From ea426585d663b462d93fc0546ce01119504dee4b Mon Sep 17 00:00:00 2001
From: Jeff Layton <jlayton@redhat.com>
Date: Tue, 4 Jun 2013 15:10:51 -0400
Subject: [PATCH] perf2: add stats gathering

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 perf2.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 55 insertions(+), 7 deletions(-)

diff --git a/perf2.c b/perf2.c
index 5b0ae85..6c04738 100644
--- a/perf2.c
+++ b/perf2.c
@@ -8,6 +8,10 @@
  * locks are generally uncontended.
  */
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif /* HAVE_CONFIG_H */
+
 #include <stdio.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -17,17 +21,24 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <stdlib.h>
+#include <time.h>
+#include <sys/mman.h>
+
+#include "timespec.h"
 
 #define NRPROC (128)
 #define NRLOCK (10240)
 
+static struct timespec *diff;
+
 static int
-lockunlock(int nrlock)
+lockunlock(int nrlock, struct timespec *slot)
 {
 	int fd, i, ret;
 	struct flock lck = { .l_whence = SEEK_SET };
 	pid_t pid = getpid();
 	char name[10]; /* big enough for pid_t in hex + NULL */
+	struct timespec start, end;
 
 	ret = snprintf(name, sizeof(name), "%x", pid);
 	if (ret >= (int)sizeof(name)) {
@@ -41,6 +52,12 @@ lockunlock(int nrlock)
 		return fd;
 	}
 
+	ret = clock_gettime(CLOCK_MONOTONIC_RAW, &start);
+	if (ret) {
+		perror("clock_gettime");
+		return ret;
+	}
+
 	for (i = 0; i < nrlock; ++i) {
 		lck.l_type = F_WRLCK;
 		ret = fcntl(fd, F_SETLKW, &lck);
@@ -55,7 +72,15 @@ lockunlock(int nrlock)
 			break;
 		}
 	}
+
+	ret = clock_gettime(CLOCK_MONOTONIC_RAW, &end);
+	if (ret) {
+		perror("clock_gettime");
+		return ret;
+	}
+
 	close(fd);
+	*slot = timespec_sub(end, start);
 	return ret;
 }
 
@@ -68,11 +93,13 @@ usage(char *prog)
 int
 main(int argc, char **argv)
 {
-	int i, opt;
+	int i, opt, valid = 0;
 	int nproc = NRPROC;
 	int nlock = NRLOCK;
 	pid_t *pids;
 	char *dirname;
+	struct timespec total = { .tv_sec = 0,
+				  .tv_nsec = 0 };
 
 	while ((opt = getopt(argc, argv, "l:n:")) != -1) {
 		switch (opt) {
@@ -110,18 +137,39 @@ main(int argc, char **argv)
 		return 1;
 	}
 
+	diff = mmap(0, nproc * sizeof(*diff), PROT_READ | PROT_WRITE,
+			MAP_ANONYMOUS | MAP_SHARED, -1, 0);
+	if (diff == (struct timespec *)-1) {
+		fprintf(stderr, "Unable to allocate timespec array!");
+		return 1;
+	}
+
 	for (i = 0; i < nproc; ++i) {
 		pids[i] = fork();
 		if (!pids[i])
-			return lockunlock(nlock);
+			return lockunlock(nlock, &diff[i]);
 	}
 
 	for (i = 0; i < nproc; ++i) {
-		if (pids[i] < 0)
-			printf("process %d failed to fork\n", i);
-		else
-			waitpid(-1, NULL, 0);
+		int status;
+
+		if (pids[i] < 0) {
+			fprintf(stderr, "process %d failed to fork\n", i);
+			continue;
+		}
+		if (waitpid(pids[i], &status, 0) < 0) {
+			fprintf(stderr, "unable to reap pid %d\n", pids[i]);
+			continue;
+		}
+		if (!WIFEXITED(status) || WEXITSTATUS(status)) {
+			fprintf(stderr, "pid %d exited abnormally(0x%x)\n", pids[i],status);
+			continue;
+		}
+		total = timespec_add(total, diff[i]);
+		++valid;
 	}
 
+	printf("Number of processes that ran normally:\t%d\n", valid);
+	printf("Total time spent in lock/unlock code:\t%ld.%ld\n", total.tv_sec, total.tv_nsec);
 	return 0;
 }
-- 
2.34.1