From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752829AbcHQPE4 (ORCPT ); Wed, 17 Aug 2016 11:04:56 -0400 Received: from smtprelay0120.hostedemail.com ([216.40.44.120]:43291 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752286AbcHQPEw (ORCPT ); Wed, 17 Aug 2016 11:04:52 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::,RULES_HIT:41:355:379:541:599:800:960:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1539:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:2693:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3868:3870:3872:3874:4250:5007:6261:7875:10004:10400:10848:10967:11232:11658:11914:12296:12517:12519:12740:13069:13208:13229:13311:13357:13439:14181:14659:14721:21067:21080:21121:30054:30055:30090:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:2,LUA_SUMMARY:none X-HE-Tag: brake02_2a369d4f5b902 X-Filterd-Recvd-Size: 1965 Date: Wed, 17 Aug 2016 11:04:48 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: Thomas Gleixner , Ingo Molnar , Alexander Shishkin , linux-kernel@vger.kernel.org Subject: Re: [RFC] ftrace / perf 'recursion' Message-ID: <20160817110448.20b4a6db@gandalf.local.home> In-Reply-To: <20160817145709.GS30192@twins.programming.kicks-ass.net> References: <20160817091953.GH7141@twins.programming.kicks-ass.net> <20160817103306.GI7141@twins.programming.kicks-ass.net> <20160817105716.GJ7141@twins.programming.kicks-ass.net> <20160817094932.22a9e768@gandalf.local.home> <20160817140612.GR30192@twins.programming.kicks-ass.net> <20160817102559.726742bf@gandalf.local.home> <20160817145709.GS30192@twins.programming.kicks-ass.net> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; 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 On Wed, 17 Aug 2016 16:57:09 +0200 Peter Zijlstra wrote: > We'd still need the irq_work to wake tasks stuck in poll() and friends. > And once we're over the watermark, every new event will trigger that > wakeup, and the wakeup will generate a new event etc.. I just byte the bullet for those (first OS world) issues. If one wants to trace wake ups, and the wake up of the trace task gets traced, which causes the trace task to wake up more often, and add more events, then so be it. I like to see how the tracer affects the system as well. I noticed that hiding the tracer can make it confusing if one sees gaps in the trace, where it was the tracer causing it. -- Steve