linux-kernel - [PATCH 1/6] perf tools: Show event fd in debug output

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Message-Id: <1479764011-10732-2-git-send-email-jolsa@kernel.org>
Date:   Mon, 21 Nov 2016 22:33:26 +0100
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Don Zickus <dzickus@...hat.com>, Joe Mario <jmario@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Andi Kleen <andi@...stfloor.org>
Subject: [PATCH 1/6] perf tools: Show event fd in debug output

It was useful for debug to see file descriptors for each event.

Before:

  $ perf stat -vvv -e cycles,cache-misses ls
  ...
  sys_perf_event_open: pid 12146  cpu -1  group_fd -1  flags 0x8
  ...
  sys_perf_event_open: pid 12146  cpu -1  group_fd 3  flags 0x8
  sys_perf_event_open failed, error -13

Now:

  $ perf stat -vvv -e cycles,cache-misses ls
  ...
  sys_perf_event_open: pid 12858  cpu -1  group_fd -1  flags 0x8 = 3
  ...
  sys_perf_event_open: pid 12858  cpu -1  group_fd 3  flags 0x8
  sys_perf_event_open failed, error -13

Link: http://lkml.kernel.org/n/tip-7drsvjamul8bawh8ga1vpnx1@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...hat.com>
---
 tools/perf/util/evsel.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index e58a2fbf3b16..b2365a63db45 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1481,7 +1481,7 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
 
 			group_fd = get_group_fd(evsel, cpu, thread);
 retry_open:
-			pr_debug2("sys_perf_event_open: pid %d  cpu %d  group_fd %d  flags %#lx\n",
+			pr_debug2("sys_perf_event_open: pid %d  cpu %d  group_fd %d  flags %#lx",
 				  pid, cpus->map[cpu], group_fd, flags);
 
 			FD(evsel, cpu, thread) = sys_perf_event_open(&evsel->attr,
@@ -1490,11 +1490,13 @@ static int __perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus,
 								     group_fd, flags);
 			if (FD(evsel, cpu, thread) < 0) {
 				err = -errno;
-				pr_debug2("sys_perf_event_open failed, error %d\n",
+				pr_debug2("\nsys_perf_event_open failed, error %d\n",
 					  err);
 				goto try_fallback;
 			}
 
+			pr_debug2(" = %d\n", FD(evsel, cpu, thread));
+
 			if (evsel->bpf_fd >= 0) {
 				int evt_fd = FD(evsel, cpu, thread);
 				int bpf_fd = evsel->bpf_fd;
-- 
2.7.4