perf test: Add -w/--workload option

The -w/--workload option is to run a simple workload used by testing.
This adds a basic framework to run the workloads and 'noploop' workload
as an example.

$ perf test -w noploop

The noploop does a loop doing nothing (NOP) for a second by default.
It can have an optional argument to specify the time in seconds.

Signed-off-by: Namhyung Kim <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Athira Jajeev <[e-mail]>
Cc: German Gomez <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Zhengjun Xing <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/Build

···
 CFLAGS_attr.o         += -DBINDIR="BUILD_STR($(bindir_SQ))" -DPYTHON="BUILD_STR($(PYTHON_WORD))"
 CFLAGS_python-use.o   += -DPYTHONPATH="BUILD_STR($(OUTPUT)python)" -DPYTHON="BUILD_STR($(PYTHON_WORD))"
 CFLAGS_dwarf-unwind.o += -fno-optimize-sibling-calls
+
+perf-y += workloads/

tools/perf/tests/builtin-test.c

···
 	arch_tests,
 };
 
+static struct test_workload *workloads[] = {
+	&workload__noploop,
+};
+
 static int num_subtests(const struct test_suite *t)
 {
 	int num;
···
 	return 0;
 }
 
+static int run_workload(const char *work, int argc, const char **argv)
+{
+	unsigned int i = 0;
+	struct test_workload *twl;
+
+	for (i = 0; i < ARRAY_SIZE(workloads); i++) {
+		twl = workloads[i];
+		if (!strcmp(twl->name, work))
+			return twl->func(argc, argv);
+	}
+
+	pr_info("No workload found: %s\n", work);
+	return -1;
+}
+
 int cmd_test(int argc, const char **argv)
 {
 	const char *test_usage[] = {
···
 	NULL,
 	};
 	const char *skip = NULL;
+	const char *workload = NULL;
 	const struct option test_options[] = {
 	OPT_STRING('s', "skip", &skip, "tests", "tests to skip"),
 	OPT_INCR('v', "verbose", &verbose,
 		    "be more verbose (show symbol address, etc)"),
 	OPT_BOOLEAN('F', "dont-fork", &dont_fork,
 		    "Do not fork for testcase"),
+	OPT_STRING('w', "workload", &workload, "work", "workload to run for testing"),
 	OPT_END()
 	};
 	const char * const test_subcommands[] = { "list", NULL };
···
 	argc = parse_options_subcommand(argc, argv, test_options, test_subcommands, test_usage, 0);
 	if (argc >= 1 && !strcmp(argv[0], "list"))
 		return perf_test__list(argc - 1, argv + 1);
+
+	if (workload)
+		return run_workload(workload, argc, argv);
 
 	symbol_conf.priv_size = sizeof(int);
 	symbol_conf.sort_by_name = true;

tools/perf/tests/tests.h

···
 DECLARE_SUITE(vectors_page);
 #endif
 
+/*
+ * Define test workloads to be used in test suites.
+ */
+typedef int (*workload_fnptr)(int argc, const char **argv);
+
+struct test_workload {
+	const char	*name;
+	workload_fnptr	func;
+};
+
+#define DECLARE_WORKLOAD(work) \
+	extern struct test_workload workload__##work
+
+#define DEFINE_WORKLOAD(work) \
+struct test_workload workload__##work = {	\
+	.name = #work,				\
+	.func = work,				\
+}
+
+/* The list of test workloads */
+DECLARE_WORKLOAD(noploop);
+
 #endif /* TESTS_H */

tools/perf/tests/workloads/Build

···
+# SPDX-License-Identifier: GPL-2.0
+
+perf-y += noploop.o

tools/perf/tests/workloads/noploop.c

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+#include <linux/compiler.h>
+#include "../tests.h"
+
+static volatile sig_atomic_t done;
+
+static void sighandler(int sig __maybe_unused)
+{
+	done = 1;
+}
+
+static int noploop(int argc, const char **argv)
+{
+	int sec = 1;
+
+	if (argc > 0)
+		sec = atoi(argv[0]);
+
+	signal(SIGINT, sighandler);
+	signal(SIGALRM, sighandler);
+	alarm(sec);
+
+	while (!done)
+		continue;
+
+	return 0;
+}
+
+DEFINE_WORKLOAD(noploop);