From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752122AbdAaNJk (ORCPT ); Tue, 31 Jan 2017 08:09:40 -0500 Received: from mail.kernel.org ([198.145.29.136]:57870 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751882AbdAaNJc (ORCPT ); Tue, 31 Jan 2017 08:09:32 -0500 Date: Tue, 31 Jan 2017 09:46:29 -0300 From: Arnaldo Carvalho de Melo To: Taeung Song Cc: linux-kernel@vger.kernel.org, Jiri Olsa , Namhyung Kim , Ingo Molnar , Peter Zijlstra , Wang Nan Subject: Re: [PATCH v2 2/4] perf ftrace: Add ftrace.tracer config option Message-ID: <20170131124628.GC4491@kernel.org> References: <1485862711-20216-1-git-send-email-treeze.taeung@gmail.com> <1485862711-20216-3-git-send-email-treeze.taeung@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1485862711-20216-3-git-send-email-treeze.taeung@gmail.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Tue, Jan 31, 2017 at 08:38:29PM +0900, Taeung Song escreveu: > Currently perf ftrace command will select 'function_graph' or 'function'. > So add ftrace.tracer config option to select tracer The above is confusing, I changed it to: Currently 'perf ftrace' command allows selecting 'function_graph' or 'function', defaulting to 'function_graph'. Add the ftrace.tracer config option to select the default tracer: > # cat ~/.perfconfig > [ftrace] > tracer = function > > # perf ftrace usleep 123456 | head -10 > <...>-14450 [002] d... 10089.284231: finish_task_switch <-__schedule > <...>-14450 [002] .... 10089.284232: finish_wait <-pipe_wait > <...>-14450 [002] .... 10089.284232: mutex_lock <-pipe_wait > <...>-14450 [002] .... 10089.284232: _cond_resched <-mutex_lock > > Cc: Jiri Olsa > Cc: Namhyung Kim > Signed-off-by: Taeung Song > --- > tools/perf/builtin-ftrace.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > index 414444d..00e228f 100644 > --- a/tools/perf/builtin-ftrace.c > +++ b/tools/perf/builtin-ftrace.c > @@ -17,6 +17,7 @@ > #include "evlist.h" > #include "target.h" > #include "thread_map.h" > +#include "util/config.h" > > > #define DEFAULT_TRACER "function_graph" > @@ -198,6 +199,26 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > return done ? 0 : -1; > } > > +static int perf_ftrace_config(const char *var, const char *value, void *cb) > +{ > + struct perf_ftrace *ftrace = cb; > + > + if (!strcmp(var, "ftrace.tracer")) { > + if (!strcmp(value, "function_graph")) > + ftrace->tracer = DEFAULT_TRACER; > + else if (!strcmp(value, "function")) > + ftrace->tracer = "function"; > + else { > + pr_err("Please select function_graph(default)" > + "or function to use tracer.\n"); > + return -1; > + } If you use {} in the else case, use it in the other branch, also I simplified it to be: + if (!strcmp(var, "ftrace.tracer")) { + if (!strcmp(value, "function_graph") || + !strcmp(value, "function")) + ftrace->tracer = value; + else { + pr_err("Please select function_graph(default)" + "or function to use tracer.\n"); + return -1; + } As we know item->value will not go away (its a perf_config_item, allocated and kept in that perf_config_set structure). Also it doesn't make sense comparing against "function_graph" to set it to DEFAULT_TRACER, as if we decide to change the DEFAULT_TRACER this simply breaks. Also you forgot to test by setting an invalid tracer, I did and noticed that you forgot to add a space between "(default)" and "or ", please be more careful with testing. Also you are silently ignoring any unknown variable in this section, so if someone has this: cat ~/.perfconfig [ftrace] trace = function I.e. forgets the 'r', it will keep using the current default, "function_graph" till the user checks the config and adds that missing 'r'... I haven't changed this because I think this is so common that we should instead have a different error return for those config callbacks that will tell perf_config() to say something like: "unknown variable %s.%s\n", section_name, variable_name - Arnaldo > + return 0; > + } > + > + return 0; > +} > + > int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused) > { > int ret; > @@ -218,6 +239,10 @@ int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused) > OPT_END() > }; > > + ret = perf_config(perf_ftrace_config, &ftrace); > + if (ret < 0) > + return -1; > + > argc = parse_options(argc, argv, ftrace_options, ftrace_usage, > PARSE_OPT_STOP_AT_NON_OPTION); > if (!argc) > -- > 2.7.4