linux-kernel - Re: [PATCH 1/2] x86, mce, therm_throt: Optimize logging of thermal throttle messages

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Message-ID: <20191018132309.GD17053@zn.tnic>
Date:   Fri, 18 Oct 2019 15:23:09 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     "Luck, Tony" <tony.luck@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "bberg@...hat.com" <bberg@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "hdegoede@...hat.com" <hdegoede@...hat.com>,
        "ckellner@...hat.com" <ckellner@...hat.com>
Subject: Re: [PATCH 1/2] x86, mce, therm_throt: Optimize logging of thermal
 throttle messages

On Fri, Oct 18, 2019 at 05:26:36AM -0700, Srinivas Pandruvada wrote:
> Server/desktops generally rely on the embedded controller for FAN
> control, which  kernel have no control. For them this warning helps to
> either bring in additional cooling or fix existing cooling.

How exactly does this warning help? A detailed example please.

> If something needs to force throttle from kernel, then we should use
> some offset from the max temperature (aka TJMax), instead of this
> warning threshold. Then we can use idle injection or change duty cycle
> of CPU clocks.

Yes, as I said, all this needs to be properly defined first. That is,
*if* there's even need for reacting to thermal interrupts in the kernel.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette