Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751698AbbKIOna (ORCPT ); Mon, 9 Nov 2015 09:43:30 -0500 Received: from mga11.intel.com ([192.55.52.93]:5913 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750856AbbKIOnY (ORCPT ); Mon, 9 Nov 2015 09:43:24 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,266,1444719600"; d="scan'208";a="681427533" Date: Mon, 9 Nov 2015 06:43:20 -0800 From: Jacob Pan To: Peter Zijlstra Cc: Punit Agrawal , Eduardo Valentin , Thomas Gleixner , LKML , Arjan van de Ven , Paul Turner , Len Brown , Srinivas Pandruvada , Tim Chen , Andi Kleen , Rafael Wysocki , jacob.jun.pan@linux.intel.com Subject: Re: [RFC PATCH 0/3] CFS idle injection Message-ID: <20151109064320.4280e3be@yairi> In-Reply-To: <20151109141534.GL17308@twins.programming.kicks-ass.net> References: <1446509428-5616-1-git-send-email-jacob.jun.pan@linux.intel.com> <20151104060654.GC8850@localhost.localdomain> <20151104085830.010e69f8@yairi> <20151105101218.GB3604@twins.programming.kicks-ass.net> <9hhvb9f843c.fsf@e105922-lin.cambridge.arm.com> <20151106111838.6172085d@icelake> <9hhbnb38jy4.fsf@e105922-lin.cambridge.arm.com> <20151109141534.GL17308@twins.programming.kicks-ass.net> Organization: OTC X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.23; 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 Content-Length: 1906 Lines: 42 On Mon, 9 Nov 2015 15:15:34 +0100 Peter Zijlstra wrote: > On Mon, Nov 09, 2015 at 11:56:51AM +0000, Punit Agrawal wrote: > > Jacob Pan writes: > > > My take is that RT and throttling will never go well together > > > since they are conflicting in principle. > > > > I am not sure I follow. If RT (or other higher priority classes) > > can't be throttled then the CPUs are not able to contribute towards > > constraining power consumption and hence temperature. > > > > This is especially true in certain platforms where tasks belong to > > the RT class to maintain user experience, e.g., audio and video. > > Audio/Video playback generally doesn't take a _lot_ of time these > days. What is important though is _when_ it happens. > > And media playback typically already has a very well defined and > stable cadence (24Hz or whatnot). What you want is for your idle > injector to sync up with that, not disrupt it. > Agreed, i have tested idle injection on video playback (mostly one cpu busy, no sync with gpu), it does not do well to improve energy efficiency. With the video playback being offloaded, there is no thermal condition either. So outside the scope of this first patchst trying to solve. The ability to sync with external pattern, could be the next step. kind of like pll in hw :). > For other workloads, missing a deadline is about as bad as destroying > the chip, complete system shutdown might be safer than getting > delayed. (The very tired scenario of a saw, a laser and your finger; > you want to shut down the entire machine rather than just cut off > your finger.) > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/