From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keith Packard Subject: Re: [PATCH] [RFC] drm/i915: read-read semaphore optimization Date: Tue, 13 Dec 2011 15:22:40 -0800 Message-ID: <868vmghxa7.fsf@sumi.keithp.com> References: <1323748328-10153-1-git-send-email-ben@bwidawsk.net> <20111213160133.GA4125@phenom.ffwll.local> <86k460ig3j.fsf@sumi.keithp.com> <4EE7D68D.1090803@bwidawsk.net> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0068049779==" Return-path: Received: from keithp.com (home.keithp.com [63.227.221.253]) by gabe.freedesktop.org (Postfix) with ESMTP id C711A9E778 for ; Tue, 13 Dec 2011 15:21:51 -0800 (PST) In-Reply-To: <4EE7D68D.1090803@bwidawsk.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: Ben Widawsky Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org --===============0068049779== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" --=-=-= Content-Transfer-Encoding: quoted-printable On Tue, 13 Dec 2011 14:49:49 -0800, Ben Widawsky wrote: > Would we want to keep domain tracking if the HW worked correctly and we > didn't have to always flush. It seems like a shame to just gut the code > if it actually could offer a benefit on future generations. That sounds like premature optimization to me. If we want something similar on future hardware, we can resurrect the old code and see what pieces are useful. For now, we're fighting correctness and stability issues, and given the limited (zero? negative?) performance benefits, we just need to get to code which works reliably and provides good performance. The current code has gotten to the 'piles of kludges on kludges' stage, which makes it very fragile -- see the regression caused by changing flushing orders in the VT-d work-around. =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIVAwUBTufeQDYtFsjWk68qAQgnmg//Q+Dmk5+K/UnE9HrLSRy/wl7SHe/TkTUh 4XV0wFoOEa9Heii4sywVIf5/qcAybcHwgyjgE5t0jwOwI4zGyVSdGzpjukYqvExM 3jOTlyPVQ6Wn5kzIFTKEXVHv7fHJsp2NzxxQLalsFGCNenTLLK5jm7pueCEKJcyR R9SOWoCxjsFpyjqGlFZBAiazhHZNqAdcK27cc5T2jQImLhtykLuvFJcZLZKowRI6 fL8VLfEj94eYxX5f/Baot2UqdtDVIbvyF/pfYNVqKnhiwr+lyCwMYzOk9x1XVeC2 iTQ50JQIbBlx8ng9DbsrChFFRS0fcPmEVT71G5C7ITJ/HFcAuqaX8jrVcgTKLdx4 j4/NWhfmy+brlfUk5fw2NIh11v/NstGPuwgjH4JcEX1HW1tKFdeL/u69ob8g8heJ nPgNVPMdh42ikgp2hsumSDNO+KjMaJRaEd/qHL6w81Eu28reEhNlltFFlqPNcMtm Jyw13XOp1GJEKIZT5YAfmA8ZuXFlgAB4ZiHbQKMp6x4iBxlfFBvIIM5Yy2/AY6qM wXkaTT5olm+kksE/I3+CiwzEItmw7E9iGBNR/WAXWDk3J2+b6g7Q5YYRtsYNqB0v 1izvGnSLUIWXfStiPAQsRuzQ/JGsiOaMP2QBHPqOmxm1eBTf1QniCjW4bO1GZPd1 wWhHOAqS9eY= =TLxK -----END PGP SIGNATURE----- --=-=-=-- --===============0068049779== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx --===============0068049779==--