From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: + restore-missing-sysfs-max_cstate-attr.patch added to -mm tree Date: Sat, 05 Jan 2008 11:27:21 -0500 Message-ID: <477FAFE9.6090809@rtr.ca> References: <20071130142058.816d1693.akpm@linux-foundation.org> <924EFEDD5F540B4284297C4DC59F3DEE2FAEAF@orsmsx423.amr.corp.intel.com> <4750CC78.9070105@rtr.ca> <20071130190227.1976e682@laptopd505.fenrus.org> <4750D180.6080001@rtr.ca> <20071130191816.3e744205@laptopd505.fenrus.org> <4750D585.1030200@rtr.ca> <477C2143.8090406@rtr.ca> <924EFEDD5F540B4284297C4DC59F3DEE4FC485@orsmsx423.amr.corp.intel.com> <477C622F.6010304@rtr.ca> <20080104021619.GA15409@linux-os.sc.intel.com> <477DA529.4000500@rtr.ca> <477EAAB0.1000101@rtr.ca> <924EFEDD5F540B4284297C4DC59F3DEE4FCC51@orsmsx423.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([76.10.145.34]:1203 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753907AbYAEQ1Y (ORCPT ); Sat, 5 Jan 2008 11:27:24 -0500 In-Reply-To: <924EFEDD5F540B4284297C4DC59F3DEE4FCC51@orsmsx423.amr.corp.intel.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Pallipadi, Venkatesh" Cc: Arjan van de Ven , Andrew Morton , abelay@novell.com, lenb@kernel.org, Ingo Molnar , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, rjw@sisk.pl Pallipadi, Venkatesh wrote: >> -----Original Message----- >> From: Mark Lord [mailto:lkml@rtr.ca] .. >> Okay, with !CONFIG_CPU_IDLE, this works fine -- same as 2.6.23 >> and earlier. >> > > Good to know. Atleast we do not have a regression for 2.6.24 now. .. Agreed. We're happy here, for now. >>> Meanwhile, can you give a short summary of how behaviour differs >>> between CONFIG_CPU_IDLE and !CONFIG_CPU_IDLE ?? >>> >>> I'm not at all clear on how this really affects things. > > With CPU_IDLE, the C-state policy is removed from acpi driver. Ideally > policy should have nothing to do with ACPI, as ACPI only provides the > C-state mechanisms. So, with CPU_IDLE, it is not easy to control this > variable through a acpi driver module at run time. Also, the latency > interface that was mentioned before is to serve the same purpose in a > more clear manner (based on the wakeup latency) instead of a C-state > number which may not mean much from the end user point of view. > > I will look at why latency does not work on a single core system > soon(Was that with UP kernel or SMP kernel?). That way we will have a > proper cover for this with CPU_IDLE in future. .. That was with a UP kernel on a UP box. The latency thingie really seemed to have little or no effect, whereas setting max_cstate=1 has a quite noticeable positive impact. Things seemed okay (with the latency thingie) on the SMP machine, but with two cores it is probably simply more forgiving. cheers