Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751885AbcDZAuK (ORCPT ); Mon, 25 Apr 2016 20:50:10 -0400 Received: from mail-ig0-f174.google.com ([209.85.213.174]:38205 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751101AbcDZAuI (ORCPT ); Mon, 25 Apr 2016 20:50:08 -0400 MIME-Version: 1.0 In-Reply-To: <20160426004747.GC16708@kernel.org> References: <20160425161425.GA25218@kernel.org> <20160425162706.GB25218@kernel.org> <20160425192229.GC25218@kernel.org> <20160425200646.GA23875@ast-mbp.thefacebook.com> <20160425201750.GD25218@kernel.org> <20160425215947.GA25915@ast-mbp.thefacebook.com> <20160425234138.GA16708@kernel.org> <20160426000724.GA28705@ast-mbp.thefacebook.com> <20160426002928.GB16708@kernel.org> <20160426004358.GA29875@ast-mbp.thefacebook.com> <20160426004747.GC16708@kernel.org> From: Brendan Gregg Date: Mon, 25 Apr 2016 17:49:38 -0700 Message-ID: Subject: Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth via sysctl To: Arnaldo Carvalho de Melo Cc: Alexei Starovoitov , David Ahern , Peter Zijlstra , Frederic Weisbecker , Ingo Molnar , Adrian Hunter , Alexander Shishkin , Alexei Starovoitov , He Kuang , Jiri Olsa , Masami Hiramatsu , Milian Wolff , Namhyung Kim , Stephane Eranian , Thomas Gleixner , Vince Weaver , Wang Nan , Zefan Li , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1651 Lines: 45 On Mon, Apr 25, 2016 at 5:47 PM, Arnaldo Carvalho de Melo wrote: > Em Mon, Apr 25, 2016 at 05:44:00PM -0700, Alexei Starovoitov escreveu: >> On Mon, Apr 25, 2016 at 09:29:28PM -0300, Arnaldo Carvalho de Melo wrote: >> > Em Mon, Apr 25, 2016 at 05:07:26PM -0700, Alexei Starovoitov escreveu: >> > > > + { >> > > > + .procname = "perf_event_max_stack", >> > > > + .data = NULL, /* filled in by handler */ >> > > > + .maxlen = sizeof(sysctl_perf_event_max_stack), >> > > > + .mode = 0644, >> > > > + .proc_handler = perf_event_max_stack_handler, >> > > > + .extra1 = &zero, >> > > > + }, >> > >> > > you need to define a max value otherwise perf_callchain_entry__sizeof >> > > will overflow. Sure it's root only facility, but still not nice. >> > > 1M? Anything above 1M stack frames would be insane anyway. >> > > The rest looks good. Thanks! >> > >> > Something else? ;-) >> >> all looks good to me. Thanks a bunch! > > Thanks for checking! > >> > Because we only allocate the callchain percpu data structures when there >> > is a user, which allows for changing the max easily, its just a matter >> > of having no callchain users at that point. >> > >> > Reported-and-Tested-by: Brendan Gregg >> > Acked-by: Alexei Starovoitov >> >> yep :) >> hopefully Brendan can give it another spin. > > Agreed, and I'm calling it a day anyway, Brendan, please consider > retesting, thanks, > Will do, thanks! Brendan > - Arnaldo