From mboxrd@z Thu Jan 1 00:00:00 1970 From: Len Brown Subject: Re: [OLPC-devel] Re: [RFC][PATCH 1/2] ACPI: Idle Processor PM Improvements Date: Thu, 31 Aug 2006 23:53:04 -0400 Message-ID: <200608312353.05337.len.brown@intel.com> References: <200608311713.21618.bjorn.helgaas@hp.com> <1157070616.7974.232.camel@localhost.localdomain> Reply-To: Len Brown Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:10689 "EHLO hera.kernel.org") by vger.kernel.org with ESMTP id S1750967AbWIADwF (ORCPT ); Thu, 31 Aug 2006 23:52:05 -0400 In-Reply-To: <1157070616.7974.232.camel@localhost.localdomain> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: jg@laptop.org Cc: Bjorn Helgaas , Matthew Garrett , Linux Kernel ML , Dominik Brodowski , ACPI ML , Adam Belay , "Pallipadi, Venkatesh" , Arjan van de Ven , devel@laptop.org On Thursday 31 August 2006 20:30, Jim Gettys wrote: > On Thu, 2006-08-31 at 17:13 -0600, Bjorn Helgaas wrote: > > On Wednesday 30 August 2006 13:43, Matthew Garrett wrote: > > > That would be helpful. For the One Laptop Per Child project (or whatever > > > it's called today), it would be advantageous to run without acpi. > > > > Out of curiosity, what is the motivation for running without acpi? > > It costs a lot to diverge from the mainstream in areas like that, > > so there must be a big payoff. But maybe if OLPC depends on acpi > > being smarter about power or code size or whatever, those improvements > > could be made and everybody would benefit. > > Good question; I see Matthew beat me to part of the explanation, but > here is more detail: I recommended that the OLPC guys not use ACPI. I do not think it would benefit their system. Although it is an i386 instruction set, their system is more like an embedded device than like a traditional laptop. The Geode doesn't suport any C-states -- so ACPI wouldn't help them there anyway. As Jim wrote, OLPC plans to suspend-to-ram from idle, and to keep video running, so ACPI wouldn't help them on that either. Re: optimizing suspend/resume speed I expect suspend/resume speed has more to do with devices than with ACPI. But frankly, with gaping functionality holes in Linux suspend/resume support such as IDE and SATA, I think that optimizing for suspend/resume speed on a mainstream laptop is somewhat "forward looking". -Len