perf test: Display number of active running tests

Before polling or sleeping to wait for a test to complete, print out
": Running (<num> active)" where the number of active tests is
determined by iterating over the tests and seeing which return false
for check_if_command_finished. The line erasing and printing out only
occur if the number of runnings tests changes to avoid the line
flickering excessively. Knowing tests are running allows a user to
know a test is running and in parallel mode how many of the tests are
waiting to complete. If color mode is disabled then avoid displaying
the "Running" message as deleting the line isn't reliable.

Tested-by: James Clark <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Cc: Colin Ian King <[e-mail]>
Cc: Howard Chu <[e-mail]>
Cc: Weilin Wang <[e-mail]>
Cc: Ilya Leoshkevich <[e-mail]>
Cc: Thomas Richter <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Dapeng Mi <[e-mail]>
Cc: Athira Jajeev <[e-mail]>
Cc: Michael Petlan <[e-mail]>
Cc: Veronika Molnarova <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/tests/builtin-test.c

···
 	return -err;
 }
 
-static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width)
+#define TEST_RUNNING -3
+
+static int print_test_result(struct test_suite *t, int i, int subtest, int result, int width,
+			     int running)
 {
 	if (has_subtests(t)) {
 		int subw = width > 2 ? width - 2 : width;
···
 		pr_info("%3d: %-*s:", i + 1, width, test_description(t, subtest));
 
 	switch (result) {
+	case TEST_RUNNING:
+		color_fprintf(stderr, PERF_COLOR_YELLOW, " Running (%d active)\n", running);
+		break;
 	case TEST_OK:
 		pr_info(" Ok\n");
 		break;
···
 	return 0;
 }
 
-static int finish_test(struct child_test *child_test, int width)
+static int finish_test(struct child_test **child_tests, int running_test, int child_test_num,
+		       int width)
 {
+	struct child_test *child_test = child_tests[running_test];
 	struct test_suite *t = child_test->test;
 	int i = child_test->test_num;
 	int subi = child_test->subtest;
 	int err = child_test->process.err;
-	bool err_done = err <= 0;
+	bool err_done = false;
 	struct strbuf err_output = STRBUF_INIT;
+	int last_running = -1;
 	int ret;
 
 	/*
···
 	 * Busy loop reading from the child's stdout/stderr that are set to be
 	 * non-blocking until EOF.
 	 */
-	if (!err_done)
+	if (err > 0)
 		fcntl(err, F_SETFL, O_NONBLOCK);
 	if (verbose > 1) {
 		if (has_subtests(t))
···
 			  .events = POLLIN | POLLERR | POLLHUP | POLLNVAL,
 			},
 		};
-		char buf[512];
-		ssize_t len;
+		if (perf_use_color_default) {
+			int running = 0;
 
-		/* Poll to avoid excessive spinning, timeout set for 100ms. */
-		poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
-		if (!err_done && pfds[0].revents) {
-			errno = 0;
-			len = read(err, buf, sizeof(buf) - 1);
-
-			if (len <= 0) {
-				err_done = errno != EAGAIN;
-			} else {
-				buf[len] = '\0';
-				if (verbose > 1)
-					fprintf(stdout, "%s", buf);
-				else
-					strbuf_addstr(&err_output, buf);
+			for (int y = running_test; y < child_test_num; y++) {
+				if (check_if_command_finished(&child_tests[y]->process) == 0)
+					running++;
+			}
+			if (running != last_running) {
+				if (last_running != -1) {
+					/*
+					 * Erase "Running (.. active)" line
+					 * printed before poll/sleep.
+					 */
+					fprintf(debug_file(), PERF_COLOR_DELETE_LINE);
+				}
+				print_test_result(t, i, subi, TEST_RUNNING, width, running);
+				last_running = running;
 			}
 		}
+
+		err_done = true;
+		if (err <= 0) {
+			/* No child stderr to poll, sleep for 10ms for child to complete. */
+			usleep(10 * 1000);
+		} else {
+			/* Poll to avoid excessive spinning, timeout set for 100ms. */
+			poll(pfds, ARRAY_SIZE(pfds), /*timeout=*/100);
+			if (pfds[0].revents) {
+				char buf[512];
+				ssize_t len;
+
+				len = read(err, buf, sizeof(buf) - 1);
+
+				if (len > 0) {
+					err_done = false;
+					buf[len] = '\0';
+					strbuf_addstr(&err_output, buf);
+				}
+			}
+		}
+		if (err_done)
+			err_done = check_if_command_finished(&child_test->process);
+	}
+	if (perf_use_color_default && last_running != -1) {
+		/* Erase "Running (.. active)" line printed before poll/sleep. */
+		fprintf(debug_file(), PERF_COLOR_DELETE_LINE);
 	}
 	/* Clean up child process. */
 	ret = finish_command(&child_test->process);
-	if (verbose == 1 && ret == TEST_FAIL) {
-		/* Add header for test that was skipped above. */
-		if (has_subtests(t))
-			pr_info("%3d.%1d: %s:\n", i + 1, subi + 1, test_description(t, subi));
-		else
-			pr_info("%3d: %s:\n", i + 1, test_description(t, -1));
+	if (verbose > 1 || (verbose == 1 && ret == TEST_FAIL))
 		fprintf(stderr, "%s", err_output.buf);
-	}
+
 	strbuf_release(&err_output);
-	print_test_result(t, i, subi, ret, width);
+	print_test_result(t, i, subi, ret, width, /*running=*/0);
 	if (err > 0)
 		close(err);
 	return 0;
···
 		pr_debug("--- start ---\n");
 		err = test_function(test, subi)(test, subi);
 		pr_debug("---- end ----\n");
-		print_test_result(test, i, subi, err, width);
+		print_test_result(test, i, subi, err, width, /*running=*/0);
 		return 0;
 	}
 
···
 	err = start_command(&(*child)->process);
 	if (err || !sequential)
 		return  err;
-	return finish_test(*child, width);
+	return finish_test(child, /*running_test=*/0, /*child_test_num=*/1, width);
 }
 
 #define for_each_test(j, k, t)					\
···
 	}
 	for (i = 0; i < child_test_num; i++) {
 		if (!sequential) {
-			int ret  = finish_test(child_tests[i], width);
+			int ret  = finish_test(child_tests, i, child_test_num, width);
 
 			if (ret)
 				return ret;

tools/perf/util/color.h

···
 #define MIN_GREEN	0.5
 #define MIN_RED		5.0
 
+#define PERF_COLOR_DELETE_LINE	"\033[A\33[2K\r"
 /*
  * This variable stores the value of color.ui
  */