From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751659AbaLPQ5r (ORCPT ); Tue, 16 Dec 2014 11:57:47 -0500 Received: from mail.kernel.org ([198.145.19.201]:46741 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751214AbaLPQ5p (ORCPT ); Tue, 16 Dec 2014 11:57:45 -0500 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Arnaldo Carvalho de Melo , Adrian Hunter , Borislav Petkov , David Ahern , Don Zickus , Frederic Weisbecker , Jiri Olsa , Mike Galbraith , Namhyung Kim , Paul Mackerras , Peter Zijlstra , Stephane Eranian Subject: [PATCH 03/18] perf evlist: Improve the strerror_mmap method Date: Tue, 16 Dec 2014 13:57:05 -0300 Message-Id: <1418749040-31807-4-git-send-email-acme@kernel.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1418749040-31807-1-git-send-email-acme@kernel.org> References: <1418749040-31807-1-git-send-email-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnaldo Carvalho de Melo Considering the per user locked pages limit, improve the message when a user uses multiple simultaneous perf mmap calls: When the request is more than the current maximum: [acme@ssdandy linux]$ trace -m 128 usleep 1 Error: Operation not permitted. Hint: Check /proc/sys/kernel/perf_event_mlock_kb (516 kB) setting. Hint: Tried using 516 kB. Hint: Try 'sudo sh -c "echo 1032 > /proc/sys/kernel/perf_event_mlock_kb"', or Hint: Try using a smaller -m/--mmap-pages value. [acme@ssdandy linux]$ And when the limit is less than that: [acme@ssdandy linux]$ trace -m 512 usleep 1 Error: Operation not permitted. Hint: Check /proc/sys/kernel/perf_event_mlock_kb (2056 kB) setting. Hint: Tried using 2052 kB. Hint: Try using a smaller -m/--mmap-pages value. [acme@ssdandy linux]$ Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Don Zickus Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Mike Galbraith Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Stephane Eranian Link: http://lkml.kernel.org/n/tip-yqdie3c8qvdgenwleri267d4@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evlist.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index d661f252b891..7847f3885081 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -1487,16 +1487,25 @@ int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused, int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, size_t size) { char sbuf[STRERR_BUFSIZE], *emsg = strerror_r(err, sbuf, sizeof(sbuf)); - int pages_attempted = evlist->mmap_len / 1024, pages_max_per_user; + int pages_attempted = evlist->mmap_len / 1024, pages_max_per_user, printed = 0; switch (err) { case EPERM: sysctl__read_int("kernel/perf_event_mlock_kb", &pages_max_per_user); - scnprintf(buf, size, "Error:\t%s.\n" + printed += scnprintf(buf + printed, size - printed, + "Error:\t%s.\n" "Hint:\tCheck /proc/sys/kernel/perf_event_mlock_kb (%d kB) setting.\n" - "Hint:\tTried using %zd kB.\n" - "Hint:\tTry using a smaller -m/--mmap-pages value.", + "Hint:\tTried using %zd kB.\n", emsg, pages_max_per_user, pages_attempted); + + if (pages_attempted >= pages_max_per_user) { + printed += scnprintf(buf + printed, size - printed, + "Hint:\tTry 'sudo sh -c \"echo %d > /proc/sys/kernel/perf_event_mlock_kb\"', or\n", + pages_max_per_user + pages_attempted); + } + + printed += scnprintf(buf + printed, size - printed, + "Hint:\tTry using a smaller -m/--mmap-pages value."); break; default: scnprintf(buf, size, "%s", emsg); -- 1.9.3