From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH] Revert "drm/i915: Kill GTT mappings when moving from GTT domain" Date: Sun, 19 Jun 2011 18:14:11 +0100 Message-ID: References: <1308094989-3153-1-git-send-email-eric@anholt.net> <87tybrcet0.fsf@eliezer.anholt.net> <87mxhg5lbl.fsf@eliezer.anholt.net> <87liwyao3u.fsf@eliezer.anholt.net> <013811$h7gjb@fmsmga002.fm.intel.com> <87y60xpxgc.fsf@eliezer.anholt.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com (mga14.intel.com [143.182.124.37]) by gabe.freedesktop.org (Postfix) with ESMTP id E4DD99F0BC for ; Sun, 19 Jun 2011 10:14:15 -0700 (PDT) In-Reply-To: <87y60xpxgc.fsf@eliezer.anholt.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Eric Anholt , intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Sun, 19 Jun 2011 10:01:23 -0700, Eric Anholt wrote: > On Sun, 19 Jun 2011 17:28:11 +0100, Chris Wilson wrote: > > For lack of a better mechanism. Even using anholt/gtt-revert, I question > > the value of caching the GTT mapping in drm_intel_bo. For the cairo-gl and > > pts benchmarks I've run, the efficacy of the cached vma is very small and > > there is a very slight improvement by unmapping the vma after use. (The > > difference is so small, that it will take a lot more runs to determine if > > it is statistically significant.) > > I'm confused. You've measured a 5% impact from removing this part of > the caching, and I've measured 12-19%, so what are you planning that > doesn't involve caching the mapping that's faster than caching the > mapping? As I pointed out, cairo-gl is using fallback code and not spans. Once that is corrected, cairo-gl no longer continually recreating textures and so unaffected by the patch. Removing the cached vma is then arguably beneficial, though the difference looks to be in the noise. -Chris -- Chris Wilson, Intel Open Source Technology Centre