From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] drm/i915: Lazily apply the SNB+ seqno w/a Date: Fri, 10 Aug 2012 11:38:06 +0200 Message-ID: <20120810093800.GA5738@phenom.ffwll.local> References: <1344503896-18093-1-git-send-email-chris@chris-wilson.co.uk> <1344506310-18191-1-git-send-email-chris@chris-wilson.co.uk> <20120809102916.GB5367@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com [209.85.212.177]) by gabe.freedesktop.org (Postfix) with ESMTP id 417409F2F9 for ; Fri, 10 Aug 2012 02:37:49 -0700 (PDT) Received: by wibhn17 with SMTP id hn17so202919wib.12 for ; Fri, 10 Aug 2012 02:37:48 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20120809102916.GB5367@phenom.ffwll.local> 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: Chris Wilson Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Thu, Aug 09, 2012 at 12:29:16PM +0200, Daniel Vetter wrote: > On Thu, Aug 09, 2012 at 10:58:30AM +0100, Chris Wilson wrote: > > Avoid the forcewake overhead when simply retiring requests, as often the > > last seen seqno is good enough to satisfy the retirment process and will > > be promptly re-run in any case. Only ensure that we force the coherent > > seqno read when we are explicitly waiting upon a completion event to be > > sure that none go missing, and also for when we are reporting seqno > > values in case of error or debugging. > > > > This greatly reduces the load for userspace using the busy-ioctl to > > track active buffers, for instance halving the CPU used by X in pushing > > the pixels from a software render (flash). The effect will be even more > > magnified with userptr and so providing a zero-copy upload path in that > > instance, or in similar instances where X is simply compositing DRI > > buffers. > > > > v2: Reverse the polarity of the tachyon stream. Daniel suggested that > > 'force' was too generic for the parameter name and that 'lazy_coherency' > > better encapsulated the semantics of it being an optimization and its > > purpose. Also notice that gen6_get_seqno() is only used by gen6/7 > > chipsets and so the test for IS_GEN6 || IS_GEN7 is redundant in that > > function. > > > > Signed-off-by: Chris Wilson > > Yeah, I like the new color. > > Reviewed-by: Daniel Vetter > > I'll muse over this some more before picking it up, just in case I'll > notice a place this could blow up ... Ok, slurped into dinq, thanks for the patch. -Daniel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48