From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755067AbdKAQ60 (ORCPT ); Wed, 1 Nov 2017 12:58:26 -0400 Received: from foss.arm.com ([217.140.101.70]:49380 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754997AbdKAQ6Y (ORCPT ); Wed, 1 Nov 2017 12:58:24 -0400 Subject: Re: [PATCH 2/2] perf: Fix ftrace builtin when kernel doesn't have function_graph To: Steven Rostedt Cc: linux-arm-kernel@lists.infradead.org, takahiro.akashi@linaro.org, Will Deacon , Mark Rutland , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org References: <1509546824-46165-1-git-send-email-julien.thierry@arm.com> <1509546824-46165-3-git-send-email-julien.thierry@arm.com> <20171101124433.1a6ed9c6@gandalf.local.home> From: Julien Thierry Message-ID: <047da0c7-6552-e6bb-d044-7cb5e05c431d@arm.com> Date: Wed, 1 Nov 2017 16:58:20 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20171101124433.1a6ed9c6@gandalf.local.home> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/11/17 16:44, Steven Rostedt wrote: > On Wed, 1 Nov 2017 14:33:44 +0000 > Julien Thierry wrote: > >> When linux is built without support for function graph tracer, the ftrace >> builtin of perf will fail when trying to reset max_graph_depth because the >> file does not exist. This prevents the use of function tracer from perf. >> >> Do not attempt to write this file when the tracer in use is not >> function_graph. >> >> Signed-off-by: Julien Thierry >> Cc: Will Deacon >> Cc: Mark Rutland >> Cc: Peter Zijlstra >> Cc: Ingo Molnar >> Cc: linux-kernel@vger.kernel.org >> --- >> tools/perf/builtin-ftrace.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c >> index 25a42ac..48120f2 100644 >> --- a/tools/perf/builtin-ftrace.c >> +++ b/tools/perf/builtin-ftrace.c >> @@ -130,7 +130,8 @@ static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused) >> if (reset_tracing_cpu() < 0) >> return -1; >> >> - if (write_tracing_file("max_graph_depth", "0") < 0) >> + if (!strcmp(ftrace->tracer, "function_graph") && >> + write_tracing_file("max_graph_depth", "0") < 0) > > Hmm, instead of doing this, could we just do a stat on the file first. > As with trace-cmd, I like to reset files like this even when not > enabling function_graph tracer. > Sounds reasonable. I'll include that change in the next version of the patches. Thanks, -- Julien Thierry From mboxrd@z Thu Jan 1 00:00:00 1970 From: julien.thierry@arm.com (Julien Thierry) Date: Wed, 1 Nov 2017 16:58:20 +0000 Subject: [PATCH 2/2] perf: Fix ftrace builtin when kernel doesn't have function_graph In-Reply-To: <20171101124433.1a6ed9c6@gandalf.local.home> References: <1509546824-46165-1-git-send-email-julien.thierry@arm.com> <1509546824-46165-3-git-send-email-julien.thierry@arm.com> <20171101124433.1a6ed9c6@gandalf.local.home> Message-ID: <047da0c7-6552-e6bb-d044-7cb5e05c431d@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 01/11/17 16:44, Steven Rostedt wrote: > On Wed, 1 Nov 2017 14:33:44 +0000 > Julien Thierry wrote: > >> When linux is built without support for function graph tracer, the ftrace >> builtin of perf will fail when trying to reset max_graph_depth because the >> file does not exist. This prevents the use of function tracer from perf. >> >> Do not attempt to write this file when the tracer in use is not >> function_graph. >> >> Signed-off-by: Julien Thierry >> Cc: Will Deacon >> Cc: Mark Rutland >> Cc: Peter Zijlstra >> Cc: Ingo Molnar >> Cc: linux-kernel at vger.kernel.org >> --- >> tools/perf/builtin-ftrace.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c >> index 25a42ac..48120f2 100644 >> --- a/tools/perf/builtin-ftrace.c >> +++ b/tools/perf/builtin-ftrace.c >> @@ -130,7 +130,8 @@ static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused) >> if (reset_tracing_cpu() < 0) >> return -1; >> >> - if (write_tracing_file("max_graph_depth", "0") < 0) >> + if (!strcmp(ftrace->tracer, "function_graph") && >> + write_tracing_file("max_graph_depth", "0") < 0) > > Hmm, instead of doing this, could we just do a stat on the file first. > As with trace-cmd, I like to reset files like this even when not > enabling function_graph tracer. > Sounds reasonable. I'll include that change in the next version of the patches. Thanks, -- Julien Thierry