From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932155AbVLZX1x (ORCPT ); Mon, 26 Dec 2005 18:27:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932156AbVLZX1x (ORCPT ); Mon, 26 Dec 2005 18:27:53 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:39329 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S932155AbVLZX1x (ORCPT ); Mon, 26 Dec 2005 18:27:53 -0500 Date: Tue, 27 Dec 2005 00:27:12 +0100 From: Pavel Machek To: "Theodore Ts'o" , Con Kolivas , linux kernel mailing list , Dominik Brodowski , Daniel Petrini , Tony Lindgren , vatsa@in.ibm.com, ck list , Adam Belay , Zwane Mwaikambo Subject: Re: [PATCH] i386 No Idle HZ aka dynticks 051221 Message-ID: <20051226232712.GH1974@elf.ucw.cz> References: <200512210310.51084.kernel@kolivas.org> <20051225171617.GA6929@thunk.org> <20051226025525.GA6697@thunk.org> <20051226203806.GC1974@elf.ucw.cz> <20051226225246.GA9915@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051226225246.GA9915@thunk.org> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Po 26-12-05 17:52:48, Theodore Ts'o wrote: > On Mon, Dec 26, 2005 at 09:38:06PM +0100, Pavel Machek wrote: > > Stupid IBM. I've seen it appearing/disappearing, but did not work out > > when. > > > > No-C4-on-AC is bad -- if you just disconnect AC and walk away, you are > > running without benefits of C4. Bad. Changing benchmarks depending on > > you booting on AC or battery also look nasty. > > The moment you disconnect AC, it C4 automagically appears. When you > reconnect to the AC mains, the C4 state disappears again, at least > from the listing displayed by /proc/acpi/processor/CPU0/power. So the > first issue you brought up isn't a problem. It does not seem to work like that here. I'm not sure what the exact rules are, but I know that I sometimes have C4 and sometimes not. I have C4 now, and it is used, even when I'm on AC power. Thinkpad X32. > More of an issue is that there are times when the laptop might think > that it's running of the AC mains, but in fact the owner may have > connected an external battery, and might _want_ the system to be as > frugal as possible with the power. Yes... OTOH it is not that bad -- we could simply hardcode data from acpi BIOS into kernel, ignore what ACPI says, and drive C4 even on AC power. But that would be hack (tm). > Whether I boot from AC power battery seems to be immaterial; what > seems to matter is whether or not the laptop is running on battery at > the moment that /proc/acpi/processor/CPU0/power is sampled. I did not realize ACPI was _that_ clever. Anyway, it is different on my machine... Pavel -- Thanks, Sharp!