From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755510AbcCXMZz (ORCPT ); Thu, 24 Mar 2016 08:25:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48543 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750728AbcCXMZr (ORCPT ); Thu, 24 Mar 2016 08:25:47 -0400 Date: Thu, 24 Mar 2016 13:25:44 +0100 From: Jiri Olsa To: Peter Zijlstra Cc: Jiri Olsa , Steven Rostedt , lkml , Ingo Molnar , Namhyung Kim , Arnaldo Carvalho de Melo Subject: Re: [PATCH 2/5] ftrace perf: Move exclude_kernel tracepoint check to init event Message-ID: <20160324122544.GA12449@krava.brq.redhat.com> References: <1458138873-1553-1-git-send-email-jolsa@kernel.org> <1458138873-1553-3-git-send-email-jolsa@kernel.org> <20160323104129.GZ6344@twins.programming.kicks-ass.net> <20160324095648.GC8893@krava.brq.redhat.com> <20160324104934.GQ6356@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160324104934.GQ6356@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 24, 2016 at 11:49:34AM +0100, Peter Zijlstra wrote: > On Thu, Mar 24, 2016 at 10:56:48AM +0100, Jiri Olsa wrote: > > On Wed, Mar 23, 2016 at 11:41:29AM +0100, Peter Zijlstra wrote: > > > On Wed, Mar 16, 2016 at 03:34:30PM +0100, Jiri Olsa wrote: > > > > We suppress events with attr::exclude_kernel set when > > > > the event is generated, so following capture will > > > > give no warning but won't produce any data: > > > > > > > > $ sudo perf record -e sched:sched_switch:u ls > > > > $ sudo /perf script | wc -l > > > > 0 > > > > > > > > Checking the attr::exclude_(kernel|user) at the event > > > > init time and failing right away for tracepoints from > > > > uprobes/kprobes and native ones: > > > > > > > > $ sudo perf record -e sched:sched_switch:u ls > > > > Error: > > > > The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (sched:sched_switch). > > > > /bin/dmesg may provide additional information. > > > > No CONFIG_PERF_EVENTS=y kernel support configured? > > > > Not sure about this one. The previous behaviour suggests > > > exclude_{user,kernel} is implemented, while the new behaviour says these > > > flags are not implemented, which is a functional regression. > > > > well I would not expect 'sched:sched_switch:u' to work (be implemented) > > > > and I thought it's better to trigger an error than silently 'produce' no data > > We're not in the business of protecting people from themselves are we? > And if you want to help them, do so in userspace. yep, I planned to make user space patch to make that error more user friendly > > And its not like the [uk] flags are hard to implement here. sched:sched_switch:u ? jirka