From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754924Ab3KTWIm (ORCPT ); Wed, 20 Nov 2013 17:08:42 -0500 Received: from mga11.intel.com ([192.55.52.93]:49988 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750858Ab3KTWIk (ORCPT ); Wed, 20 Nov 2013 17:08:40 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.93,739,1378882800"; d="scan'208";a="436915185" Date: Wed, 20 Nov 2013 14:08:21 -0800 From: Jacob Pan To: Thomas Gleixner Cc: Arjan van de Ven , Peter Zijlstra , lenb@kernel.org, rjw@rjwysocki.net, Eliezer Tamir , Chris Leech , David Miller , rui.zhang@intel.com, Mike Galbraith , Ingo Molnar , hpa@zytor.com, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, "Rafael J. Wysocki" Subject: Re: [PATCH 3/7] idle, thermal, acpi: Remove home grown idle implementations Message-ID: <20131120140821.1d5607c2@ultegra> In-Reply-To: References: <20131120160450.072555619@infradead.org> <20131120162736.508462614@infradead.org> <528CE611.8040903@linux.intel.com> <528CF028.2040002@linux.intel.com> <528CFDB1.3020300@linux.intel.com> Organization: OTC X-Mailer: Claws Mail 3.8.1 (GTK+ 2.24.17; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Nov 2013 20:38:03 +0100 (CET) Thomas Gleixner wrote: > On Wed, 20 Nov 2013, Arjan van de Ven wrote: > > > > but for powerclamp to work, it needs to inject a deep idle.... I'm > > very ok using generic abstractions for that, but the abstraction > > needs to then include a "don't be nice about picking shallow C > > states for performance reasons, just pick something very deep" > > parameter. > > And that's what you should have done in the first place. Make the > generic code take a parameter to indicate that. Or tell the scheduler > to throttle the machine and go deep idle. That would also be helpful > to others who might need some similar thing. > I thought about that. Since the generic code is in performance critical path and idle injection is a rare case. Then the question is do we want sacrifice the 99% for %1 usage? > No, you went with the worst design: > > - Hack it into some random driver > - Export random core interfaces so it's harder to change them > - Let others deal with the fallout > > I'm cleaning up that kind of mess for more than 9 years now and I'm > really disappointed that you went over to the "who cares, works for > me" camp. > > I can lively remember our discussions when we were cleaning up the > whole timer mess together in order to make NOHZ actually useful. Your > cursing about such code was definitely impressive back then. > > Thanks, > > tglx > > > > [Jacob Pan]