From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751861AbeCVTLq (ORCPT ); Thu, 22 Mar 2018 15:11:46 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:50950 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751748AbeCVTLn (ORCPT ); Thu, 22 Mar 2018 15:11:43 -0400 Date: Thu, 22 Mar 2018 20:11:27 +0100 From: Peter Zijlstra To: Rik van Riel Cc: "Rafael J. Wysocki" , Linux PM , Frederic Weisbecker , Thomas Gleixner , Paul McKenney , Thomas Ilsche , Doug Smythies , Aubrey Li , Mike Galbraith , LKML Subject: Re: [PATCH v2] cpuidle: poll_state: Add time limit to poll_idle() Message-ID: <20180322191127.GY4043@hirez.programming.kicks-ass.net> References: <4137867.C4jYrWdt8n@aspire.rjw.lan> <20180314120450.GT4043@hirez.programming.kicks-ass.net> <1521736338.6308.24.camel@surriel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1521736338.6308.24.camel@surriel.com> User-Agent: Mutt/1.9.3 (2018-01-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 22, 2018 at 12:32:18PM -0400, Rik van Riel wrote: > On Wed, 2018-03-14 at 13:04 +0100, Peter Zijlstra wrote: > > > On x86 we don't have to use that time_check_counter thing, > > sched_clock() > > is really cheap, not sure if it makes sense on other platforms. > > Are you sure? I saw a 5-10% increase in CPU use, > for a constant query rate to a memcache style > workload, with v3 of this patch. Well, I expected it to be really cheap, but if you have numbers saying otherwise, clearly I'll need to adjust expectations ;-)