From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751806AbaLPQ6A (ORCPT ); Tue, 16 Dec 2014 11:58:00 -0500 Received: from mail.kernel.org ([198.145.19.201]:46810 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751767AbaLPQ55 (ORCPT ); Tue, 16 Dec 2014 11:57:57 -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 05/18] perf evlist: Do not use hard coded value for a mmap_pages default Date: Tue, 16 Dec 2014 13:57:07 -0300 Message-Id: <1418749040-31807-6-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 So far what is in there by default is what we were using: 512KB + the control page, but the admin may change that, and if it does to a smaller value, all calls to tooling for non root users start failing, requiring that the user manually set --mmap_pages/-m. Use instead what is in /proc/sys/kernel/perf_event_mlock_kb. 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-2f6mtm8xu3wo5lhkql6jdblh@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evlist.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 7847f3885081..ac808680e61c 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -893,10 +893,22 @@ out_unmap: static size_t perf_evlist__mmap_size(unsigned long pages) { - /* 512 kiB: default amount of unprivileged mlocked memory */ - if (pages == UINT_MAX) - pages = (512 * 1024) / page_size; - else if (!is_power_of_2(pages)) + if (pages == UINT_MAX) { + int max; + + if (sysctl__read_int("kernel/perf_event_mlock_kb", &max) < 0) { + /* + * Pick a once upon a time good value, i.e. things look + * strange since we can't read a sysctl value, but lets not + * die yet... + */ + max = 512; + } else { + max -= (page_size / 1024); + } + + pages = (max * 1024) / page_size; + } else if (!is_power_of_2(pages)) return 0; return (pages + 1) * page_size; -- 1.9.3