[Intel-gfx] [PATCH 1/2] drm/i915: re-enable semaphores by default

[Andrew Lutomirski]

On Wed, Nov 16, 2011 at 9:16 AM, Keith Packard <keithp at keithp.com> wrote:
> On Wed, 16 Nov 2011 16:49:40 +0100, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
>
>> So we need to check whether DMAR is enabled (on the
>> entire system, i.e. the variable exported for the ilk workaround is
>> not good enough)
>
> Can you figure out what *would* be sufficient? Getting semaphores turned
> on for the 99% who aren't enabling VT-d would be a fairly nice
> performance improvement.

AFAICT my snb laptop has always been stable with semaphores and VT-d
enabled.  Is this problem possibly restricted to just desktop
machines?  I'm happy to test, since my box that can reproduce the hang
instantly is still around.

Also, rc6-by-default would be very nice.  It decreases the total power
consumption on my laptop from over 13W to around 8W.  That's huge.

--Andy