Re: [PATCH] drm/i915: initialize ring frequency scaling table on SNB

[Chris Wilson <chris@chris-wilson.co.uk>]

On Tue, 21 Jun 2011 15:24:24 -0700, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> The ring frequency scaling table tells the PCU to treat certain GPU
> frequencies as if they were a given CPU frequency for purposes of
> scaling the ring frequency.  Normally the PCU will scale the ring
> frequency based on the CPU P-state, but with the table present, it will
> also take the GPU frequency into account.  The scaling_factor used in
> this patch may not be ideal, but is enough to increase performance in
> nexuiz on a 1366x768 panel by about 20%.

Am I right in thinking that the improvement offered by these new defaults
is dependent upon the previous values programmed by the BIOS? On my
desktop SNB, I only see a marginal improvement (<~1%) for games and
similarly small differences for cairo-gl/xlib.

Plus they also revealed my confusion over dev_priv->min_delay is actually
min_freq on SNB. Evil. :-p
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre