linux-kernel - Re: [Bug #12152] Huge wakeups number from i1915

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Message-Id: <200812080828.07683.rjw@sisk.pl>
Date:	Mon, 8 Dec 2008 08:28:07 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"Yves-Alexis Perez" <corsac@...ian.org>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Kernel Testers List <kernel-testers@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: [Bug #12152] Huge wakeups number from i1915

On Monday, 8 of December 2008, Yves-Alexis Perez wrote:
> On dim, 2008-12-07 at 15:12 -0800, Arjan van de Ven wrote:
> > 
> > > > at least in some of the cases where this has been seen the cause
> > is
> > > > the following:
> > > > The i915 DRM driver used to do polling for completion, busy
> > > > waiting. It moved to be interrupt driven, which is usually better
> > > > for power, but it will show up as more wakeups in powertop....
> > > 
> > > IOW, this is not a regression?
> > 
> > I don't know about this specifc case (not enough information) but for
> > the case I described it's not a regression. Going to interrupt driven
> > from busy waiting is an improvement not a regression :)
> 
> Well, several thousand or more interrupts really seems like a
> regression :). But it seems that's the same thing as the “IRQ
> spinning” (there was a thread on dri-devel about that).
> 
> It seems fixed with a patch from Matthew Garrett applied to
> drm-intel/for-airlied but I don't think this has been applied to Linus
> master.

Any pointers to the patch, please?

Rafael
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