Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754541Ab2BURft (ORCPT ); Tue, 21 Feb 2012 12:35:49 -0500 Received: from merlin.infradead.org ([205.233.59.134]:36676 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753024Ab2BURfr (ORCPT ); Tue, 21 Feb 2012 12:35:47 -0500 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Stephane Eranian , David Ahern , Eric Dumazet , Peter Zijlstra , Arnaldo Carvalho de Melo Subject: [PATCH 3/3] perf tools: fix broken perf record -a mode Date: Tue, 21 Feb 2012 15:35:27 -0200 Message-Id: <1329845727-21512-4-git-send-email-acme@infradead.org> X-Mailer: git-send-email 1.7.9.123.g65da0 In-Reply-To: <1329845727-21512-1-git-send-email-acme@infradead.org> References: <1329845727-21512-1-git-send-email-acme@infradead.org> X-SRS-Rewrite: SMTP reverse-path rewritten from by canuck.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 Content-Length: 2287 Lines: 64 From: Stephane Eranian The following commit: b52956c perf tools: Allow multiple threads or processes in record, stat, top introduced a bug in the thread_map code which caused perf record -a to not setup system-wide monitoring properly. $ taskset -c 1 noploop 1000 & $ perf record -a -C 1 sleep 10 $ perf report -D | tail -20 cycles stats: TOTAL events: 4413 MMAP events: 4025 COMM events: 340 SAMPLE events: 48 Here I was expecting about 10,000 samples and not 48. In system-wide mode, the PID passed to perf_event_open() must be -1 and it was 0. That caused the kernel to setup a per-process event on PID:0. Consequently, the number of samples captured does not correspond to the requested measurement. The following one-liner fixes the problem for me with or without -C. I would also suggest to change the malloc() to something that matches the struct definition. thread_map->map[] is declared as int map[] and not pid_t map[]. If map[] can only contain pids, then change the struct definition. Acked-by: David Ahern Cc: David Ahern Cc: Eric Dumazet Cc: Ingo Molnar Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20120221145424.GA6757@quad Signed-off-by: Stephane Eranian Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/thread_map.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c index e15983c..84d9bd78 100644 --- a/tools/perf/util/thread_map.c +++ b/tools/perf/util/thread_map.c @@ -229,7 +229,7 @@ static struct thread_map *thread_map__new_by_tid_str(const char *tid_str) if (!tid_str) { threads = malloc(sizeof(*threads) + sizeof(pid_t)); if (threads != NULL) { - threads->map[1] = -1; + threads->map[0] = -1; threads->nr = 1; } return threads; -- 1.7.9.123.g65da0 -- 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/