linux-kernel - [tip:perf/core] perf tools: fix broken perf record -a mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <tip-6b1bee9035d430c4b4f586df6df4b3f840e89b5b@git.kernel.org>
Date:	Wed, 22 Feb 2012 08:03:19 -0800
From:	tip-bot for Stephane Eranian <eranian@...gle.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	acme@...hat.com, linux-kernel@...r.kernel.org, eranian@...gle.com,
	hpa@...or.com, mingo@...hat.com, eric.dumazet@...il.com,
	peterz@...radead.org, dsahern@...il.com, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:perf/core] perf tools: fix broken perf record -a mode

Commit-ID:  6b1bee9035d430c4b4f586df6df4b3f840e89b5b
Gitweb:     http://git.kernel.org/tip/6b1bee9035d430c4b4f586df6df4b3f840e89b5b
Author:     Stephane Eranian <eranian@...gle.com>
AuthorDate: Tue, 21 Feb 2012 15:54:25 +0100
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Tue, 21 Feb 2012 15:05:43 -0200

perf tools: fix broken perf record -a mode

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 <dsahern@...il.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/20120221145424.GA6757@quad
Signed-off-by: Stephane Eranian <eranian@...gle.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 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;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/