linux-kernel - Re: Slow down stupid pounders

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Message-ID: <20140614203220.GB3853@xo-6d-61-c0.localdomain>
Date:	Sat, 14 Jun 2014 22:32:20 +0200
From:	Pavel Machek <pavel@....cz>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Mike Galbraith <mgalbraith@...e.de>,
	lkml <linux-kernel@...r.kernel.org>, x86-ml <x86@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Mel Gorman <mgorman@...e.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: Slow down stupid pounders

On Tue 2014-05-06 18:10:04, Borislav Petkov wrote:
> On Tue, May 06, 2014 at 05:08:19PM +0200, Mike Galbraith wrote:
> > Rather than ratelimit the interface perhaps send a ratelimited note
> > telling the user straight up that he's begging for trouble. We can
> > ignore it when regression testing, and point it out to Joe Pounder
> > should he fail to notice.. or be somewhat dense.
> 
> Yeah, if those dudes don't stare at dmesg, that note doesn't bring us
> whit.
> 
> Alternatively, we could do
> 
> 	add_taint(TAINT_HOTPLUG_POUNDER)
> 
> when the rate is exceeded...
> 
> I'd rather like to slow it down for a second, though, if it doesn't hurt
> any sensible use cases in doing so.

Actually, you should just taint as soon as someone tries to use cpu hotplug if 
it does not work. 

I wonder what happens on those multi-core android phones. They suspend multiple 
times a second. Do they do cpu hotplugs at that point?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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