linux-kernel - Re: [PATCH v4] x86/tsc: Use topology_max

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Message-ID: <878qxh5r6w.ffs@tglx>
Date: Wed, 31 Jul 2024 20:53:11 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Feng Tang <feng.tang@...el.com>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...el.com>, "H .
 Peter Anvin" <hpa@...or.com>, Peter Zijlstra <peterz@...radead.org>,
 x86@...nel.org, paulmck@...nel.org, rui.zhang@...el.com, Waiman Long
 <longman@...hat.com>, linux-kernel@...r.kernel.org
Cc: Feng Tang <feng.tang@...el.com>, Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH v4] x86/tsc: Use topology_max_packages() to get package
 number

On Mon, Jul 29 2024 at 10:12, Feng Tang wrote:
>  	pr_info("Allowing %u present CPUs plus %u hotplug CPUs\n", assigned, disabled);
> -	if (topo_info.nr_rejected_cpus)
> +	if (topo_info.nr_rejected_cpus) {
>  		pr_info("Rejected CPUs %u\n", topo_info.nr_rejected_cpus);
> +		if (__max_logical_packages <= 4)
> +			pr_info("TSC might be buggered due to the rejected CPUs\n");

I'm not really convinced of the value of this message.

People who limit their CPUs on the command line or at compile time
really should know what they are doing. The kernel already tells that
there are rejected CPUs and that extra TSC info is just annoying and
confusing noise for people who run that and have a perfectly working TSC
on a single/dual/quad socket machine.

I just drop that noise.

Thanks,

        tglx