From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: Re: cpufreq doesn't seem to work in Intel Q9300 Date: Mon, 11 Aug 2008 21:33:17 +0200 Message-ID: <20080811193316.GA16631@isilmar.linta.de> References: <514e099a0808030300u140a0ae7m92a2e7294f39f7b7@mail.gmail.com> <200808081430.43012.trenn@suse.de> <200808092059.47863.trenn@suse.de> <514e099a0808100128u303207clcb22292db2f0cc59@mail.gmail.com> <1218418431.6671.52.camel@yakui_zhao.sh.intel.com> <514e099a0808102144n241c8e9ak255bded0a80744f1@mail.gmail.com> <20080811042244.469f8e1d@infradead.org> <20080811140206.GB3338@cs181140183.pp.htv.fi> <20080811071128.0165be50@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from isilmar.linta.de ([213.133.102.198]:39842 "EHLO linta.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753583AbYHKTdT (ORCPT ); Mon, 11 Aug 2008 15:33:19 -0400 Content-Disposition: inline In-Reply-To: <20080811071128.0165be50@infradead.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Arjan van de Ven Cc: Adrian Bunk , S K , Zhao Yakui , Thomas Renninger , Alan Jenkins , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org Hi, On Mon, Aug 11, 2008 at 07:11:28AM -0700, Arjan van de Ven wrote: > 1) when the cpu is idle (as in "idle loop C states/hlt"; p4_clockmod > doesn't mean anything.. the clock is stopped not just skipped. > 2) when the cpu is executing code (eg non-idle), it takes more power > for a unit of time than it takes when it's idle This statement might be true, but might also be wrong: a) on systems where only C1 is exported, p4-clockmod most often equals the state the CPU is in when in C1[*], so we're in a win-win, or lose-lose situation. b) IIRC 50% throttling is not "execute-one-statement skip-one-statement execute-one-statement, etc." but instead work for N us, skip for N us, work for N us, etc. Therefore, the situation is a bit more compilcated. Still, I agree that p4-clockmod is useful mostly in corner cases (and for developing the cpufreq infrastructure in the first case, but that's another story) [*] or C2 even? Best, Dominik