From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH 11/11] drm/i915: add HAS_ALIASING_PPGTT parameter for userspace Date: Tue, 06 Dec 2011 18:31:14 +0000 Message-ID: References: <1322515495-13049-1-git-send-email-daniel.vetter@ffwll.ch> <1322515495-13049-4-git-send-email-daniel.vetter@ffwll.ch> <20111206173938.GA32563@bolo_yeung.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga03.intel.com (mga03.intel.com [143.182.124.21]) by gabe.freedesktop.org (Postfix) with ESMTP id 4A14B9E777 for ; Tue, 6 Dec 2011 10:33:10 -0800 (PST) In-Reply-To: <20111206173938.GA32563@bolo_yeung.jf.intel.com> 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: Ben Widawsky , Daniel Vetter Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Tue, 6 Dec 2011 09:39:39 -0800, Ben Widawsky wrote: > On Mon, Nov 28, 2011 at 10:24:55PM +0100, Daniel Vetter wrote: > > On Sanybridge a few MI read/write commands only work when ppgtt is > > enabled. Userspace therefore needs to be able to check whether ppgtt > > is enabled. For added hilarity, you need to reset the "use global GTT" > > bit on both snb/ivb when ppgtt is enabled, otherwise it won't work. > > Despite what bspec says about automatically using ppgtt ... > > > > Luckily PIPE_CONTROL (the only write cmd current userspace uses) is > > not affected by all this, as tested by tests/gem_pipe_control_store_loop. > > Since this is all SNB only, and we have no good benchmarks to show > performance gains, can we not just enable this for IVB+? Don't we have the same basic problem with IVB, that we need to adjust the commands in the batchbuffer depending on whether HAS_ALIASING_PPGTT is true? Or do you mean that we should just assume that IVB uses the ppgtt and so kernel 3.3+, which will be around March... -Chris -- Chris Wilson, Intel Open Source Technology Centre