From: Thomas Richter Date: Thu, 12 Apr 2018 13:32:46 +0000 (+0200) Subject: perf record: Change warning for missing sysfs entry to debug X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=4f75f1cbf95e2f0853cd229d042b203931b899af;p=openwrt%2Fstaging%2Fblogic.git 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 Cc: Heiko Carstens Cc: Hendrik Brueckner Cc: Martin Schwidefsky Link: http://lkml.kernel.org/r/20180412133246.92801-1-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- 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; }