From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754711AbcKUTPX (ORCPT ); Mon, 21 Nov 2016 14:15:23 -0500 Received: from smtprelay0032.hostedemail.com ([216.40.44.32]:43025 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752835AbcKUTPW (ORCPT ); Mon, 21 Nov 2016 14:15:22 -0500 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 50,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:967:973:988:989:1260:1263:1277:1311:1313:1314:1345:1359:1431:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2194:2199:2393:2525:2553:2560:2563:2682:2685:2859:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3352:3622:3865:3866:3867:3868:3870:3871:3872:3873:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4250:5007:6261:7875:7903:9025:9108:9388:10004:10400:10450:10455:10848:10967:11232:11658:11914:12043:12114:12740:12760:13069:13161:13180:13229:13311:13357:13439:14096:14097:14181:14659:14721:19904:19999:21080:21451:30054:30070:30090:30091,0,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: unit52_68a3c0e14a94f X-Filterd-Recvd-Size: 2535 Date: Mon, 21 Nov 2016 14:15:17 -0500 From: Steven Rostedt To: Andi Kleen Cc: Peter Zijlstra , Jiri Olsa , "Paul E. McKenney" , linux-kernel@vger.kernel.org, Ingo Molnar , Josh Triplett , Jan Stancek Subject: Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Message-ID: <20161121141517.31936dbe@gandalf.local.home> In-Reply-To: <20161121183700.GW26852@two.firstfloor.org> References: <20161121005343.GB1891@krava> <20161121092850.GF3102@twins.programming.kicks-ass.net> <20161121170612.GT26852@two.firstfloor.org> <20161121171853.GK3092@twins.programming.kicks-ass.net> <20161121174504.GU26852@two.firstfloor.org> <20161121130115.2f0f38e7@gandalf.local.home> <20161121180654.GV26852@two.firstfloor.org> <20161121132220.17fb0515@gandalf.local.home> <20161121183700.GW26852@two.firstfloor.org> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; 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 Mon, 21 Nov 2016 10:37:00 -0800 Andi Kleen wrote: > Just adding a few inlines won't fix the gigantic bloat that is currently > there. See the PT trace I posted earlier (it was even truncated, it's > actually worse). Just a single enabled trace point took about a us. If you want to play with that, enable "Add tracepoint that benchmarks tracepoints", and enable /sys/kernel/debug/tracing/events/benchmark I just did on my box, and I have a max of 1.27 us, average .184 us. Thus, on average, a tracepoint takes 184 nanoseconds. Note, a cold cache tracepoint (the first one it traced which is not saved in the "max") was 3.3 us. Yes it can still be improved, and I do spend time doing that. > > POPF can cause some serializion but it won't be more than a few tens > of cycles, which would be a few percent at best. > > Here is it again untruncated: > > http://halobates.de/tracepoint-trace There's a lot of push and pop regs due to function calling. There's places that inlines can still improve things, and perhaps even some likely unlikelys well placed. -- Steve