Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755436Ab1DIOGD (ORCPT ); Sat, 9 Apr 2011 10:06:03 -0400 Received: from casper.infradead.org ([85.118.1.10]:34791 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753379Ab1DIOGB convert rfc822-to-8bit (ORCPT ); Sat, 9 Apr 2011 10:06:01 -0400 Subject: Re: [tip:perf/core] perf evsel: Fix inverted test for fixing up attr.inherit flag From: Peter Zijlstra To: mingo@redhat.com, hpa@zytor.com, acme@redhat.com, paulus@samba.org, eranian@google.com, linux-kernel@vger.kernel.org, tzanussi@gmail.com, efault@gmx.de, fweisbec@gmail.com, dsahern@gmail.com, tglx@linutronix.de, mingo@elte.hu Cc: linux-tip-commits@vger.kernel.org In-Reply-To: References:

Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Sat, 09 Apr 2011 16:05:42 +0200 Message-ID: <1302357942.9086.1281.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2860 Lines: 71 On Tue, 2011-02-22 at 09:10 +0000, tip-bot for Arnaldo Carvalho de Melo wrote: > Commit-ID: e603dc15072c7fec0ae263597e6dabc3bb4c5c5b > Gitweb: http://git.kernel.org/tip/e603dc15072c7fec0ae263597e6dabc3bb4c5c5b > Author: Arnaldo Carvalho de Melo > AuthorDate: Mon, 21 Feb 2011 16:05:50 -0300 > Committer: Arnaldo Carvalho de Melo > CommitDate: Mon, 21 Feb 2011 22:27:59 -0300 > > perf evsel: Fix inverted test for fixing up attr.inherit flag > > The kernel refuses mmapping an event with the inherit flag set for > something that is systemwide (cpu == -1), and the evsel layer got this > reversed at some point, fix it. > > The symtom was that the --pid and --tid parameters for 'perf record' and > 'perf top' returned with -EINVAL, like: > > # /tmp/build-perf/perf record -v -fo/tmp/perf.data -p 1042 > Warning: ... trying to fall back to cpu-clock-ticks > > Fatal: failed to mmap with 22 (Invalid argument) > > Reported-by: David Ahern > Cc: Frederic Weisbecker > Cc: Ingo Molnar > Cc: Mike Galbraith > Cc: Paul Mackerras > Cc: Peter Zijlstra > Cc: Stephane Eranian > Cc: Tom Zanussi > LKML-Reference: > Signed-off-by: Arnaldo Carvalho de Melo > --- > tools/perf/util/evsel.c | 15 +++++++++++++-- > 1 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index 63cadaf..8083d51 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -179,8 +179,19 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus, > > for (cpu = 0; cpu < cpus->nr; cpu++) { > int group_fd = -1; > - > - evsel->attr.inherit = (cpus->map[cpu] < 0) && inherit; > + /* > + * Don't allow mmap() of inherited per-task counters. This > + * would create a performance issue due to all children writing > + * to the same buffer. > + * > + * FIXME: > + * Proper fix is not to pass 'inherit' to perf_evsel__open*, > + * but a 'flags' parameter, with 'group' folded there as well, > + * then introduce a PERF_O_{MMAP,GROUP,INHERIT} enum, and if > + * O_MMAP is set, emit a warning if cpu < 0 and O_INHERIT is > + * set. Lets go for the minimal fix first tho. > + */ > + evsel->attr.inherit = (cpus->map[cpu] >= 0) && inherit; > This wrecked perf-stat, perf-stat doesn't mmap and its perfectly fine for it to use task-bound counters with inheritance. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/