Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964905AbWIDNJx (ORCPT ); Mon, 4 Sep 2006 09:09:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964825AbWIDNJx (ORCPT ); Mon, 4 Sep 2006 09:09:53 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:36614 "EHLO spitz.ucw.cz") by vger.kernel.org with ESMTP id S964905AbWIDNJw (ORCPT ); Mon, 4 Sep 2006 09:09:52 -0400 Date: Mon, 4 Sep 2006 13:09:33 +0000 From: Pavel Machek To: Jim Gettys Cc: Bjorn Helgaas , Matthew Garrett , "Brown, Len" , Linux Kernel ML , Dominik Brodowski , ACPI ML , Adam Belay , "Pallipadi, Venkatesh" , Arjan van de Ven , devel@laptop.org Subject: Re: [OLPC-devel] Re: [RFC][PATCH 1/2] ACPI: Idle Processor PM Improvements Message-ID: <20060904130933.GC6279@ucw.cz> References: <20060830194317.GA9116@srcf.ucam.org> <200608311713.21618.bjorn.helgaas@hp.com> <1157070616.7974.232.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1157070616.7974.232.camel@localhost.localdomain> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1443 Lines: 32 Hi! > In short, we have novel hardware: we can have our screen on, and suspend > the processor to RAM, and use a half a watt. We can have our wireless > forwarding packets in our mesh networks, with the processor suspended, > consuming under 400mw (we hope 300mw by the time we ship). Both on, and > we're still under one watt. > > For keyboard activity, human perception is in the 100-200 millisecond > range; for some other stuff, it is even less much than that. So that's > the necessity; now the invention. > > I've done a straw pole among kernel gurus at OLS and elsewhere on how > fast Linux might be able to resume. I've gotten answers of typically > "one second". > > But, on other platforms (see attached), I have data I've measured myself > showing Linux going from resume from RAM to *scheduling user level > processes* 100 times faster than that, on a wimpy 200mhz ARM processor. > Yes, Matilda, Linux can, on non-braindead hardware, resume all the way > to scheduling user processes in 10 milliseconds on a 200mhz processor. 2.4 and 2.6 are *very* different here. You'll probably need to optimize freezer in 2.6 a bit... Pavel -- Thanks for all the (sleeping) penguins. - 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/