From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757518Ab0DOHq4 (ORCPT ); Thu, 15 Apr 2010 03:46:56 -0400 Received: from casper.infradead.org ([85.118.1.10]:46659 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756173Ab0DOHqz (ORCPT ); Thu, 15 Apr 2010 03:46:55 -0400 Subject: Re: [PATCH 1/3] [kidled]: introduce kidled. From: Peter Zijlstra To: Salman Qazi Cc: Andi Kleen , mingo@elte.hu, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, svaidy@linux.vnet.ibm.com, linux-pm@lists.linux-foundation.org, arjan@infradead.org, csadler@google.com, ranjitm@google.com, kenchen@google.com, dawnchen@google.com In-Reply-To: References: <20100413234902.29004.41655.stgit@bumblebee1.mtv.corp.google.com> <20100414000823.29004.98991.stgit@bumblebee1.mtv.corp.google.com> <87fx2y9xdn.fsf@basil.nowhere.org> Content-Type: text/plain; charset="UTF-8" Date: Thu, 15 Apr 2010 09:46:51 +0200 Message-ID: <1271317611.32749.68.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-04-14 at 08:41 -0700, Salman Qazi wrote: > > To capture all the quantities for a CPU atomically, they must be read > on the CPU. Basically, reading them on that CPU prevents them from > changing as we read them. > > Also, if the CPU is idle (injected or otherwise), the quantities won't > get updated. Who cares? by the time they reach userspace they've changed anyway.