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From:   Thomas Richter <tmricht@linux.ibm.com>
To:     linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        acme@kernel.org, irogers@google.com, sumanthk@linux.ibm.com,
        eranian@google.com
Cc:     svens@linux.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com,
        Thomas Richter <tmricht@linux.ibm.com>
Subject: [PATCH][Ping] perf test: Test 17 fails with make LIBPFM4=1 on s390 z/VM
Date:   Thu, 20 May 2021 15:52:26 +0200
Message-Id: <20210520135226.2335704-1-tmricht@linux.ibm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

This test case fails on s390 virtual machine z/VM which has no PMU support
when the perf tool is built with LIBPFM4=1.

Using make LIBPFM4=1 builds the perf tool with support for libpfm
event notation. The command line flag --pfm-events is valid:
 # ./perf record --pfm-events cycles -- true
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.001 MB perf.data (2 samples) ]
 #

However the command 'perf test -Fv 17' fails on s390 z/VM virtual machine
with LIBPFM4=1:
  # perf test -Fv 17
  17: Setup struct perf_event_attr                                    :
  --- start ---
  .....
  running './tests/attr/test-record-group2'
  unsupp  './tests/attr/test-record-group2'
  running './tests/attr/test-record-pfm-period'
  expected exclude_hv=0, got 1
 FAILED './tests/attr/test-record-pfm-period' - match failure
 ---- end ----
 Setup struct perf_event_attr: FAILED!

When --pfm-event system is not supported, the test returns unsupported
and continues. Here is an example using a virtual machine on x86 and
Fedora 34:
 [root@f33 perf]# perf test -Fv 17
 17: Setup struct perf_event_attr                                    :
 --- start ---
 .....
 running './tests/attr/test-record-group2'
 unsupp  './tests/attr/test-record-group2'
 running './tests/attr/test-record-pfm-period'
 unsupp  './tests/attr/test-record-pfm-period'
 ....

The issue is file ./tests/attr/test-record-pfm-period
which requires perf event attribute member exclude_hv to be zero.
This is not the case on s390 where the value of exclude_hv is one when
executing on a z/VM virtual machine without PMU hardware support.

Fix this by allowing value exlucde_hv to be zero or one.

Output before:
 # /usr/bin/python ./tests/attr.py -d ./tests/attr/ -t \
	test-record-pfm-period -p ./perf  -vvv 2>&1| fgrep match
    matching [event:base-record]
    match: [event:base-record] matches []
 FAILED './tests/attr//test-record-pfm-period' - match failure
 #

Output after:
 # /usr/bin/python ./tests/attr.py -d ./tests/attr/ -t \
	test-record-pfm-period -p ./perf  -vvv 2>&1| fgrep match
    matching [event:base-record]
    match: [event:base-record] matches ['event-1-0-6', 'event-1-0-5']
  matched
    matching [event-1-0-6]
    match: [event-1-0-6] matches ['event:base-record']
    matching [event-1-0-5]
    match: [event-1-0-5] matches ['event:base-record']
  matched
 #

Background:
Using libpfm library ends up in this function call sequence

pfm_get_perf_event_encoding()
+-- pfm_get_os_event_encoding()
    +-- pfmlib_perf_event_encode()

is called when no hardware specific PMU unit can be detected
as in the s390 z/VM virtual machine case. This uses the
"perf_events generic PMU" data structure which sets exclude_hv per default.
Using this PMU that test case always fails.

That is the reason why exclude_hv attribute setting varies.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/attr/test-record-pfm-period | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/tests/attr/test-record-pfm-period b/tools/perf/tests/attr/test-record-pfm-period
index 368f5b814094..b962d6d11ee2 100644
--- a/tools/perf/tests/attr/test-record-pfm-period
+++ b/tools/perf/tests/attr/test-record-pfm-period
@@ -7,3 +7,4 @@ ret     = 1
 sample_period=77777
 sample_type=7
 freq=0
+exclude_hv=0|1
-- 
2.30.2