From: Thomas Richter <tmricht@linux.ibm.com>
To: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
acme@kernel.org
Cc: brueckner@linux.vnet.ibm.com, schwidefsky@de.ibm.com,
heiko.carstens@de.ibm.com, Thomas Richter <tmricht@linux.ibm.com>
Subject: [PATCH] perf record: Change warning for missing sysfs entry to debug
Date: Thu, 12 Apr 2018 15:32:46 +0200 [thread overview]
Message-ID: <20180412133246.92801-1-tmricht@linux.ibm.com> (raw)
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 <tmricht@linux.ibm.com>
---
| 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--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
next reply other threads:[~2018-04-12 13:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-12 13:32 Thomas Richter [this message]
2018-04-12 17:22 ` [PATCH] perf record: Change warning for missing sysfs entry to debug Arnaldo Carvalho de Melo
2018-04-16 6:47 ` [tip:perf/urgent] " tip-bot for Thomas Richter
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