linux.git/tools/perf/tests/shell/stat.sh, branch v7.3-rc2

perf stat: Add --hide-zero-events option to suppress zero-count events

2026-07-20T04:49:30+00:00

When monitoring a large number of events (e.g., with wildcards such as
--event 'syscalls:sys_enter_*'), many matched events will return a count
of zero. This clutters the output, making it difficult to spot the
active events.

Add a new option --hide-zero-events to suppress printing events that
have a count of zero.

To prevent formatting and diagnostic issues, the zero-skipping logic
implements the following rules:

    1. In metric-only mode (i.e., --metric-only), columns must remain
       aligned in the output grid. We evaluate config->metric_only first
       to avoid skipping zero-valued columns, preventing values from
       shifting left and aligning under incorrect headers

    2. For explicitly requested events, we ensure they are not silently
       hidden if they are unsupported. We only hide a zero-count event
       if counter->supported is true, ensuring that unsupported explicit
       events still report ""

Signed-off-by: Aaron Tomlin 
Reviewed-by: Ian Rogers 
Signed-off-by: Namhyung Kim

perf stat: reject --field-separator and --json-output combination

2026-07-08T23:43:25+00:00

Specifying --field-separator option is stating you want CSV output.
Passing both --field-separator and --json-output is then stating
you want output to be in CSV and JSON format at same time.

Currently this combination is not rejected, and the outcome
is a malformed combination of CSV and JSON output.
This is because of inconsistencies in various printing functions,
some of them have if-else chains that start with
"Should I print JSON?", and some start with "Should I print CSV?".

Example of current output:
$ tools/perf/perf stat -x , -j -e cpu-migrations true
{"counter-value" : "0.000000", "unit" : "", "event" : "cpu-migrations", "event-runtime" : 474817, "pcnt-running" : 100.00,,

Instead reject the option combination,
with a helpful error message and non-zero exit code.

Example of new output:
$ tools/perf/perf stat -x , -j true
cannot use both --field-separator and --json-output

 Usage: perf stat [] []

    -x, --field-separator 
                          print counts with custom separator
    -j, --json-output     print counts in JSON format

Signed-off-by: Ivan Lazaric 
Signed-off-by: Namhyung Kim

perf tests: Add test for stat delay option with duration_time

2026-05-23T00:39:28+00:00

Add a new test case `test_stat_delay` to `stat.sh` to verify that
`duration_time` correctly excludes the delay period when using the
delay option (-D).

The test runs `perf stat -D 1000 -e duration_time sleep 2` and
verifies that `duration_time` is ~1s (excluding the 1s delay), not
~2s.

Assisted-by: Antigravity:gemini-3-flash
Signed-off-by: Ian Rogers 
Cc: Adrian Hunter 
Cc: Francesco Nigro 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Thomas Richter 
Signed-off-by: Arnaldo Carvalho de Melo

perf tests: Additional 'perf stat' tests

2026-02-06T14:55:21+00:00

Recently 'perf stat' regressed in per CPU mode [1].

Let's expand test coverage to catch the same breakage again as well as
to test the repeat, pid, detailed and no aggregation options.

[1] https://lore.kernel.org/linux-perf-users/cgja46br2smmznxs7kbeabs6zgv3b4olfqgh2fdp5mxk2yom4v@w6jjgov6hdi6/

Signed-off-by: Ian Rogers 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Andres Freund 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Thomas Richter 
Signed-off-by: Arnaldo Carvalho de Melo

perf test stat tests: Fix for virtualized machines

2026-01-12T18:48:26+00:00

On s390 'perf test's 'perf stat tests', subtest test_hybrid fails for
z/VM systems.  The root cause is this statement:

  $(perf stat -a -- sleep 0.1 2>&1 |\
                  grep -E "/cpu-cycles/[uH]*|  cpu-cycles[:uH]* -c)

The 'perf stat' output on a s390 z/VM system is

  # perf stat -a -- sleep 0.1 2>&1
  Performance counter stats for 'system wide':

        56      context-switches  #     46.3 cs/sec  cs_per_second
  1,210.41 msec cpu-clock         #     11.9 CPUs  CPUs_utilized
        12      cpu-migrations    #      9.9 migrations/sec ...
        81      page-faults       #     66.9 faults/sec ...

