From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751380AbaLPQ5i (ORCPT ); Tue, 16 Dec 2014 11:57:38 -0500 Received: from mail.kernel.org ([198.145.19.201]:46693 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751214AbaLPQ5g (ORCPT ); Tue, 16 Dec 2014 11:57:36 -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 01/18] perf evlist: Fixup brown paper bag on "hint" for --mmap-pages cmdline arg Date: Tue, 16 Dec 2014 13:57:03 -0300 Message-Id: <1418749040-31807-2-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 When failing due to asking for a number of mmap pages that is more than the max, it was suggesting that an even bigger number of mmap pages should be specified, doh, au contraire! Before: [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 using a bigger -m/--mmap-pages value. [acme@ssdandy linux]$ After: [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 using a smaller -m/--mmap-pages value. [acme@ssdandy linux]$ And to (really) clarify what happens above, when what the user requests is <= max and even then it fails, a changeset is being made to tell that this is a per user limit, not per process (in the above example there was another 'perf trace' running for this user, which was using all the pages it could use). 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-8qope8lxb898narnq5kmu2gf@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evlist.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index bb5dfc5d1e75..de7515dd683a 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -1495,7 +1495,7 @@ int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, s scnprintf(buf, size, "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 bigger -m/--mmap-pages value.", + "Hint:\tTry using a smaller -m/--mmap-pages value.", emsg, value, evlist->mmap_len / 1024); break; default: -- 1.9.3