From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753745Ab2AILM5 (ORCPT ); Mon, 9 Jan 2012 06:12:57 -0500 Received: from merlin.infradead.org ([205.233.59.134]:52694 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752811Ab2AILMz convert rfc822-to-8bit (ORCPT ); Mon, 9 Jan 2012 06:12:55 -0500 Message-ID: <1326107563.2442.65.camel@twins> Subject: Re: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken From: Peter Zijlstra To: Youquan Song Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, akpm@linux-foundation.org, stable@vger.kernel.org, suresh.b.siddha@intel.com, arjan@linux.intel.com, len.brown@intel.com, anhua.xu@intel.com, chaohong.guo@intel.com, Youquan Song Date: Mon, 09 Jan 2012 12:12:43 +0100 In-Reply-To: <20120110001445.GA20542@linux-youquan.bj.intel.com> References: <1326099367-4166-1-git-send-email-youquan.song@intel.com> <1326103578.2442.50.camel@twins> <20120110001445.GA20542@linux-youquan.bj.intel.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-01-09 at 19:14 -0500, Youquan Song wrote: > > Yes it is.. also that knob should die! Like i've been saying for way too > > long. I'm >< close to committing a patch removing all the power_saving > > magic from the scheduler. > Sorry. I do not notice it. I hadn't posted it before, but just about every time people post something related to smt/mc power balancing I say this needs to get cleaned up. Since telling people doesn't seem to have any effect what so ever, stronger measures are needed. > But currently in many real tests, the knob prove to save power in semi-idle system. > They are useful in many user scenarios currently. I'm not saying the stuff is without merit, I'm just saying that a) the interface is utter crap and b) nobody seems to spend enough time on it to 1) understand the load-balancer so that 2) he can integrate the power saving stuff properly. Instead I get one sporadic band-aid after another. Also, fundamentally, the split between {smt/mc/numa/book}_power_savings is completely and fundamentally broken, nobody cares about the actual topology.