From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261335AbVHFOy2 (ORCPT ); Sat, 6 Aug 2005 10:54:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261979AbVHFOy2 (ORCPT ); Sat, 6 Aug 2005 10:54:28 -0400 Received: from THUNK.ORG ([69.25.196.29]:28851 "EHLO thunker.thunk.org") by vger.kernel.org with ESMTP id S261335AbVHFOy0 (ORCPT ); Sat, 6 Aug 2005 10:54:26 -0400 Date: Sat, 6 Aug 2005 10:54:18 -0400 From: "Theodore Ts'o" To: Con Kolivas Cc: linux-kernel@vger.kernel.org, tony@atomide.com, tuukka.tikkanen@elektrobit.com, ck@vds.kolivas.org Subject: Re: [patch] i386 dynamic ticks 2.6.13-rc4 (code reordered) Message-ID: <20050806145418.GA16523@thunk.org> Mail-Followup-To: Theodore Ts'o , Con Kolivas , linux-kernel@vger.kernel.org, tony@atomide.com, tuukka.tikkanen@elektrobit.com, ck@vds.kolivas.org References: <200508021443.55429.kernel@kolivas.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200508021443.55429.kernel@kolivas.org> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 02, 2005 at 02:43:55PM +1000, Con Kolivas wrote: > This is a code reordered version of the dynamic ticks patch from Tony Lindgen > and Tuukka Tikkanen - sorry about spamming your mail boxes with this, but > thanks for the code. There is significant renewed interest by the lkml > audience for such a feature which is why I'm butchering your code (sorry > again if you don't like me doing this). The only real difference between your > code and this patch is moving the #ifdef'd code out of code paths and putting > it into dyn-tick specific files. > > This has slightly more build fixes than the last one I posted and boots and > runs fine on my laptop. So far at absolute idle it appears this pentiumM 1.7 > is claiming to have _25%_ more battery life. I'll need to investigate further > to see the real power savings. Hi Con, I had a chance to try out your patch (2.6.13-rc4-dtck-2.patch) and using either the APIC or PIT timer, if dynamic tick is enabled, on my laptop, this kicks up the bus mastering activity enough so that the processor doesn't have a chance to enter the C4 state, and stays stuck at C2. As a result, enabling dynamic tick _increases_ power consumption by 20% on my T40 laptop (1.6 MHz Pentium M). I monitored power utilization using pmstats-0.2, and used /proc/acpi/processor/CPU/power to monitor bus mastering activity and the CPU C-states. As soon as I disabled dynamic tick using: echo 0 > /sys/devices/system/timer/timer0/dyn_tick_state The number of ticks went up to 1024, bus mastering activity dropped to zero, and the processor entered C4 state, and power utilization dropped by 20%. When I enabled dynamic tick using: echo 1 > /sys/devices/system/timer/timer0/dyn_tick_state The number of ticks dropped down to 60-70 HZ, bus mastering activity jumpped up to being almost always active, and the processor stayed stuck at C2 state, and power utilization climbed back up by 20%. This was on a completely idle, freshly booted machine, without X running and just a console login. - Ted