linux-kernel - Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal vector altogether

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Date:   Tue, 14 Apr 2020 23:40:48 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
        x86@...nel.org, arnd@...db.de, srinivas.pandruvada@...ux.intel.com,
        bberg@...hat.com, bp@...e.de,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Subject: Re: [PATCH 3/3] x86/mce/therm_throt: allow disabling the thermal
 vector altogether

On Tue, Apr 07, 2020 at 12:33:45AM -0600, Jason A. Donenfeld wrote:
> The thermal IRQ handler uses 1.21% CPU on my system when it's hot from
> compiling things. Indeed looking at /proc/interrupts reveals quite a lot
> of events coming in. Beyond logging them, the existing drivers on the
> system don't appear to do very much that I'm interested in. So, add a
> way to disable this entirely so that I can regain precious CPU cycles.

Why is this MCE code?!? hysterical raisins?

Anyway, I wonder if this is something we should hook up to
SCHED_THERMAL_PRESSURE, Rafael?

> diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
> index f996ffb887bc..d14f1922fb49 100644
> --- a/arch/x86/kernel/cpu/mce/intel.c
> +++ b/arch/x86/kernel/cpu/mce/intel.c
> @@ -511,7 +511,8 @@ static void intel_ppin_init(struct cpuinfo_x86 *c)
>  
>  void mce_intel_feature_init(struct cpuinfo_x86 *c)
>  {
> -	intel_init_thermal(c);
> +	if (IS_ENABLED(CONFIG_X86_THERMAL_VECTOR))
> +		intel_init_thermal(c);
>  	intel_init_cmci();
>  	intel_init_lmce();
>  	intel_ppin_init(c);
> -- 
> 2.26.0
>