Messages in this thread Patch in this message | | | From | Arnaldo Carvalho de Melo <> | Subject | [PATCH 14/17] perf record: Change warning for missing sysfs entry to debug | Date | Fri, 13 Apr 2018 11:01:08 -0300 |
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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
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