[Intel-gfx] [PATCH 1/2] drm/i915: add module parameter compiler hints

[Ted Phelps]

Ben Widawsky writes:
> On Wed, Jul 06, 2011 at 04:03:14PM -0700, Keith Packard wrote:
> > On Wed,  6 Jul 2011 15:14:52 -0700, Ben Widawsky <ben at bwidawsk.net> wrote:
> >
> > > -static int i915_modeset =3D -1;
> > > +static int i915_modeset __read_mostly =3D -1;
> >
> > What effect does this have? Performance? Code size? More warnings?
> 
> __read_mostly attempts to put variables in a cachelines to make it more
> SMP friendly. I'm not sure if there is a performance impact as a result,
> but made this patch based on feedback from Chris. I've seen no
> regressions on Nexuiz.

A link to an informative LKML discussion on this topic is here:

    http://lkml.org/lkml/2007/12/17/43

-Ted