Add number of processes options

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

1 files changed, 88 insertions, 44 deletions

diff --git a/iolatsimu.c b/iolatsimu.c
index 2d8badc..119e844 100644
--- a/iolatsimu.c
+++ b/iolatsimu.c
@@ -3,6 +3,8 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 #include <fcntl.h>
 
 #include "list.h"
@@ -44,6 +46,7 @@
  *
  */
 #define BUCKET_INTERVAL 500
+static int bucket_interval = BUCKET_INTERVAL;
 
 /*
  * Number of successive hits for the same bucket. That is the thresold
@@ -148,7 +151,9 @@ static int bucket_guessed_index(void)
 		 * more weight the next one. If a bucket is in the process
 		 * of being hit several times, take it into account.
 		 */
-		score = bucket->hits / (1 << weight);
+		score = bucket->hits / ((2 * weight) + 1);
+
+		weight++;
 
 		if (score < score_max)
 			continue;
@@ -165,7 +170,7 @@ static int bucket_guessed_index(void)
  */
 static int bucket_index(int latency)
 {
-	return latency / BUCKET_INTERVAL;
+	return latency / bucket_interval;
 }
 
 /*
@@ -228,12 +233,13 @@ static void bucket_show(void)
 		
 		bucket = list_entry(list, struct bucket, list);
 
-		printf("bucket %d: %d\n",
+		printf("[pid %d] bucket %d: %d\n", getpid(),
 		       bucket->index, bucket->hits);
 	}
 
-	printf("Number of correct predictions: %d/%d (%.2f%%)\n",
-	       success, nrlatency, ((float)success / (float)nrlatency) * 100.0);
+	printf("[pid %d] Number of correct predictions: %d/%d (%.2f%%)\n",
+	       getpid(), success, nrlatency,
+	       ((float)success / (float)nrlatency) * 100.0);
 }
 
 /*
@@ -246,6 +252,7 @@ static void bucket_show(void)
 
 #define NROFFSET 256
 #define PAGESIZE 16384
+// #define PAGESIZE 1048576 16384
 
 static char buffer[PAGESIZE];
 
@@ -265,13 +272,18 @@ void write_file(int fd)
 int mktempfile(const char *dirname)
 {
 	char *name;
+	int fd;
 
-	if (asprintf(&name, "%s/XXXXXX", dirname) < 0) {
+	if (asprintf(&name, "%s/iosimul-XXXXXX", dirname) < 0) {
 		perror("asprintf");
 		return -1;
 	}
 
-	return mkstemp(name);
+	fd = mkstemp(name);
+	if (fd >= 0)
+		unlink(name);
+
+	return fd;
 }
 
 int main(int argc, char *argv[])
@@ -281,65 +293,97 @@ int main(int argc, char *argv[])
 	int i;
 	unsigned long int latency;
 	const char *dirname = "/tmp";
-	int fd;
+	int fd, pid;
+	int nrchild = 1;
 
 	/* 
 	 * Optionnally we can specify the directory to test the
-	 * latencies
+	 * latencies, ...
 	 */
-	if (argc == 2)
+	if (argc > 1)
 		dirname = argv[1];
 
 	/*
-	 * Make temporary file, we don't want to pollute the file system
-	 * with big files if this program crashes
+	 * ... the bucket interval, ...
 	 */
-	fd = mktempfile(dirname);
-	if (fd < 0) {
-		perror("mktempfile");
-		return -1;
-	}
-
-	write_file(fd);
+	if (argc > 2)
+		bucket_interval = atoi(argv[2]);
 
 	/*
-	 * Initialize the random seed with the number of current usec.
-	 * This random value will be used to access the file randomly, no
-	 * sequential accesses which can be optimized by the hardware
+	 * ... the number of processes
 	 */
-	gettimeofday(&begin, NULL);
-	srandom(begin.tv_usec);
+	if (argc > 3)
+		nrchild = atoi(argv[3]);
 
-	for (i = 0; i < 10000; i++) {
+	for (i = 0; i < nrchild; i++) {
 
-		/*
-		 * Compute the offset address to read from
-		 */
-		offset = (random() % NROFFSET) * PAGESIZE;
+		pid = fork();
 
-		/*
-		 * man posix_fadvise
-		 */
-		posix_fadvise(fd, offset, PAGESIZE, POSIX_FADV_DONTNEED);
+		if (pid < 0) {
+			perror("fork");
+			return -1;
+		}
+
+		if (pid)
+			continue;
 
 		/*
-		 * Measure the time to read a PAGESIZE buffer
+		 * Make temporary file, we don't want to pollute the file system
+		 * with big files if this program crashes
 		 */
-		gettimeofday(&begin, NULL);
-		pread(fd, buffer, PAGESIZE, offset);
-		gettimeofday(&end, NULL);
-		latency = ((end.tv_sec - begin.tv_sec) * 1000000) + (
-			end.tv_usec - begin.tv_usec);
+		fd = mktempfile(dirname);
+		if (fd < 0) {
+			perror("mktempfile");
+			return -1;
+		}
+
+		write_file(fd);
 
 		/*
-		 * Fill a bucket with this latency
+		 * Initialize the random seed with the number of
+		 * current usec.  This random value will be used to
+		 * access the file randomly, no sequential accesses
+		 * which can be optimized by the hardware
 		 */
-		bucket_fill(latency);
+		gettimeofday(&begin, NULL);
+		srandom(begin.tv_usec);
+
+		for (i = 0; i < 10000; i++) {
+
+			/*
+			 * Compute the offset address to read from
+			 */
+			offset = (random() % NROFFSET) * PAGESIZE;
+			
+			/*
+			 * man posix_fadvise
+			 */
+			posix_fadvise(fd, offset, PAGESIZE, 
+				      POSIX_FADV_DONTNEED);
+			
+			/*
+			 * Measure the time to read a PAGESIZE buffer
+			 */
+			gettimeofday(&begin, NULL);
+			pread(fd, buffer, PAGESIZE, offset);
+			gettimeofday(&end, NULL);
+			latency = ((end.tv_sec - begin.tv_sec) * 1000000) + (
+				end.tv_usec - begin.tv_usec);
+
+			/*
+			 * Fill a bucket with this latency
+			 */
+			bucket_fill(latency);
+		}
+
+		bucket_show();
+
+		close(fd);
+
+		return 0;
 	}
 
-	bucket_show();
-
-	close(fd);
+	while (wait(NULL) == 0);
 
 	return 0;
 }