From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH] drm/i915: optimize the shmem_pwrite slowpath handling Date: Thu, 15 Nov 2012 15:37:01 +0000 Message-ID: <453bf0$6g3v6k@azsmga001.ch.intel.com> References: <1352992849-11219-1-git-send-email-daniel.vetter@ffwll.ch> 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 96D739E837 for ; Thu, 15 Nov 2012 07:37:06 -0800 (PST) In-Reply-To: <1352992849-11219-1-git-send-email-daniel.vetter@ffwll.ch> 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: Intel Graphics Development Cc: Daniel Vetter List-Id: intel-gfx@lists.freedesktop.org On Thu, 15 Nov 2012 16:20:49 +0100, Daniel Vetter wrote: > Since we drop dev->struct_mutex when going through the slowpath, the > object might have been moved out of the cpu domain. Hence we need to > clflush the entire object to ensure that after the ioctl returns, > everything is coherent again (interwoven writes are ill-defined > anyway). > > But we only need to do this if we start in the cpu domain and the > object requires flushing for coherency. So don't do the flushing if > the object is coherent anyway or if we've done in-line clfushing > already. > > v2: i915_gem_clflush_object already checks whether the object is > coherent and if so, drops the flushing. Hence we don't need to check > that ourselves, simplifying the condition. > Getting clearer, certainly. How about reversing the order of the checks so that it reads as if (used-fast-path && fast-path-no-longer-valid) do_fixup()? -Chris -- Chris Wilson, Intel Open Source Technology Centre