linux-kernel - Re: [Patch v2 2/2] x86/tsc: use logical_packages as a better estimation of socket numbers

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Message-ID: <20230616094205.GC4253@hirez.programming.kicks-ass.net>
Date:   Fri, 16 Jun 2023 11:42:05 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Zhang, Rui" <rui.zhang@...el.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "Tang, Feng" <feng.tang@...el.com>,
        "Chen, Tim C" <tim.c.chen@...el.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "x86@...nel.org" <x86@...nel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "paulmck@...nel.org" <paulmck@...nel.org>,
        "Woodhouse, David" <dwmw@...zon.co.uk>
Subject: Re: [Patch v2 2/2] x86/tsc: use logical_packages as a better
 estimation of socket numbers

On Fri, Jun 16, 2023 at 09:19:18AM +0000, Zhang, Rui wrote:

> According to the MADT, there are indeed 40 valid CPUs. And then 80 CPUs
> with 
> 
> APIC ID		: FF
> enabled		: 0
> Online capable	: 0
> 
> a dumb question, why are these CPUs added into the possible_mask?
> I can dig into this later but I just don't have a quick answer at the
> moment.

I really don't know.. I've not gotten around to reading that part of the
x86 code yet.