Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262451AbUJ0Onf (ORCPT ); Wed, 27 Oct 2004 10:43:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262462AbUJ0Onf (ORCPT ); Wed, 27 Oct 2004 10:43:35 -0400 Received: from fmr01.intel.com ([192.55.52.18]:30939 "EHLO hermes.fm.intel.com") by vger.kernel.org with ESMTP id S262451AbUJ0Onc convert rfc822-to-8bit (ORCPT ); Wed, 27 Oct 2004 10:43:32 -0400 X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: [PATCH] Add p4-clockmod driver in x86-64 Date: Wed, 27 Oct 2004 07:43:16 -0700 Message-ID: <88056F38E9E48644A0F562A38C64FB600333A69D@scsmsx403.amr.corp.intel.com> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [PATCH] Add p4-clockmod driver in x86-64 Thread-Index: AcS70+S7aN+OwZnRR6CCs/fmzK5cnAAWhFYg From: "Pallipadi, Venkatesh" To: "Andi Kleen" Cc: , X-OriginalArrivalTime: 27 Oct 2004 14:43:18.0002 (UTC) FILETIME=[4C245520:01C4BC33] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1618 Lines: 48 >-----Original Message----- >From: Andi Kleen [mailto:ak@suse.de] >Sent: Tuesday, October 26, 2004 8:18 PM >To: Pallipadi, Venkatesh >Cc: akpm@osdl.org; ak@suse.de; linux-kernel@vger.kernel.org >Subject: Re: [PATCH] Add p4-clockmod driver in x86-64 > >On Tue, Oct 26, 2004 at 02:28:26PM -0700, Venkatesh Pallipadi wrote: >> >> Add links for p4-clockmod driver in x86-64 cpufreq. > >Does this really make sense? I thought all shipping EM64T capable CPUs >supported DBS? Why would you want clock modulation when you have DBS? > >My own experience is that the clockmod driver is not very usable, >it leads to extensive delays on a graphical desktop. > Yes. Clock modulation is not as useful compared to enhanced speedstep. But, I feel, it should be OK to have the driver, though it is not really useful in common case. It may be useful in some exceptional cases. The particular case where someone wanted to use p4-clockmod was: they wanted to run the CPU as slow as possible. Enhanced speedstep allows few (2-3) possible freqs on this CPU. But, p4-clockmod allows as low as 12.5% actual freq. So, I think, it is good to have this module for the users who really want to use it. But I don't think any userspace or kernel governor should use this driver by default, without user knowledge. That can cause extensive delays and slow response times. Thanks, Venki - 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/