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Subject: Re: perf_events: questions about cpu_has_ht_siblings() and offcore
 support
From: Peter Zijlstra <peterz@infradead.org>
To: Stephane Eranian <eranian@google.com>
Cc: Lin Ming <ming.m.lin@intel.com>, LKML <linux-kernel@vger.kernel.org>,
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Date: Fri, 22 Apr 2011 16:47:58 +0200
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On Fri, 2011-04-22 at 16:41 +0200, Stephane Eranian wrote:
> I assume that's because hotplug
> cpu is inherently serialized. You cannot have a CPU going offline
> and one going online at the same time. is that right? 

Exactly, that's all serialized under the hotpug mutex