From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: Re: p4-clockmod doesn't seem to allow the highest possible speed Date: Sun, 11 Jan 2004 21:06:18 +0100 Sender: cpufreq-bounces@www.linux.org.uk Message-ID: <20040111200617.GA25713@dominikbrodowski.de> References: <20040110101534.GA10003@dominikbrodowski.de> <20040110110800.GA8294@grep.be> <20040110131824.GA5010@dominikbrodowski.de> <20040110152145.GA10160@grep.be> <20040110154110.GA8735@dominikbrodowski.de> <20040110163212.GD10531@grep.be> <20040110185308.GZ14031@poupinou.org> <20040110193526.GM10531@grep.be> <20040111173547.GB5485@dominikbrodowski.de> <20040111195619.GA25048@grep.be> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============44678247972321161==" Return-path: In-Reply-To: <20040111195619.GA25048@grep.be> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: cpufreq-bounces@www.linux.org.uk To: Wouter Verhelst Cc: Ducrot Bruno , cpufreq@www.linux.org.uk --===============44678247972321161== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="9jxsPFA5p3P2qPhR" Content-Disposition: inline --9jxsPFA5p3P2qPhR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Jan 11, 2004 at 08:56:19PM +0100, Wouter Verhelst wrote: > On Sun, Jan 11, 2004 at 06:35:47PM +0100, Dominik Brodowski wrote: > > On Sat, Jan 10, 2004 at 08:35:26PM +0100, Wouter Verhelst wrote: > > > That happens both when it's in P0 or P1. > >=20 > > So ACPI works to set the processor in P0 and P1? >=20 > Yes. Excellent. >=20 > > If so, you really really should use the ACPI cpufreq driver instead of > > the p4-clockmod driver. The former will offer you true "SpeedStep" > > support, the latter only some clock modulation which won't save you > > much energy as ACPI supports the C2 idle state anyway.=20 >=20 > Ah, so what p4-clockmod does is not SpeedStep? >=20 > Hm. That sucks. No. p4-clockmod stops the CPU for certain short periods of time, it "modulates" the CPU frequency.=20 ------------------> time axis x x x x x x x x x normal clock ticks x x x x - - - - x 50 % frequency modulation [ACPI T-States or P4-clockmod] x x x x x x frequency scaling [ACPI P-States] Only if the frequency is scaled, the voltage can be scaled also. So only that offers the best reduction of energy usage. For details, check the cpufreq archives for a lengthy thread with many calculations... > > > Not that it matters -- p4-clockmod seems to do it right :) > >=20 > > It's not as noisy, indeed. But it's not right -- as long as acpi.ko wor= ks. >=20 > It mostly does, although I've had lockups when using the /proc interface > to switch CPU frequencies -- yes, should've reported that, but I only > now remember :) The /proc/ interface is deprecated, and the acpi module is full of errors [I'm working on it, though...]. You should use the /sys-fs interface with the acpi.ko module as well. > That does not change. Very strange... I'm out of ideas for the moment being. Dominik --9jxsPFA5p3P2qPhR Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) iD8DBQFAAay5Z8MDCHJbN8YRAho5AKCDDZh8RdJts9Cab4d3DHu+GiO+bgCfULwD 4/5LqBZHowP/jwiRRTLq3/s= =gbkE -----END PGP SIGNATURE----- --9jxsPFA5p3P2qPhR-- --===============44678247972321161== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Cpufreq mailing list Cpufreq@www.linux.org.uk http://www.linux.org.uk/mailman/listinfo/cpufreq --===============44678247972321161==--