From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755056AbaHBR6u (ORCPT ); Sat, 2 Aug 2014 13:58:50 -0400 Received: from smtp1-g21.free.fr ([212.27.42.1]:28636 "EHLO smtp1-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754712AbaHBR6s (ORCPT ); Sat, 2 Aug 2014 13:58:48 -0400 Message-ID: <1407002305.3573.12.camel@dworkin> Subject: Re: [PATCH] perf tools: Show better error message in case we fail to open counters due to EBUSY error From: Yann Droneaud To: Jiri Olsa Cc: linux-kernel@vger.kernel.org, Adrian Hunter , Arnaldo Carvalho de Melo , David Ahern , Frederic Weisbecker , Namhyung Kim , Paul Mackerras , Peter Zijlstra , Stephane Eranian , William Cohen , ydroneaud@opteya.com Date: Sat, 02 Aug 2014 19:58:25 +0200 In-Reply-To: <1406908014-8312-1-git-send-email-jolsa@kernel.org> References: <1406908014-8312-1-git-send-email-jolsa@kernel.org> Organization: OPTEYA Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4 (3.10.4-2.fc20) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jiri, Le vendredi 01 août 2014 à 17:46 +0200, Jiri Olsa a écrit : > Showing better error message in case we fail to open > counters due to the EBUSY error. If we detect oprofile > daemon process running, we now display following message > for EBUSY error: > > $ perf record ls > Error: > The PMU counters are busy/taken by another profiler. > We found oprofile daemon running, please stop it and try again. > > In case oprofiled was not detected the current error > message stays: > > $ perf record ls > Error: > The sys_perf_event_open() syscall returned with 16 (Device or resource busy) for event (cycles). > /bin/dmesg may provide additional information. > No CONFIG_PERF_EVENTS=y kernel support configured? > > Also changing PERF_FLAG_FD_CLOEXEC detection code not to display > error in case of EBUSY error, as it currently does: > > $ perf record ls > Error: > perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error 16 (Device or resource busy) > perf_event_open(..., 0) failed unexpectedly with error 16 (Device or resource busy) > The PMU counters are busy/taken by another profiler. > We found oprofile daemon running, please stop it and try again. > > Cc: Adrian Hunter > Cc: Arnaldo Carvalho de Melo > Cc: David Ahern > Cc: Frederic Weisbecker > Cc: Namhyung Kim > Cc: Paul Mackerras > Cc: Peter Zijlstra > Cc: Stephane Eranian > Cc: William Cohen > Cc: Yann Droneaud > Signed-off-by: Jiri Olsa > --- > tools/perf/util/cloexec.c | 4 ++-- > tools/perf/util/evsel.c | 6 ++++++ > tools/perf/util/util.c | 36 ++++++++++++++++++++++++++++++++++++ > tools/perf/util/util.h | 1 + > 4 files changed, 45 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c > index c5d05ec17220..dede0c388ed4 100644 > --- a/tools/perf/util/cloexec.c > +++ b/tools/perf/util/cloexec.c > @@ -25,7 +25,7 @@ static int perf_flag_probe(void) > return 1; > } > > - WARN_ONCE(err != EINVAL, > + WARN_ONCE(err != EINVAL && err != EBUSY, > "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n", > err, strerror(err)); > > @@ -33,7 +33,7 @@ static int perf_flag_probe(void) > fd = sys_perf_event_open(&attr, 0, -1, -1, 0); > err = errno; > > - if (WARN_ONCE(fd < 0, > + if (WARN_ONCE(fd < 0 && err != EBUSY, > "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n", > err, strerror(err))) > return -1; It's definitely possible to shortcut the function if EBUSY is returned by first call to perf_event_open(). diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c index dc360ebde745..d5c626d5432a 100644 --- a/tools/perf/util/cloexec.c +++ b/tools/perf/util/cloexec.c @@ -25,6 +25,9 @@ static int perf_flag_probe(void) return 1; } + if (err == EBUSY) + return -1; + WARN_ONCE(err != EINVAL, "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n", err, strerror(err)); BTW, I'm going to submit a patch to make the function report such warning only once. Regards. -- Yann Droneaud OPTEYA