linux-kernel - Re: [PATCH 2/2] cpuidle: Add a repeating pattern detector to the menu governor

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Message-Id: <20100510194329.f49eeb96.akpm@linux-foundation.org>
Date:	Mon, 10 May 2010 19:43:29 -0400
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] cpuidle: Add a repeating pattern detector to the
 menu governor

On Mon, 10 May 2010 18:27:46 -0700 Arjan van de Ven <arjan@...radead.org> wrote:

> On Mon, 10 May 2010 14:38:50 -0700
> Andrew Morton <akpm@...ux-foundation.org> wrote:
> 
> > > +	if (avg && stddev < STDDEV_THRESH)
> > > +		data->predicted_us = avg;
> > > +}
> > 
> > You got lucky there, because INTERVALS is a power of two.  If someone
> > changes INTERVALS to 7, this code will ask for __udivdi3 and won't
> > link on i364.
> 
> yeah you'd think it almost isn't an accident ;-)

If it was deliberate the code would read

	avg >>= INTERVALS_SHIFT;

:-p
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