linux-kernel - Re: [PATCH] x86/tsc: Extend the watchdog check exemption to 4S/8S machine

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Message-ID: <Y0V3Snlqvz2+1UUQ@hirez.programming.kicks-ass.net>
Date:   Tue, 11 Oct 2022 16:01:46 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Zhang Rui <rui.zhang@...el.com>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Feng Tang <feng.tang@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, tim.c.chen@...el.com,
        Xiongfeng Wang <wangxiongfeng2@...wei.com>,
        Yu Liao <liaoyu15@...wei.com>
Subject: Re: [PATCH] x86/tsc: Extend the watchdog check exemption to 4S/8S
 machine

On Tue, Oct 11, 2022 at 09:33:26PM +0800, Zhang Rui wrote:

> topology_max_packages() or variable logical_packages can tell the
> maximum packages.
> But this check_system_tsc_reliable() is done in early boot phase where
> we have boot cpu only. And the cpu topology is not built up at this
> stage.

Is there a problem with disabling the TSC watchdog later in boot --
after SMP bringup for example?