tools/perf/tests/perf-time-to-tsc.c

Source file repositories/reference/linux-study-clean/tools/perf/tests/perf-time-to-tsc.c

File Facts

System
Linux kernel
Corpus path
tools/perf/tests/perf-time-to-tsc.c
Extension
.c
Size
5606 bytes
Lines
222
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

if (ret == -EOPNOTSUPP) {
			pr_debug("perf_read_tsc_conversion is not supported in current kernel\n");
			err = TEST_SKIP;
		}
		goto out_err;
	}

	evlist__enable(evlist);

	comm1 = "Test COMM 1";
	CHECK__(prctl(PR_SET_NAME, (unsigned long)comm1, 0, 0, 0));

	test_tsc = rdtsc();

	comm2 = "Test COMM 2";
	CHECK__(prctl(PR_SET_NAME, (unsigned long)comm2, 0, 0, 0));

	evlist__disable(evlist);

	for (i = 0; i < evlist->core.nr_mmaps; i++) {
		md = &evlist->mmap[i];
		if (perf_mmap__read_init(&md->core) < 0)
			continue;

		while ((event = perf_mmap__read_event(&md->core)) != NULL) {
			struct perf_sample sample;

			perf_sample__init(&sample, /*all=*/false);
			if (event->header.type != PERF_RECORD_COMM ||
			    (pid_t)event->comm.pid != getpid() ||
			    (pid_t)event->comm.tid != getpid())
				goto next_event;

			if (strcmp(event->comm.comm, comm1) == 0) {
				CHECK_NOT_NULL__(evsel = evlist__event2evsel(evlist, event));
				CHECK__(evsel__parse_sample(evsel, event, &sample));
				comm1_time = sample.time;
			}
			if (strcmp(event->comm.comm, comm2) == 0) {
				CHECK_NOT_NULL__(evsel = evlist__event2evsel(evlist, event));
				CHECK__(evsel__parse_sample(evsel, event, &sample));
				comm2_time = sample.time;
			}
next_event:
			perf_mmap__consume(&md->core);
			perf_sample__exit(&sample);
		}
		perf_mmap__read_done(&md->core);
	}

	if (!comm1_time || !comm2_time)
		goto out_err;

	test_time = tsc_to_perf_time(test_tsc, &tc);
	comm1_tsc = perf_time_to_tsc(comm1_time, &tc);
	comm2_tsc = perf_time_to_tsc(comm2_time, &tc);

	pr_debug("1st event perf time %"PRIu64" tsc %"PRIu64"\n",
		 comm1_time, comm1_tsc);
	pr_debug("rdtsc          time %"PRIu64" tsc %"PRIu64"\n",
		 test_time, test_tsc);
	pr_debug("2nd event perf time %"PRIu64" tsc %"PRIu64"\n",
		 comm2_time, comm2_tsc);

	if (test_time <= comm1_time ||
	    test_time >= comm2_time)
		goto out_err;

	if (test_tsc <= comm1_tsc ||
	    test_tsc >= comm2_tsc)
		goto out_err;

	err = TEST_OK;

out_err:
	evlist__delete(evlist);
	perf_cpu_map__put(cpus);
	perf_thread_map__put(threads);
	return err;
}

static struct test_case time_to_tsc_tests[] = {
	TEST_CASE_REASON("TSC support", tsc_is_supported,
			 "This architecture does not support"),
	TEST_CASE_REASON("Perf time to TSC", perf_time_to_tsc,
			 "perf_read_tsc_conversion is not supported"),
	{ .name = NULL, }
};

struct test_suite suite__perf_time_to_tsc = {

Annotation

Implementation Notes