lkml.org 
[lkml]   [2014]   [Feb]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:perf/core] perf list: Fix checking for supported events on older kernels
Commit-ID:  88fee52e58ca14d8465b614774ed0bf08e1a7790
Gitweb: http://git.kernel.org/tip/88fee52e58ca14d8465b614774ed0bf08e1a7790
Author: Vince Weaver <vincent.weaver@maine.edu>
AuthorDate: Mon, 30 Dec 2013 15:39:45 -0500
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 10 Feb 2014 11:34:31 -0300

perf list: Fix checking for supported events on older kernels

"perf list" listing of hardware events doesn't work on older ARM devices.
The change enabling event detection:

commit b41f1cec91c37eeea6fdb15effbfa24ea0a5536b
Author: Namhyung Kim <namhyung.kim@lge.com>
Date: Tue Aug 27 11:41:53 2013 +0900

perf list: Skip unsupported events

uses the following code in tools/perf/util/parse-events.c:

struct perf_event_attr attr = {
.type = type,
.config = config,
.disabled = 1,
.exclude_kernel = 1,
};

On ARM machines pre-dating the Cortex-A15 this doesn't work, as these
machines don't support .exclude_kernel. So starting with 3.12 "perf
list" does not report any hardware events at all on older machines (seen
on Rasp-Pi, Pandaboard, Beagleboard, etc).

This version of the patch makes changes suggested by Namhyung Kim to
check for EACCESS and retry (instead of just dropping the
exclude_kernel) so we can properly handle machines where
/proc/sys/kernel/perf_event_paranoid is set to 2.

Reported-by: Chad Paradis <chad.paradis@umit.maine.edu>
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Chad Paradis <chad.paradis@umit.maine.edu>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1312301536150.28814@vincent-weaver-1.um.maine.edu
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/parse-events.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index d248fca..1e15df1 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1091,12 +1091,12 @@ int is_valid_tracepoint(const char *event_string)
static bool is_event_supported(u8 type, unsigned config)
{
bool ret = true;
+ int open_return;
struct perf_evsel *evsel;
struct perf_event_attr attr = {
.type = type,
.config = config,
.disabled = 1,
- .exclude_kernel = 1,
};
struct {
struct thread_map map;
@@ -1108,7 +1108,20 @@ static bool is_event_supported(u8 type, unsigned config)

evsel = perf_evsel__new(&attr);
if (evsel) {
- ret = perf_evsel__open(evsel, NULL, &tmap.map) >= 0;
+ open_return = perf_evsel__open(evsel, NULL, &tmap.map);
+ ret = open_return >= 0;
+
+ if (open_return == -EACCES) {
+ /*
+ * This happens if the paranoid value
+ * /proc/sys/kernel/perf_event_paranoid is set to 2
+ * Re-run with exclude_kernel set; we don't do that
+ * by default as some ARM machines do not support it.
+ *
+ */
+ evsel->attr.exclude_kernel = 1;
+ ret = perf_evsel__open(evsel, NULL, &tmap.map) >= 0;
+ }
perf_evsel__delete(evsel);
}


\
 
 \ /
  Last update: 2014-02-22 19:41    [W:0.080 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site