[Intel-gfx] [PATCH] drm/i915: [GEN7] Use HW scheduler for fixed function shaders

Eugeni Dodonov eugeni at dodonov.net
Sun Apr 15 16:55:36 CEST 2012

On Sat, Apr 14, 2012 at 22:41, Ben Widawsky <ben at bwidawsk.net> wrote:

> This originally started as a patch from Bernard as a way of simply
> setting the VS scheduler. After submitting the RFC patch, we decided to
> also modify the DS scheduler. To be most explicit, I've made the patch
> explicitly set all scheduler modes, and included the defines for other
> modes (in case someone feels frisky later).
> The rest of the story gets a bit weird. The first version of the patch
> showed an almost unbelievable performance improvement. Since rebasing my
> branch it appears the performance improvement has gone, unfortunately.
> But setting these bits seem to be the right thing to do given that the
> docs describe corruption that can occur with the default settings.
> In summary, I am seeing no more perf improvements (or regressions) in my
> limited testing, but we believe this should be set to prevent rendering
> corruption, therefore cc stable.
> v1: Clear bit 4 also (Ken + Eugeni)
> Do a full clear + set of the bits we want (Me).
> Cc: Bernard Kilarski <bernard.r.kilarski at intel.com>
> Cc: stable <stable at vger.kernel.org>
> Reviewed-by (RFC): Kenneth Graunke <kenneth at whitecape.org>
> Signed-off-by: Ben Widawsky <benjamin.widawsky at intel.com>

Very nice!

I also suspect that maybe the initial performance improvement you've seen
with previous testing could be related to the occasional turbo disabling
we've been seeing in other cases as well (e.g.,

But as for this patch, I have just one comment/suggestion below, but other
than that:

Reviewed-by: Eugeni Dodonov <eugeni.dodonov at intel.com>

+static void gen7_setup_fixed_func_scheduler(struct drm_i915_private
> *dev_priv)

Perhaps this functions should be named ivybridge_setup_fixed_func_scheduler

Even if those bits are not ivy bridge-exclusive, this specific explicit
setup applies to ivb only..

Eugeni Dodonov
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