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: Wed, 02 Jan 2008 23:18:55 -0500 Message-ID: <477C622F.6010304@rtr.ca> References: <200711302153.lAULrZ7n026255@imap1.linux-foundation.org> <924EFEDD5F540B4284297C4DC59F3DEE2FAE6A@orsmsx423.amr.corp.intel.com> <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> 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]:4273 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752108AbYACES4 (ORCPT ); Wed, 2 Jan 2008 23:18:56 -0500 In-Reply-To: <924EFEDD5F540B4284297C4DC59F3DEE4FC485@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 Pallipadi, Venkatesh wrote: > > >> -----Original Message----- >> From: Mark Lord [mailto:lkml@rtr.ca] >> Sent: Wednesday, January 02, 2008 3:42 PM >> To: Arjan van de Ven >> Cc: Pallipadi, Venkatesh; Andrew Morton; abelay@novell.com; >> lenb@kernel.org; Ingo Molnar; linux-kernel@vger.kernel.org; >> linux-acpi@vger.kernel.org >> Subject: Re: + restore-missing-sysfs-max_cstate-attr.patch >> added to -mm tree >> >> Arjan van de Ven wrote: >>> On Fri, 30 Nov 2007 22:31:17 -0500 >>> Mark Lord wrote: >>> >>>> Arjan van de Ven wrote: >>>>> On Fri, 30 Nov 2007 22:14:08 -0500 >>>>> Mark Lord wrote: >>>>> >>>>>>> in -mm there is.. the QoS stuff allows you to set maximum >>>>>>> tolerable >>>>>> .. >>>>>> >>>>>> That's encouraging, I think, but not for 2.6.24. >>>>>> >>>>>>> latency. If your app cant take any latency, you should set >>>>>>> those... and the side effect is that the kernel will not do >>>>>>> long-latency C-states or P-state transitions.. >>>>>> .. >>>>>> >>>>>> I don't mind the cpufreq changing (actually, I want it to drop in >>>>>> cpugfreq to save power and keep the fan off), but the >> C-states just >>>>>> kill this app. >>>>>> >>>>>> The app is VMware. I force the max_state=1 when launching, >>>>> ah but then its' even easier... and can be done in 2.6.24 already. >>>>> VMWare after all has a kernel module, and the latency stuff is in >>>>> 2.6.23 and 2.6.24 available inside the kernel already. >>>> .. >>>> >>>> Oh, I'm perfectly happy to write my own kernel module if that's what >>> all you need to do in your kernel module is call >>> >>> add_latency_constraint("mark_wants_his_mouse", 5); >>> >>> or so >> .. >> >> Dredging up an old regression again now: >> >> The "make my own module to replace /sys/.../max_cstate" doesn't work >> for the single-core machine we use a lot around here. >> >> VMware is totally sluggish unless I go to another text window >> and do this: >> >> while ( true ); do echo -n ; done >> >> At which point VMware performs well again, >> the same as with "echo 1 > max_cstate" in 2.6.23. >> >> Anyone got any suggestions on how to fix this regression >> or work around it for 2.6.24 ? >> > > Easiest and clean way to do it is to have a driver with > set_acceptable_latency() for 1uS or so in init and > remove_acceptable_latency() at exit. .. As noted, I already do that. It helps with my Core2Duo machine, but not with the single-core case. Bummer. -ml