Matt Mackall
2007-11-08 9:11 ` Peter Zijlstra
2007-11-08 15:43 ` Matt Mackall
2007-11-08 11:24 ` Marin Mitov
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