linux-kernel - Re: [PATCH] x86: auto poll/interrupt mode switch for CMC to stop CMC storm

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Date:	Thu, 24 May 2012 19:34:05 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Borislav Petkov <bp@...64.org>,
	Chen Gong <gong.chen@...ux.intel.com>,
	"Luck, Tony" <tony.luck@...el.com>,
	"x86@...nel.org" <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] x86: auto poll/interrupt mode switch for CMC to stop CMC
 storm

On Thu, May 24, 2012 at 12:01:13PM +0200, Thomas Gleixner wrote:
> Aside of that machine_check_poll is called from other places as
> well. So looking at mce_timer_start() which is surprisingly the timer
> callback:
> 
> The poll timer rate is self adjusting to intervals down to HZ/100. So
> when you get into a state where the timer rate becomes lower than HZ/5
> we'll trigger that CMCI storm in software and queue work even on
> machines which do not support CMCI or have it disabled. Brilliant,
> isn't it?
> 
> So that rate check belongs into intel_treshold_interrupt() and wants a
> intel specific callback in mce_start_timer() to undo it.

Ok, I see it now, it took me awhile with my slow brain. And the code is
not a walk in the park anyway, thanks Thomas for pointing this out.

-- 
Regards/Gruss,
    Boris.
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