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Subject: Re: [PATCH 4/7] perf: Check if HT is supported and enabled
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Stephane Eranian <eranian@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Lin Ming <ming.m.lin@intel.com>,
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Date: Tue, 04 Jan 2011 14:44:35 +0100
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On Tue, 2011-01-04 at 14:38 +0100, Stephane Eranian wrote:
> My solution at the time (2.6.30) was to do:
>         ht_enabled = cpumask_weight(__get_cpu_var(cpu_sibling_map)) > 1;

Won't that report a machine a HT disabled when you offline a sibling?
Which kinda defeats the purpose of our usage here, since we need to know
it before either sibling comes online.