        0.100891009 seconds time elapsed

The grep command does not match any single line and exits with error
code 1.

As the bash script is executed with 'set -e', it aborts with the first
error code being non-zero.

Fix this and use 'wc -l' to count matching lines instead of 'grep ... -c'.

Output before:

  # perf test 102
  102: perf stat tests                      : FAILED!
  #

Output after:

  # perf test 102
  102: perf stat tests                      : Ok
  #

Fixes: bb6e7cb11d97ce19 ("perf tools: Add fallback for exclude_guest")
Reviewed-by: Ian Rogers 
Reviewed-by: James Clark 
Signed-off-by: Thomas Richter 
Cc: Alexander Gordeev 
Cc: Heiko Carstens 
Cc: Jan Polensky 
Cc: linux-s390@vger.kernel.org
Cc: Namhyung Kim 
Cc: Sumanth Korikkar 
Cc: Vasily Gorbik 
Signed-off-by: Arnaldo Carvalho de Melo

perf tests stat: Add test for error for an offline CPU

2025-12-04T23:42:29+00:00

Add a test that if an offline CPU is requested perf stat will fail.

  $ perf test -vv "perf stat tests"
  101: perf stat tests:
  --- start ---
  test child forked, pid 46965
  Basic stat command test
  Basic stat command test [Success]
  Null stat command test
  Null stat command test [Success]
  Offline CPU stat command test (cpu 8)
  Offline CPU stat command test [Success]
  stat record and report test
  stat record and report test [Success]
  stat record and script test
  stat record and script test [Success]
  stat repeat weak groups test
  stat repeat weak groups test [Success]
  Topdown event group test
  Topdown event group test [Success]
  Topdown weak groups test
  Topdown weak groups test [Skipped event parsing failed]
  cputype test
  cputype test [Success]
  hybrid test
  hybrid test [Success]
  ---- end(0) ----
  101: perf stat tests                                                 : Ok

Reported-by: Thomas Richter 
Closes: https://lore.kernel.org/linux-perf-users/94313b82-888b-4f42-9fb0-4585f9e90080@linux.ibm.com/
Signed-off-by: Ian Rogers 
Signed-off-by: Namhyung Kim

perf tests stat: Add "--null" coverage

2025-12-04T08:36:14+00:00

Ensure "--null" does a minimal run.

Reported-by: Ingo Molnar 
Closes: https://lore.kernel.org/linux-perf-users/aSwt7yzFjVJCEmVp@gmail.com/
Tested-by: Ingo Molnar 
Signed-off-by: Ian Rogers 
Tested-by: Thomas Richter 
Signed-off-by: Namhyung Kim

perf test stat: Update test expectations and events

2025-11-12T00:48:35+00:00

test_stat_record_report and test_stat_record_script used default
output which triggers a bug when sending metrics. As this isn't
relevant to the test switch to using named software events.

Update the match in test_hybrid as the cycles event is now cpu-cycles
to workaround potential ARM issues.

Signed-off-by: Ian Rogers 
Signed-off-by: Namhyung Kim

perf test stat: Additional topdown grouping tests

2025-03-12T02:05:04+00:00

Add a loop and helper function to avoid repetition, the loop uses
arrays so switch the shell to bash. Add additional topdown group tests
where a topdown event needs to be moved beyond others and the slots
event isn't first in the target group. This replicates issues that
occur on hybrid systems where the other events are for the cpu_atom
PMU. Test with both PMU and software events. Place the slots event
later in the event list.

Signed-off-by: Ian Rogers 
Link: https://lore.kernel.org/r/20250307023906.1135613-5-irogers@google.com
Signed-off-by: Namhyung Kim

perf test stat: Avoid hybrid assumption when virtualized

2025-01-14T17:57:19+00:00

The cycles event will fallback to task-clock in the hybrid test when
running virtualized. Change the test to not fail for this.

Fixes: 65d11821910bd910 ("perf test: Add a test for default perf stat command")
Reviewed-by: James Clark 
Signed-off-by: Ian Rogers 
Acked-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Kan Liang 
Cc: Mark Rutland 
Cc: Peter Zijlstra 
Link: https://lore.kernel.org/r/20241212173354.9860-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo