From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751447AbbF3Ojc (ORCPT ); Tue, 30 Jun 2015 10:39:32 -0400 Received: from mail.kernel.org ([198.145.29.136]:34617 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475AbbF3OjY (ORCPT ); Tue, 30 Jun 2015 10:39:24 -0400 Date: Tue, 30 Jun 2015 11:39:09 -0300 From: Arnaldo Carvalho de Melo To: Adrian Hunter Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Jiri Olsa , David Ahern , Namhyung Kim , Peter Zijlstra , Stephane Eranian Subject: Re: [GIT PULL 0/8] perf/pt -> Intel PT/BTS Message-ID: <20150630143909.GC5888@kernel.org> References: <1435356140-31212-1-git-send-email-acme@kernel.org> <20150630045852.GB31981@gmail.com> <55924B2D.7000903@intel.com> <20150630105648.GA25749@gmail.com> <55929861.3050000@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55929861.3050000@intel.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Tue, Jun 30, 2015 at 04:23:45PM +0300, Adrian Hunter escreveu: > On 30/06/15 13:56, Ingo Molnar wrote: > > > > * Adrian Hunter wrote: > > > >>> Yeah, so I did a 'newbie test': > >>> > >>> I pulled the tree and saw that it has a tools/perf/Documentation/intel-bts.txt > >>> file and started reading it. > >>> > >>> Based on its text: > >>> > >>> The Intel BTS kernel driver creates a new PMU for Intel BTS. The perf record > >>> option is: > >>> > >>> -e intel_bts// > >>> > >>> Currently Intel BTS is limited to per-thread tracing so the --per-thread option > >>> is also needed. > >>> > >>> I tried the following command which failed: > >>> > >>> triton:~/tip> perf record -e intel_bts// --per-thread sleep 1 > >>> invalid or unsupported event: 'intel_bts//' > >>> Run 'perf list' for a list of valid events > >>> > >>> usage: perf record [] [] > >>> or: perf record [] -- [] > >>> > >>> -e, --event event selector. use 'perf list' to list available events > >>> > >>> That's a really ... unhelpful message. If I typoed something I want to know that. > >>> If the kernel does not support something, I want to know about that too. Tooling > >>> telling me: "maybe you typoed something, maybe it's not supported, I really don't > >>> care" is not very productive. > >> > >> That is not entirely true. The message says "Run 'perf list' for a list of valid > >> events" which will tell you if the event is valid. So you can tell the > >> difference between a typo and unsupported event. > > > > Yeah, but my point is: why doesn't the tool do this disambiguation for me? Tools > > are hard enough to use as-is already, no need to put artificial roadblocks in the > > path of first time users. > > That applies to all events e.g. > > # perf record -e sched:sched_swotch sleep 1 > invalid or unsupported event: 'sched:sched_swotch' > Run 'perf list' for a list of valid events > > usage: perf record [] [] > or: perf record [] -- [] > > -e, --event event selector. use 'perf list' to list available events > > So it is a general problem. Right, guess it is interesting to note at this point that Jiri improved this area: [acme@zoo linux]$ perf record -e sched:sched_swotch sleep 1 event syntax error: 'sched:sched_swotch' \___ unknown tracepoint Run 'perf list' for a list of valid events usage: perf record [] [] or: perf record [] -- [] -e, --event event selector. use 'perf list' to list available events [acme@zoo linux]$ But: [acme@zoo linux]$ perf record -e intel_pt// usleep 1 invalid or unsupported event: 'intel_pt//' Run 'perf list' for a list of valid events usage: perf record [] [] or: perf record [] -- [] -e, --event event selector. use 'perf list' to list available events [acme@zoo linux]$ I'll investigate how this can be improved... - Arnaldo