From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arjan van de Ven Subject: Re: [PATCH 3/7] idle, thermal, acpi: Remove home grown idle implementations Date: Thu, 21 Nov 2013 08:21:03 -0800 Message-ID: <528E32EF.2050300@linux.intel.com> References: <20131120160450.072555619@infradead.org> <20131120162736.508462614@infradead.org> <20131120165406.14fa0f09@ultegra> <20131121082151.GU10022@twins.programming.kicks-ass.net> <20131121160716.GT4138@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mga02.intel.com ([134.134.136.20]:22010 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751609Ab3KUQVE (ORCPT ); Thu, 21 Nov 2013 11:21:04 -0500 In-Reply-To: <20131121160716.GT4138@linux.vnet.ibm.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: paulmck@linux.vnet.ibm.com, Peter Zijlstra Cc: Jacob Pan , lenb@kernel.org, rjw@rjwysocki.net, Eliezer Tamir , Chris Leech , David Miller , rui.zhang@intel.com, Mike Galbraith , Ingo Molnar , hpa@zytor.com, Thomas Gleixner , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, "Rafael J. Wysocki" On 11/21/2013 8:07 AM, Paul E. McKenney wrote: > As long as RCU has some reliable way to identify an idle task, I am > good. But I have to ask -- why can't idle injection coordinate with > the existing idle tasks rather than temporarily making alternative > idle tasks? it's not a real idle. that's the whole problem of the situation. to the rest of the OS, this is being BUSY (busy saving power using a CPU instruction, but it might as well have been an mdelay() operation) and it's also what end users expect; they want to be able to see where there performance (read: cpu time in "top") is going.