From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932816AbXBOO0E (ORCPT ); Thu, 15 Feb 2007 09:26:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965306AbXBOO0D (ORCPT ); Thu, 15 Feb 2007 09:26:03 -0500 Received: from ausmtp05.au.ibm.com ([202.81.18.154]:58818 "EHLO ausmtp05.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932816AbXBOO0C (ORCPT ); Thu, 15 Feb 2007 09:26:02 -0500 Date: Thu, 15 Feb 2007 19:55:42 +0530 From: Gautham R Shenoy To: "Rafael J. Wysocki" Cc: akpm@osdl.org, paulmck@us.ibm.com, mingo@elte.hu, vatsa@in.ibm.com, dipankar@in.ibm.com, venkatesh.pallipadi@intel.com, linux-kernel@vger.kernel.org, oleg@tv-sign.ru Subject: Re: [RFC PATCH(Experimental) 0/4] Freezer based Cpu-hotplug Message-ID: <20070215142542.GA14931@in.ibm.com> Reply-To: ego@in.ibm.com References: <20070214144031.GA15257@in.ibm.com> <200702150909.53145.rjw@sisk.pl> <20070215122055.GA19155@in.ibm.com> <200702151431.10068.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200702151431.10068.rjw@sisk.pl> User-Agent: Mutt/1.5.12-2006-07-14 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 15, 2007 at 02:31:08PM +0100, Rafael J. Wysocki wrote: > > So I think tonight I'll start adding try_to_freeze() to the kernel threads that > set PF_NOFREEZE. cool! While you are at it, let me try to enhance the freezer api's to incorporate the PFE_* flags. > > > > That would still mean going over the task list twice. > > Yes, but I think this is inevitable anyway, because we have moved the > disabling of nonboot CPUs after the suspending of devices (for > ACPI-related reasons). > > Currently, we have, roughly: > > freeze_processes(); > shrink_memory(); (swsusp only) > suspend_devices(); > disable_nonboot_cpus(); > suspend > > and the reverse during the resume. > > Still, the second pass will be quick, since the majority of tasks are frozen > when disable_nonboot_cpus() is called. Ok. That's fine by me. Lets get it working first. We can always optimize it later :-) > > > > Cool! Lets get started then ;-) > > No problem with that. ;-) > > Speaking of the classification, do you think it would be practical to use > some kind of "freezing levels"? I mean, for each task we can define the > "freezing level" at which it should be frozen and each user of the freezer > can call it with a specific "freezing level" as a parameter. Of course for > this purpose the tasks frozen at level 1 have to be a subset of the tasks > frozen at level 2 etc. and I'm not sure if this requirement can be satisfied. A freeze hierarchy! I hope this freeze_level parameter ain't an alternative to the PFE_* flags because then a task would be in a dilemma as to what freezing level it should be at, if it wants to be frozen for lets say kprobes but not for cpu-hotplug. Cpu-hotplug and kprobes may not have a dependency like the one that exists between cpu-hotplug and suspend. So, at this moment, even I am not sure if there is a need for the hierarchy. > > Rafael Thanks and Regards gautham. -- Gautham R Shenoy Linux Technology Center IBM India. "Freedom comes with a price tag of responsibility, which is still a bargain, because Freedom is priceless!"