[PATCH 3/3] perf bench syscall: Add execve syscall benchmark

[Tiezhu Yang <yangtiezhu@loongson.cn>]

This commit adds the execve syscall benchmark, more syscall
benchmarks can be added in the future.

Here are the test results:

  [loongson@linux perf]$ ./perf bench syscall

          # List of available benchmarks for collection 'syscall':

           basic: Benchmark for basic getppid(2) calls
           close: Benchmark for close(2) calls
          execve: Benchmark for execve(2) calls
             all: Run all syscall benchmarks

  [loongson@linux perf]$ ./perf bench syscall execve
  # Running 'syscall/execve' benchmark:
  # Executed 10000 execve() calls
       Total time: 4.827 [sec]

       482.761800 usecs/op
             2071 ops/sec
  [loongson@linux perf]$ ./perf bench syscall all
  # Running syscall/basic benchmark...
  # Executed 10000000 getppid() calls
       Total time: 1.956 [sec]

         0.195692 usecs/op
          5110065 ops/sec

  # Running syscall/close benchmark...
  # Executed 10000000 close() calls
       Total time: 6.306 [sec]

         0.630692 usecs/op
          1585558 ops/sec

  # Running syscall/execve benchmark...
  # Executed 10000 execve() calls
       Total time: 4.842 [sec]

       484.299500 usecs/op
             2064 ops/sec

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 tools/perf/bench/bench.h   |  1 +
 tools/perf/bench/syscall.c | 36 ++++++++++++++++++++++++++++++++++++
 tools/perf/builtin-bench.c |  1 +
 3 files changed, 38 insertions(+)

diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h
index 916cd47..6ca3327 100644
--- a/tools/perf/bench/bench.h
+++ b/tools/perf/bench/bench.h
@@ -35,6 +35,7 @@ int bench_sched_messaging(int argc, const char **argv);
 int bench_sched_pipe(int argc, const char **argv);
 int bench_syscall_basic(int argc, const char **argv);
 int bench_syscall_close(int argc, const char **argv);
+int bench_syscall_execve(int argc, const char **argv);
 int bench_mem_memcpy(int argc, const char **argv);
 int bench_mem_memset(int argc, const char **argv);
 int bench_mem_find_bit(int argc, const char **argv);
diff --git a/tools/perf/bench/syscall.c b/tools/perf/bench/syscall.c
index 058394b..c8f8bee 100644
--- a/tools/perf/bench/syscall.c
+++ b/tools/perf/bench/syscall.c
@@ -14,6 +14,7 @@
 #include <sys/time.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
+#include <sys/wait.h>
 #include <unistd.h>
 #include <stdlib.h>
 
@@ -30,6 +31,27 @@ static const char * const bench_syscall_usage[] = {
 	NULL
 };
 
+static void test_execve(void)
+{
+	const char *pathname = "/bin/true";
+	char *const argv[] = { (char *)pathname, NULL };
+	pid_t pid = fork();
+
+	if (pid < 0) {
+		fprintf(stderr, "fork failed\n");
+		exit(1);
+	} else if (pid == 0) {
+		execve(pathname, argv, NULL);
+		fprintf(stderr, "execve /bin/true failed\n");
+		exit(1);
+	} else {
+		if (waitpid(pid, NULL, 0) < 0) {
+			fprintf(stderr, "waitpid failed\n");
+			exit(1);
+		}
+	}
+}
+
 static int bench_syscall_common(int argc, const char **argv, int syscall)
 {
 	struct timeval start, stop, diff;
@@ -49,6 +71,12 @@ static int bench_syscall_common(int argc, const char **argv, int syscall)
 		case __NR_close:
 			close(dup(0));
 			break;
+		case __NR_execve:
+			test_execve();
+			/* Only loop 10000 times to save time */
+			if (i == 10000)
+				loops = 10000;
+			break;
 		default:
 			break;
 		}
@@ -64,6 +92,9 @@ static int bench_syscall_common(int argc, const char **argv, int syscall)
 	case __NR_close:
 		name = "close()";
 		break;
+	case __NR_execve:
+		name = "execve()";
+		break;
 	default:
 		break;
 	}
@@ -111,3 +142,8 @@ int bench_syscall_close(int argc, const char **argv)
 {
 	return bench_syscall_common(argc, argv, __NR_close);
 }
+
+int bench_syscall_execve(int argc, const char **argv)
+{
+	return bench_syscall_common(argc, argv, __NR_execve);
+}
diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c
index b63c711..6f9ff75 100644
--- a/tools/perf/builtin-bench.c
+++ b/tools/perf/builtin-bench.c
@@ -53,6 +53,7 @@ static struct bench sched_benchmarks[] = {
 static struct bench syscall_benchmarks[] = {
 	{ "basic",	"Benchmark for basic getppid(2) calls",		bench_syscall_basic	},
 	{ "close",	"Benchmark for close(2) calls",			bench_syscall_close	},
+	{ "execve",	"Benchmark for execve(2) calls",		bench_syscall_execve	},
 	{ "all",	"Run all syscall benchmarks",			NULL			},
 	{ NULL,		NULL,						NULL			},
 };
-- 
2.1.0