Date:   Wed, 14 Sep 2022 11:25:07 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, Ian Rogers <irogers@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-perf-users <linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH 00/11] perf test: test_intel_pt.sh: Add per-thread test

On 13/09/22 20:41, Namhyung Kim wrote:
> On Mon, Sep 12, 2022 at 1:34 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>>
>> Hi
>>
>> Here is a new per-thread test for the test_intel_pt.sh test script.
>>
>> The first 9 patches are tidy-ups for the script, mostly based on results
>> from the shellcheck utility.
>>
>> The 10th patch adds debug prints that the script will capture to help
>> verify correct operation.
>>
>> The final patch actually adds the new test.
>>
>>
>> Adrian Hunter (11):
>>       perf test: test_intel_pt.sh: Add cleanup function
>>       perf test: test_intel_pt.sh: Use a temp directory
>>       perf test: test_intel_pt.sh: Fix redirection
>>       perf test: test_intel_pt.sh: Stop using expr
>>       perf test: test_intel_pt.sh: Stop using backticks
>>       perf test: test_intel_pt.sh: Use grep -c instead of grep plus wc -l
>>       perf test: test_intel_pt.sh: Use quotes around variable expansion
>>       perf test: test_intel_pt.sh: Fix return checking
>>       perf test: test_intel_pt.sh: Add more output in preparation for more tests
>>       perf tools: Add debug messages and comments for testing
>>       perf test: test_intel_pt.sh: Add per-thread test
> 
> I don't think I understood all the black magic in patch 11. :)

It is not that bad :-)

Consider the output from the test:


	$ perf test -v " intel pt"
	Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
	102: Miscellaneous Intel PT testing                                  :
	--- start ---
	test child forked, pid 155646
<SNIP>
	--- Test per-thread recording ---
	Workload PIDs are 155669 and 155670
	perf PID is 155681
	Waiting for "perf record has started" message
	OK
	pid 155669 cpu -1 fd 5 : sys_perf_event_open: pid 155669  cpu -1 group_fd -1  flags 0x8 = 5

awk has matched the debug message and determined the values for pid, cpu and fd

	pid 155673 cpu -1 fd 6 : sys_perf_event_open: pid 155673  cpu -1 group_fd -1  flags 0x8 = 6
	pid 155670 cpu -1 fd 7 : sys_perf_event_open: pid 155670  cpu -1 group_fd -1  flags 0x8 = 7
	pid 155672 cpu -1 fd 8 : sys_perf_event_open: pid 155672  cpu -1 group_fd -1  flags 0x8 = 8
	pid 155669 cpu -1 fd 9 : sys_perf_event_open: pid 155669  cpu -1 group_fd -1  flags 0x8 = 9
	pid 155673 cpu -1 fd 10 : sys_perf_event_open: pid 155673  cpu -1 group_fd -1  flags 0x8 = 10
	pid 155670 cpu -1 fd 11 : sys_perf_event_open: pid 155670  cpu -1 group_fd -1  flags 0x8 = 11
	pid 155672 cpu -1 fd 12 : sys_perf_event_open: pid 155672  cpu -1 group_fd -1  flags 0x8 = 12
	fd 5 : idx 0: mmapping fd 5
	
awk has matched the debug message and determined the values for fd
	
	fd 9 fd_to 5 : idx 0: set output fd 9 -> 5
	
awk has matched the debug message and determined the values for fd and fd_to

	fd 6 : idx 1: mmapping fd 6
	fd 10 fd_to 6 : idx 1: set output fd 10 -> 6
	fd 7 : idx 2: mmapping fd 7
	fd 11 fd_to 7 : idx 2: set output fd 11 -> 7
	fd 8 : idx 3: mmapping fd 8
	fd 12 fd_to 8 : idx 3: set output fd 12 -> 8
	Checking 8 fds

Now awk is checking:
- every fd is mmapped or set-output
- there is 1 mmap per unique pid
- there is 1 mmap per unique cpu
- there are the right number of different pids
i.e.
	END {
		print "Checking " length(fd_array) " fds"
		for (fd in fd_array) {
			if (fd in mmap_array) {
				pid = pid_array[fd]
				if (pid != -1) {
					if (pid in pids) {
						print "More than 1 mmap for PID " pid
						exit 1
					}
					pids[pid] = 1
				}
				cpu = cpu_array[fd]
				if (cpu != -1) {
					if (cpu in cpus) {
						print "More than 1 mmap for CPU " cpu
						exit 1
					}
					cpus[cpu] = 1
				}
			} else if (!(fd in set_output_array)) {
				print "No mmap for fd " fd
				exit 1
			}
		}
		n = length(pids)
		if (n != thread_cnt) {
			print "Expected " thread_cnt " per-thread mmaps - found " n
			exit 1
		}
	}

> At least we can move some helper functions to the lib and
> reuse them in other tests.  I'll test that later..
> 
> So for patch 01-10,
> 
> Acked-by: Namhyung Kim <namhyung@...nel.org>
> 
> Thanks,
> Namhyung
> 
> 
>>
>>  tools/lib/perf/evlist.c                 |   2 +
>>  tools/perf/builtin-record.c             |   8 +
>>  tools/perf/tests/shell/test_intel_pt.sh | 307 ++++++++++++++++++++++++++++++--
>>  tools/perf/util/evsel.c                 |   2 +
>>  4 files changed, 304 insertions(+), 15 deletions(-)
>>
>>
>> Regards
>> Adrian

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