From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757032Ab2AKDwR (ORCPT ); Tue, 10 Jan 2012 22:52:17 -0500 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:40098 "EHLO e28smtp08.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756669Ab2AKDwO (ORCPT ); Tue, 10 Jan 2012 22:52:14 -0500 Date: Wed, 11 Jan 2012 09:22:01 +0530 From: Vaidyanathan Srinivasan To: Suresh Siddha Cc: Youquan Song , Peter Zijlstra , linux-kernel@vger.kernel.org, mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, akpm@linux-foundation.org, stable@vger.kernel.org, arjan@linux.intel.com, len.brown@intel.com, anhua.xu@intel.com, chaohong.guo@intel.com, Youquan Song Subject: Re: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken Message-ID: <20120111035156.GB7988@dirshya.in.ibm.com> Reply-To: svaidy@linux.vnet.ibm.com References: <1326099367-4166-1-git-send-email-youquan.song@intel.com> <1326103578.2442.50.camel@twins> <20120110001445.GA20542@linux-youquan.bj.intel.com> <1326107156.2442.59.camel@twins> <20120110055856.GA23741@linux-youquan.bj.intel.com> <1326153163.2366.7.camel@sbsiddha-mobl2> <20120110165426.GA20681@linux-youquan.bj.intel.com> <20120110165129.GC17432@dirshya.in.ibm.com> <1326222073.6283.9.camel@sbsiddha-mobl2> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1326222073.6283.9.camel@sbsiddha-mobl2> User-Agent: Mutt/1.5.21 (2010-09-15) x-cbid: 12011103-2000-0000-0000-000005FF9F32 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Suresh Siddha [2012-01-10 11:01:13]: > On Tue, 2012-01-10 at 22:21 +0530, Vaidyanathan Srinivasan wrote: > > * Youquan Song [2012-01-10 11:54:26]: > > > > > > > > > Youquan, As far as I know both the > > > > sched_smt_power_savings/sched_mc_power_savings are broken for atleast an > > > > year. > > > > > > > > Have you checked the state of 'sched_mc_power_savings' to see if it is > > > > working or gets addressed with your proposed patches? > > > Thanks Suresh! > > > > > > We have verified that sched_mc_power_savings works well in mainline and > > > -tip tree, only sched_smt_power_savings broken. > > > > Hi Suresh, > > > > My testing also shows that sched_mc works find and only sched_smt > > suffers from the group capacity problem at the core level. > > > > No. I just checked and it doesn't work as intended. > > On a 2 socket 8-core SMT system, I ran 8 cpu hoggers and just toggled > 'sched_mc_power_savings' between 0 and 1 multiple times. Irrespective of > the value, those 8 hoggers are distributed evenly between two sockets - > 4 each and doesn't change their positions. > > So I can bet it doesn't work. Hi Suresh, I had tested sched_mc_powersavings=2 on dual socket quad core HT nehalem. It worked as expected. Let me check the sched_mc_powersavings=1 case. I will not be surprised if it is broken. --Vaidy