linux-kernel - Re: [PATCH] x86/mce: Lower throttling MCE messages to warnings

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Message-ID: <1dfc2bf57335b7eb9f130cc791db76655fb5b8f4.camel@perches.com>
Date:   Wed, 09 Oct 2019 11:05:37 -0700
From:   Joe Perches <joe@...ches.com>
To:     Borislav Petkov <bp@...en8.de>, Benjamin Berg <bberg@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Christian Kellner <ckellner@...hat.com>,
        Tony Luck <tony.luck@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-edac@...r.kernel.org
Subject: Re: [PATCH] x86/mce: Lower throttling MCE messages to warnings

On Wed, 2019-10-09 at 19:56 +0200, Borislav Petkov wrote:
> On Wed, Oct 09, 2019 at 05:54:24PM +0200, Benjamin Berg wrote:
> > On modern CPUs it is quite normal that the temperature limits are
> > reached and the CPU is throttled. In fact, often the thermal design is
> > not sufficient to cool the CPU at full load and limits can quickly be
> > reached when a burst in load happens. This will even happen with
> > technologies like RAPL limitting the long term power consumption of
> > the package.
> > 
> > So these messages do not usually indicate a hardware issue (e.g.
> > insufficient cooling). Log them as warnings to avoid confusion about
> > their severity.
[]
> > diff --git a/arch/x86/kernel/cpu/mce/therm_throt.c b/arch/x86/kernel/cpu/mce/therm_throt.c
[]
> > @@ -188,7 +188,7 @@ static void therm_throt_process(bool new_event, int event, int level)
> >  	/* if we just entered the thermal event */
> >  	if (new_event) {
> >  		if (event == THERMAL_THROTTLING_EVENT)
> > -			pr_crit("CPU%d: %s temperature above threshold, cpu clock throttled (total events = %lu)\n",
> > +			pr_warn("CPU%d: %s temperature above threshold, cpu clock throttled (total events = %lu)\n",
> >  				this_cpu,
> >  				level == CORE_LEVEL ? "Core" : "Package",
> >  				state->count);
> > -- 
> 
> This has carried over since its very first addition in
> 
> commit 3867eb75b9279c7b0f6840d2ad9f27694ba6c4e4
> Author: Dave Jones <davej@...e.de>
> Date:   Tue Apr 2 20:02:27 2002 -0800
> 
>     [PATCH] x86 bluesmoke update.
>     
>     o  Make MCE compile time optional       (Paul Gortmaker)
>     o  P4 thermal trip monitoring.          (Zwane Mwaikambo)
>     o  Non-fatal MCE logging.               (Me)
> 
> 
> It used to be KERN_EMERG back then, though.
> 
> And yes, this issue has come up in the past already so I think I'll take
> it. I'll just give Intel folks a couple of days to object should there
> be anything to object to.

Perhaps this should be

	pr_warn_ratelimited(...)

as the temperature changes can be relatively quick.