From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757969Ab1LWV41 (ORCPT ); Fri, 23 Dec 2011 16:56:27 -0500 Received: from casper.infradead.org ([85.118.1.10]:50727 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757885Ab1LWVx3 (ORCPT ); Fri, 23 Dec 2011 16:53:29 -0500 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Nelson Elhage , Paul Mackerras , Peter Zijlstra , Arnaldo Carvalho de Melo Subject: [PATCH 07/15] perf: builtin-record: Document and check that mmap_pages must be a power of two. Date: Fri, 23 Dec 2011 19:53:10 -0200 Message-Id: <1324677198-5191-8-git-send-email-acme@infradead.org> X-Mailer: git-send-email 1.7.8.rc0.35.gee6df In-Reply-To: <1324677198-5191-1-git-send-email-acme@infradead.org> References: <1324677198-5191-1-git-send-email-acme@infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nelson Elhage Now that we automatically point users at it, let's provide them some guidance so that they hopefully don't just get mysterious EINVAL's from the kernel. Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1324301972-22740-4-git-send-email-nelhage@nelhage.com Signed-off-by: Nelson Elhage [ committer note: Made it work after 50a682c ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-record.txt | 2 +- tools/perf/builtin-record.c | 3 +++ tools/perf/util/evlist.c | 2 ++ tools/perf/util/util.h | 11 +++++++++++ 4 files changed, 17 insertions(+), 1 deletions(-) diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index 5a520f8..2937f7e 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -89,7 +89,7 @@ OPTIONS -m:: --mmap-pages=:: - Number of mmap data pages. + Number of mmap data pages. Must be a power of two. -g:: --call-graph:: diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index 56bb447..e873ae2 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -279,6 +279,9 @@ try_again: "/proc/sys/kernel/perf_event_mlock_kb,\n" "or try again with a smaller value of -m/--mmap_pages.\n" "(current value: %d)\n", opts->mmap_pages); + else if (!is_power_of_2(opts->mmap_pages)) + die("--mmap_pages/-m value must be a power of two."); + die("failed to mmap with %d (%s)\n", errno, strerror(errno)); } diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index 963d63d..fa18370 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -563,6 +563,8 @@ int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int 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)) + return -EINVAL; mask = pages * page_size - 1; diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h index 0128906..37be34d 100644 --- a/tools/perf/util/util.h +++ b/tools/perf/util/util.h @@ -245,4 +245,15 @@ int readn(int fd, void *buf, size_t size); #define _STR(x) #x #define STR(x) _STR(x) +/* + * Determine whether some value is a power of two, where zero is + * *not* considered a power of two. + */ + +static inline __attribute__((const)) +bool is_power_of_2(unsigned long n) +{ + return (n != 0 && ((n & (n - 1)) == 0)); +} + #endif -- 1.7.8.rc0.35.gee6df