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From: Ben Widawsky <ben@bwidawsk.net>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>, Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Reduce locking in command submission
Date: Thu, 15 Jan 2015 08:54:03 -0800	[thread overview]
Message-ID: <20150115165402.GA8350@bwidawsk.net> (raw)
In-Reply-To: <1421320890-29713-1-git-send-email-tvrtko.ursulin@linux.intel.com>

On Thu, Jan 15, 2015 at 11:21:30AM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> 
> This eliminates six needless spin lock/unlock pairs when writing out ELSP. Apart
> from tidier code main benefit is between 0.51% and 0.73% speedup on some OGL
> tests under CHV (bench_OglBatch4 bench_OglDeferred respectively).

With 95% confidence t-test on n=5

> 
> Kindly benchmarked by Ben Widawsky.

FWIW, as I mentioned on IRC, I think the reduction of the unnecessary forcewake
(someone should fix the shadow register list) is probably more beneficial than
removing the spin on an uncontested lock. I was tempted to try that myself, but
I didn't have time or much interest since your patch accomplishes the same
thing.

The sucky thing, which I actually care about since I've been doing a lot of
profiling, is the raw MMIO doesn't show up with our i915 trace functions. It's
obtainable still, but then I get a mess of other stuff I don't want.

> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Dave Gordon <david.s.gordon@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Ben Widawsky <ben@bwidawsk.net>
[snip]

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  reply	other threads:[~2015-01-15 16:54 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-11 15:41 [RFC] drm/i915: Reduce locking in command submission Tvrtko Ursulin
2014-12-15 13:06 ` Daniel Vetter
2014-12-16 13:34   ` Tvrtko Ursulin
2015-01-14 10:13   ` Tvrtko Ursulin
2015-01-15 11:21 ` [PATCH] " Tvrtko Ursulin
2015-01-15 16:54   ` Ben Widawsky [this message]
2015-01-15 17:05     ` Tvrtko Ursulin
2015-01-15 23:42       ` Ben Widawsky
2015-01-16  0:19   ` shuang.he

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