From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759287AbXLTJcO (ORCPT ); Thu, 20 Dec 2007 04:32:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756047AbXLTJcD (ORCPT ); Thu, 20 Dec 2007 04:32:03 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:49192 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750933AbXLTJcB (ORCPT ); Thu, 20 Dec 2007 04:32:01 -0500 Date: Thu, 20 Dec 2007 10:31:39 +0100 From: Ingo Molnar To: Venki Pallipadi Cc: Thomas Gleixner , "H. Peter Anvin" , Len Brown , linux-kernel Subject: Re: [PATCH] x86: Voluntary leave_mm before entering ACPI C3 Message-ID: <20071220093138.GE4478@elte.hu> References: <20071219183443.GA547@linux-os.sc.intel.com> <20071219193255.GA2158@elte.hu> <20071220020846.GA13464@linux-os.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071220020846.GA13464@linux-os.sc.intel.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Venki Pallipadi wrote: > > Btw., since the TLB flush state machine is really subtle and > > fragile, could you try to run the following mmap stresstest i wrote > > some time ago: > > > > http://redhat.com/~mingo/threaded-mmap-stresstest/ > > > > for a couple of hours. It runs nr_cpus threads which then do a > > "random crazy mix" of mappings/unmappings/remappings of a 800 MB > > memory window. The more sockets/cores, the crazier the TLB races get > > ;-) > > > > Ingo, > > I ran this stress test on two systems (8 cores and 2 cores) for over 4 > hours without any issues. There was more than 20% C3 time during the > run. So, this C3 tlbflush path must have been stressed well during the > run. ok, great. Regarding power consumption: i suspect a real difference will only show up on multi-socket systems that can do deeper C modes, or on multicore systems that will benefit from longer idle time on another core. (i suspect most multicore CPUs today will only truly save significant amounts of power if all cores are idle.) In any case, not doing these extra IPIs is definitely a plus. Ingo