From: Gautham R Shenoy <ego@in.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>,
"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>,
Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: specjbb2005 and aim7 regression with 2.6.32-rc kernels
Date: Mon, 9 Nov 2009 15:14:25 +0530 [thread overview]
Message-ID: <20091109094425.GA26733@in.ibm.com> (raw)
In-Reply-To: <1257758104.4108.152.camel@laptop>
On Mon, Nov 09, 2009 at 10:15:04AM +0100, Peter Zijlstra wrote:
> On Mon, 2009-11-09 at 08:09 +0100, Mike Galbraith wrote:
> > + smp_read_barrier_depends();
> > cpumask_setall(cpus);
> > + cpumask_and(cpus, cpus, cpu_online_mask);
>
>
> how about: cpumask_copy(cpus, cpu_online_mask); ?
>
> Also, iirc cpu_online_mask is guaranteed stable when preemption is
> disabled, otherwise you need to use get/put_online_cpus(), an
> rmb_depends() won't do.
preempt_disable() guarantees that any cpus won't go offline, since we
use stop_machine() to take CPUs offline. I don't think it provides cover
against new cpus coming online.
--
Thanks and Regards
gautham
next prev parent reply other threads:[~2009-11-09 9:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-06 7:38 specjbb2005 and aim7 regression with 2.6.32-rc kernels Zhang, Yanmin
2009-11-06 8:02 ` Mike Galbraith
2009-11-06 8:04 ` Ingo Molnar
2009-11-09 6:19 ` Zhang, Yanmin
2009-11-09 7:09 ` Mike Galbraith
2009-11-09 9:15 ` Peter Zijlstra
2009-11-09 9:44 ` Gautham R Shenoy [this message]
2009-11-09 9:57 ` Mike Galbraith
2009-11-09 9:55 ` Mike Galbraith
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