[PATCH] perf test: test case 17 fails on s390 on z/vm

From: Thomas Richter
Date: Tue Dec 19 2023 - 09:37:20 EST


perf test 17 'Setup struct perf_event_attr' fails on s390 z/VM guest,
using linux-next kernel.
Root cause is the fall-back from hardware counter cycles

perf_event_attr:
type 0 (PERF_TYPE_HARDWARE)
size 136
config 0 (PERF_COUNT_HW_CPU_CYCLES)
{ sample_period, sample_freq } 4000
sample_type IP|TID|TIME|ADDR|PERIOD|DATA_SRC
read_format ID|LOST

which returns -ENOENT on s390 z/VM guest. This causes the code to
fall back to software counter task-clock, as can be seen in the
debug output.
------------------------------------------------------------
perf_event_attr:
type 1 (PERF_TYPE_SOFTWARE)
size 136
config 0x1 (PERF_COUNT_SW_TASK_CLOCK) <-here
{ sample_period, sample_freq } 4000
sample_type IP|TID|TIME|ADDR|PERIOD|DATA_SRC
read_format ID|LOST

This succeeds on s390 z/VM guest.
This successful installation of the counter task-clock is not listed
in the expected results and the test case fails.

This is caused by commit
commit eb2eac0c7b61 ("perf evsel: Fallback to "task-clock" when not system wide")
which introduced fall back from event 'cycles' to event 'task-clock'.

To fix this on s390 allow event number 0 (cycles) and event number 1
(task-clock) as expected result.

Output before:
# ./perf test -Fv 17
17: Setup struct perf_event_attr :
--- start ---
running './tests/attr/test-stat-group1'
unsupp './tests/attr/test-stat-group1'
running './tests/attr/test-record-graph-default'
test limitation '!aarch64'
excluded architecture list ['aarch64']
expected config=0, got 1
FAILED './tests/attr/test-record-graph-default' - match failure
---- end ----
Setup struct perf_event_attr: FAILED!
#

Output after:
# ./perf test -F 17
17: Setup struct perf_event_attr : Ok
#

Fixes: eb2eac0c7b61 ("perf evsel: Fallback to "task-clock" when not system wide")
Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
---
tools/perf/tests/attr/base-record | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/attr/base-record b/tools/perf/tests/attr/base-record
index 27c21271a16c..b44e4e6e4443 100644
--- a/tools/perf/tests/attr/base-record
+++ b/tools/perf/tests/attr/base-record
@@ -6,7 +6,7 @@ flags=0|8
cpu=*
type=0|1
size=136
-config=0
+config=0|1
sample_period=*
sample_type=263
read_format=0|4|20
--
2.43.0