From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758794AbaELPRx (ORCPT ); Mon, 12 May 2014 11:17:53 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.231]:54209 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758430AbaELPRv (ORCPT ); Mon, 12 May 2014 11:17:51 -0400 Date: Mon, 12 May 2014 11:17:48 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: Dongsheng Yang , "yangds.fnst" , linux-kernel@vger.kernel.org, mingo@redhat.com, bsegall@google.com Subject: Re: [PATCH] sched: Distinguish sched_wakeup event when wake up a task which did schedule out or not. Message-ID: <20140512111748.1c2f6cd9@gandalf.local.home> In-Reply-To: <20140512150950.GP30445@twins.programming.kicks-ass.net> References: <53683B14.3060702@cn.fujitsu.com> <1399341154-11785-1-git-send-email-yangds.fnst@cn.fujitsu.com> <20140510152902.GW11096@twins.programming.kicks-ass.net> <536F90BE.2080806@gmail.com> <20140511163531.GG30445@twins.programming.kicks-ass.net> <20140511145224.00412e59@gandalf.local.home> <20140512064730.GI30445@twins.programming.kicks-ass.net> <20140512100908.07cc50bc@gandalf.local.home> <20140512150950.GP30445@twins.programming.kicks-ass.net> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.22; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 12 May 2014 17:09:50 +0200 Peter Zijlstra wrote: > > Point being, this is useful information, why not pass it to userspace? > > Because it adds code to one of the hottest code paths in the kernel and > so far nobody had a sane explanation of WTF they were doing. > Is there a measurable difference with these extra tracepoints? -- Steve