linux-kernel - Re: [PATCH v2 4/4] perf test: Add user space counter reading tests

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Date:   Thu, 9 Jun 2022 11:10:55 +0530
From:   kajoljain <kjain@...ux.ibm.com>
To:     Ian Rogers <irogers@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Rob Herring <robh@...nel.org>
Cc:     Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH v2 4/4] perf test: Add user space counter reading tests

Patch looks fine to me.

Reviewed-By: Kajol Jain<kjain@...ux.ibm.com>

Thanks,
Kajol Jain

On 6/9/22 10:53, Ian Rogers wrote:
> These tests are based on test_stat_user_read in
> tools/lib/perf/tests/test-evsel.c. The tests are modified to skip if
> perf_event_open fails or rdpmc isn't supported.
> 
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  tools/perf/tests/mmap-basic.c | 127 +++++++++++++++++++++++++++++++++-
>  1 file changed, 126 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/mmap-basic.c b/tools/perf/tests/mmap-basic.c
> index 30bbe144648a..dfb6173b2a82 100644
> --- a/tools/perf/tests/mmap-basic.c
> +++ b/tools/perf/tests/mmap-basic.c
> @@ -170,14 +170,139 @@ static int test__basic_mmap(struct test_suite *test __maybe_unused, int subtest
>  	return err;
>  }
>  
> +static int test_stat_user_read(int event)
> +{
> +	struct perf_counts_values counts = { .val = 0 };
> +	struct perf_thread_map *threads;
> +	struct perf_evsel *evsel;
> +	struct perf_event_mmap_page *pc;
> +	struct perf_event_attr attr = {
> +		.type	= PERF_TYPE_HARDWARE,
> +		.config	= event,
> +#ifdef __aarch64__
> +		.config1 = 0x2,		/* Request user access */
> +#endif
> +	};
> +	int err, i, ret = TEST_FAIL;
> +	bool opened = false, mapped = false;
> +
> +	threads = perf_thread_map__new_dummy();
> +	TEST_ASSERT_VAL("failed to create threads", threads);
> +
> +	perf_thread_map__set_pid(threads, 0, 0);
> +
> +	evsel = perf_evsel__new(&attr);
> +	TEST_ASSERT_VAL("failed to create evsel", evsel);
> +
> +	err = perf_evsel__open(evsel, NULL, threads);
> +	if (err) {
> +		pr_err("failed to open evsel: %s\n", strerror(-err));
> +		ret = TEST_SKIP;
> +		goto out;
> +	}
> +	opened = true;
> +
> +	err = perf_evsel__mmap(evsel, 0);
> +	if (err) {
> +		pr_err("failed to mmap evsel: %s\n", strerror(-err));
> +		goto out;
> +	}
> +	mapped = true;
> +
> +	pc = perf_evsel__mmap_base(evsel, 0, 0);
> +	if (!pc) {
> +		pr_err("failed to get mmapped address\n");
> +		goto out;
> +	}
> +
> +	if (!pc->cap_user_rdpmc || !pc->index) {
> +		pr_err("userspace counter access not %s\n",
> +			!pc->cap_user_rdpmc ? "supported" : "enabled");
> +		ret = TEST_SKIP;
> +		goto out;
> +	}
> +	if (pc->pmc_width < 32) {
> +		pr_err("userspace counter width not set (%d)\n", pc->pmc_width);
> +		goto out;
> +	}
> +
> +	perf_evsel__read(evsel, 0, 0, &counts);
> +	if (counts.val == 0) {
> +		pr_err("failed to read value for evsel\n");
> +		goto out;
> +	}
> +
> +	for (i = 0; i < 5; i++) {
> +		volatile int count = 0x10000 << i;
> +		__u64 start, end, last = 0;
> +
> +		pr_debug("\tloop = %u, ", count);
> +
> +		perf_evsel__read(evsel, 0, 0, &counts);
> +		start = counts.val;
> +
> +		while (count--) ;
> +
> +		perf_evsel__read(evsel, 0, 0, &counts);
> +		end = counts.val;
> +
> +		if ((end - start) < last) {
> +			pr_err("invalid counter data: end=%llu start=%llu last= %llu\n",
> +				end, start, last);
> +			goto out;
> +		}
> +		last = end - start;
> +		pr_debug("count = %llu\n", end - start);
> +	}
> +	ret = TEST_OK;
> +
> +out:
> +	if (mapped)
> +		perf_evsel__munmap(evsel);
> +	if (opened)
> +		perf_evsel__close(evsel);
> +	perf_evsel__delete(evsel);
> +
> +	perf_thread_map__put(threads);
> +	return ret;
> +}
> +
> +static int test__mmap_user_read_instr(struct test_suite *test __maybe_unused,
> +				      int subtest __maybe_unused)
> +{
> +	return test_stat_user_read(PERF_COUNT_HW_INSTRUCTIONS);
> +}
> +
> +static int test__mmap_user_read_cycles(struct test_suite *test __maybe_unused,
> +				       int subtest __maybe_unused)
> +{
> +	return test_stat_user_read(PERF_COUNT_HW_CPU_CYCLES);
> +}
> +
>  static struct test_case tests__basic_mmap[] = {
>  	TEST_CASE_REASON("Read samples using the mmap interface",
>  			 basic_mmap,
>  			 "permissions"),
> +	TEST_CASE_REASON("User space counter reading of instructions",
> +			 mmap_user_read_instr,
> +#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
> +			 "permissions"
> +#else
> +			 "unsupported"
> +#endif
> +		),
> +	TEST_CASE_REASON("User space counter reading of cycles",
> +			 mmap_user_read_cycles,
> +#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
> +			 "permissions"
> +#else
> +			 "unsupported"
> +#endif
> +		),
>  	{	.name = NULL, }
>  };
>  
>  struct test_suite suite__basic_mmap = {
> -	.desc = "Read samples using the mmap interface",
> +	.desc = "mmap interface tests",
>  	.test_cases = tests__basic_mmap,
>  };