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Date: Tue, 10 May 2016 08:51:33 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Josef Bacik <jbacik@fb.com>, LKML <linux-kernel@vger.kernel.org>,
        kernel-team <Kernel-team@fb.com>, x86@kernel.org,
        Kan Liang <kan.liang@intel.com>
Subject: Re: Regression introduced by cf6d445f68974d0b15a14cf6021be38a91f2b5d8
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On Mon, May 09, 2016 at 09:48:18PM +0200, Thomas Gleixner wrote:

> So that explains the wreckage you are seing. We have two options to deal with
> this:
> 
> 1) Make intel_num_cpu_cores() a NOOP for SMP=n, so x86_max_cores = 1

This I think; because:

> 
> 2) Make detect_extended_topology() functional for SMP=n, so the real number of
>    cores is detected

UP has no business 'knowing' anything about cores/threads and general
topology stuff.