lkml.org 
[lkml]   [2018]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 14/17] perf record: Change warning for missing sysfs entry to debug
Date
From: Thomas Richter <tmricht@linux.ibm.com>

Using perf on 4.16.0 kernel on s390 shows this warning:

failed: can't open node sysfs data

each time I run command perf record ... for example:

[root@s35lp76 perf]# ./perf record -e rB0000 -- sleep 1
[ perf record: Woken up 1 times to write data ]
failed: can't open node sysfs data
[ perf record: Captured and wrote 0.001 MB perf.data (4 samples) ]
[root@s35lp76 perf]#

It turns out commit e2091cedd51bf ("perf tools: Add MEM_TOPOLOGY feature
to perf data file") tries to open directory named /sys/devices/system/node/
which does not exist on s390.

This is the call stack:
__cmd_record
+---> perf_session__write_header
+---> perf_header__adds_write
+---> do_write_feat
+---> write_mem_topology
+---> build_mem_topology
prints warning

The issue starts in do_write_feat() which unconditionally loops over all
features and now includes HEADER_MEM_TOPOLOGY and calls write_mem_topology().

Function record__init_features() at the beginning of __cmd_record() sets
all features and then turns off some of them.

Fix this by changing the warning to a level 2 debug output statement.

So it is only shown when debug level 2 or higher is set.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180412133246.92801-1-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/header.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 121df1683c36..a8bff2178fbc 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1320,7 +1320,8 @@ static int build_mem_topology(struct memory_node *nodes, u64 size, u64 *cntp)

dir = opendir(path);
if (!dir) {
- pr_warning("failed: can't open node sysfs data\n");
+ pr_debug2("%s: could't read %s, does this arch have topology information?\n",
+ __func__, path);
return -1;
}

--
2.14.3
\
 
 \ /
  Last update: 2018-04-13 16:04    [W:0.026 / U:0.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site