From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Anholt Subject: Re: [PATCH] drm/i915: initialize ring frequency scaling table on SNB Date: Wed, 22 Jun 2011 11:42:04 -0700 Message-ID: <8762nxiu83.fsf@eliezer.anholt.net> References: <20110621152424.75f54a13@jbarnes-desktop> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0311442698==" Return-path: In-Reply-To: <20110621152424.75f54a13@jbarnes-desktop> 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: Jesse Barnes , intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org --===============0311442698== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" --=-=-= Content-Transfer-Encoding: quoted-printable On Tue, 21 Jun 2011 15:24:24 -0700, Jesse Barnes = wrote: > The ring frequency scaling table tells the PCU to treat certain GPU > frequencies as if they were a given CPU frequency for purposes of > scaling the ring frequency. Normally the PCU will scale the ring > frequency based on the CPU P-state, but with the table present, it will > also take the GPU frequency into account. The scaling_factor used in > this patch may not be ideal, but is enough to increase performance in > nexuiz on a 1366x768 panel by about 20%. >=20 > The main downside of keeping the ring frequency high while the CPU is > at a low frequency (or asleep altogether) is increased power > consumption. But then if you're keeping your GPU busy, you probably > want the extra performance. The intent of the patch sounds good, but it doesn't seem to be doing anything here (graphs below). If I run a "while true; do; done" loop to keep a CPU busy during measurement, though, OA gets a 15.9% +/- 0.6% win, and nexuiz around 20%. There are no complaints in dmesg. x /home/anholt/nexuiz-before + /home/anholt/nexuiz-after +--------------------------------------------------------------------------= -----+ | x + + x x = +| ||_|_______________________M____MA_____A_________________________|_________= | | +--------------------------------------------------------------------------= -----+ N Min Max Median Avg Stddev x 3 59.217461 59.775295 59.479322 59.490693 0.27909057 + 3 59.287311 59.893383 59.440451 59.540382 0.31515189 No difference proven at 95.0% confidence x /home/anholt/oa-before + /home/anholt/oa-after +--------------------------------------------------------------------------= -----+ |x x + + + x * += x| | |________________________|_________MA_______A______M__________|_______= _| | +--------------------------------------------------------------------------= -----+ N Min Max Median Avg Stddev x 5 184.2 187.2 186.3 185.72 1.3809417 + 5 185.4 187 185.7 186.04 0.71624018 No difference proven at 95.0% confidence x /home/anholt/taiji-before + /home/anholt/taiji-after +--------------------------------------------------------------------------= -----+ |x x + xx + x + ++ + = x| | |____________________________A___|______________A______M_|_____| = | +--------------------------------------------------------------------------= -----+ N Min Max Median Avg Stddev x 6 132.486 139.931 135.608 135.596 2.6966051 + 6 134.974 138.832 138.111 137.41183 1.434609 No difference proven at 95.0% confidence --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk4CN3wACgkQHUdvYGzw6vcskACglo1zpGlAsqxmqWMHsxpGGpP5 WHUAniHWJwTEKO05DZSNvwfqJeGf0P0c =vUAe -----END PGP SIGNATURE----- --=-=-=-- --===============0311442698== 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 --===============0311442698==--