Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751250AbVI2It7 (ORCPT ); Thu, 29 Sep 2005 04:49:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751290AbVI2It7 (ORCPT ); Thu, 29 Sep 2005 04:49:59 -0400 Received: from mail.parbin.co.uk ([213.162.111.43]:57480 "EHLO mail.parbin.co.uk") by vger.kernel.org with ESMTP id S1751250AbVI2It6 (ORCPT ); Thu, 29 Sep 2005 04:49:58 -0400 Date: Thu, 29 Sep 2005 09:47:24 +0100 From: Alexander Clouter To: LKML , cpufreq@lists.linux.org.uk Cc: Andrew Morton , Dave Jones , Blaisorblade , alex-kernel@digriz.org.uk Subject: [patch 1/1] cpufreq: documentation for 'ondemand' and 'conservative' Message-ID: <20050929084724.GD3169@inskipp.digriz.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="8TaQrIeukR7mmbKf" Content-Disposition: inline Organization: diGriz X-URL: http://www.digriz.org.uk/ User-Agent: Mutt/1.5.10i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5173 Lines: 126 --8TaQrIeukR7mmbKf Content-Type: multipart/mixed; boundary="Yb+qhiCg54lqZFXW" Content-Disposition: inline --Yb+qhiCg54lqZFXW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Added a more verbose entry for the 'ondemend' governor and an entry for the= =20 'conservative' governor to the documentation. Signed-off-by: Alexander Clouter --Yb+qhiCg54lqZFXW Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="02_ondemand-and-conservative-documentation.diff" Content-Transfer-Encoding: quoted-printable diff -r -u linux-2.6.13.orig/Documentation/cpu-freq/governors.txt linux-2.6= =2E13/Documentation/cpu-freq/governors.txt --- linux-2.6.13.orig/Documentation/cpu-freq/governors.txt 2005-09-23 15:25= :14.302954250 +0100 +++ linux-2.6.13/Documentation/cpu-freq/governors.txt 2005-09-23 15:36:09.8= 75925000 +0100 @@ -27,6 +27,7 @@ 2.2 Powersave 2.3 Userspace 2.4 Ondemand +2.5 Conservative =20 3. The Governor Interface in the CPUfreq Core =20 @@ -110,9 +111,64 @@ =20 The CPUfreq govenor "ondemand" sets the CPU depending on the current usage. To do this the CPU must have the capability to -switch the frequency very fast. - +switch the frequency very quickly. There are a number of sysfs file +accessible parameters: =20 +sampling_rate: measured in uS (10^-6 seconds), this is how often you +want the kernel to look at the CPU usage and to make decisions on +what to do about the frequency. Typically this is set to values of +around '10000' or more. + +show_sampling_rate_(min|max): the minimum and maximum sampling rates +available that you may set 'sampling_rate' to. + +up_threshold: defines what the average CPU usaged between the samplings +of 'sampling_rate' needs to be for the kernel to make a decision on +whether it should increase the frequency. For example when it is set +to its default value of '80' it means that between the checking +intervals the CPU needs to be on average more than 80% in use to then +decide that the CPU frequency needs to be increased. =20 + +sampling_down_factor: this parameter controls the rate that the CPU +makes a decision on when to decrease the frequency. When set to its +default value of '5' it means that at 1/5 the sampling_rate the kernel +makes a decision to lower the frequency. Five "lower rate" decisions +have to be made in a row before the CPU frequency is actually lower. +If set to '1' then the frequency decreases as quickly as it increases, +if set to '2' it decreases at half the rate of the increase. + +ignore_nice: this parameter takes a value of '0' or '1', when set to +'0' then all processes are counted towards towards the 'cpu +utilisation' value. When set to '1' (its default) then processes that +are run with a 'nice' value will not count (and thus be ignored) in +the overal usage calculation. This is useful if you are running a CPU +intensive calculation on your laptop that you do not care how long it +takes to complete as you can 'nice' it and prevent it from taking part +in the deciding process of whether to increase your CPU frequency. + + +2.5 Conservative +---------------- + +The CPUfreq governor "conservative", much like the "ondemand" +governor, sets the CPU depending on the current usage. It differs in +behaviour in that it gracefully increases and decreases the CPU speed +rather than jumping to max speed the moment there is any load on the +CPU. This behaviour more suitable in a battery powered environment. +The governor is tweaked in the same manner as the "ondemand" governor +through sysfs with the addition of: + +freq_step: this describes what percentage steps the cpu freq should be +increased and decreased smoothly by. By default the cpu frequency will +increase in 5% chunks of your maximum cpu frequency. You can change this +value to anywhere between 0 and 100 where '0' will effectively lock your +CPU at a speed regardless of its load whilst '100' will, in theory, make +it behave identically to the "ondemand" governor. + +down_threshold: same as the 'up_threshold' found for the "ondemand" +governor but for the opposite direction. For example when set to its +default value of '20' it means that if the CPU usage needs to be below +20% between samples to have the frequency decreased. =20 3. The Governor Interface in the CPUfreq Core =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --Yb+qhiCg54lqZFXW-- --8TaQrIeukR7mmbKf Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) iD8DBQFDO6ocNv5Ugh/sRBYRAla6AJ9nhfweyXmARco+vYd09y93fxOGxwCffGpY xZwoKeGLPDfqywt/7TubscE= =R8/S -----END PGP SIGNATURE----- --8TaQrIeukR7mmbKf-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/