Using perf on 4.16.0 kernel on s390 shows 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 <[email protected]>
---
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
Em Thu, Apr 12, 2018 at 03:32:46PM +0200, Thomas Richter escreveu:
> Using perf on 4.16.0 kernel on s390 shows warning
> failed: can't open node sysfs data
> each time I run command perf record ... for example:
Thanks, applied.
- Arnaldo
Commit-ID: 4f75f1cbf95e2f0853cd229d042b203931b899af
Gitweb: https://git.kernel.org/tip/4f75f1cbf95e2f0853cd229d042b203931b899af
Author: Thomas Richter <[email protected]>
AuthorDate: Thu, 12 Apr 2018 15:32:46 +0200
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Fri, 13 Apr 2018 09:59:56 -0300
perf record: Change warning for missing sysfs entry to debug
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 <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Hendrik Brueckner <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
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;
}