schulung_tools: rename/modify malloc to avoid system()

A more complex but cleaner implementation of retrieving/printing
the stats has been implemented. The implementation is put into
a separate stats.c file so that the main program (malloc.) can
be easily reviewed to see what the program is doing.

Signed-off-by: John Ogness <john.ogness@linutronix.de>

5 files changed, 77 insertions, 33 deletions

diff --git a/schulung_tools/malloc/Makefile b/schulung_tools/malloc/Makefile
index b6160a8..a1bd685 100644
--- a/schulung_tools/malloc/Makefile
+++ b/schulung_tools/malloc/Makefile
@@ -1,7 +1,7 @@
-malloc: malloc.c
-	$(CROSS_COMPILE)gcc -g -omalloc malloc.c
+malloc: malloc.c stats.c
+	$(CROSS_COMPILE)gcc -g $^ -o$@
 
 clean:
 	rm -f malloc core
 
-.PHONY: clean
+.PHONY: all clean
diff --git a/schulung_tools/malloc/README b/schulung_tools/malloc/README
deleted file mode 100644
index 77b18cd..0000000
--- a/schulung_tools/malloc/README
+++ /dev/null
@@ -1,5 +0,0 @@
-This program demonstrates that a processes is not actually assigned memory
-until it page-faults on the pages.
-
-WARNING: This program might fill your RAM and cause the Linux OOM Killer to
-         be invoked.
diff --git a/schulung_tools/malloc/README.txt b/schulung_tools/malloc/README.txt
new file mode 100644
index 0000000..d496b5e
--- /dev/null
+++ b/schulung_tools/malloc/README.txt
@@ -0,0 +1,5 @@
+This program demonstrates that a process is not actually assigned memory
+until it page-faults on the pages.
+
+WARNING: This program might fill your RAM and cause the Linux OOM Killer
+         to be invoked.
diff --git a/schulung_tools/malloc/malloc.c b/schulung_tools/malloc/malloc.c
index a636426..76defbe 100644
--- a/schulung_tools/malloc/malloc.c
+++ b/schulung_tools/malloc/malloc.c
@@ -1,57 +1,45 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
 
-#define NUM_OF_GBYTES 8
-
-/* if verbose is enabled forks are done for printing additional informations */
-#define VERBOSE 0
-
-#if VERBOSE
-/* forking is not always possible if memory is low */
-#define sys(cmd) if(system(cmd) == -1) printf("%s failed\n", cmd);
-#else
-#define sys(cmd) ;
-#endif
+extern void print_stats(int);
 
-#define MEMFREE "free -h"
+#define NUM_OF_GBYTES 8
 
 int main(void)
 {
 	char *p[NUM_OF_GBYTES];
 	int i;
 
-	printf("memory usage:\n");
-	sys(MEMFREE);
-	printf("\n\n");
-
 	for (i = 0; i < NUM_OF_GBYTES; i++) {
+		printf("allocating 1GB\n");
+		print_stats(0);
 		p[i] = malloc(1024 * 1024 * 1024);
-		printf("allocated 1GB: %p\n", p[i]);
-		sys(MEMFREE);
+		print_stats(1);
+		printf("    malloc returned: %p\n", p[i]);
 	}
 
-	printf("\n\n");
+	printf("\n");
 
 	for (i = 0; i < NUM_OF_GBYTES; i++) {
 		if (p[i]) {
 			printf("memsetting 1GB: %p\n", p[i]);
-			sys("date +%s.%N");
+			print_stats(0);
 			memset(p[i], 1, 1024 * 1024 * 1024);
-			sys("date +%s.%N");
-			sys(MEMFREE);
+			print_stats(1);
 		}
 	}
 
-	printf("\n\n");
+	printf("\n");
 
 	for (i = 0; i < NUM_OF_GBYTES; i++) {
 		if (p[i]) {
 			printf("free 1GB: %p\n", p[i]);
+			print_stats(0);
 			free(p[i]);
-			sys(MEMFREE);
+			print_stats(1);
 		}
 	}
+
 	return 0;
 }
diff --git a/schulung_tools/malloc/stats.c b/schulung_tools/malloc/stats.c
new file mode 100644
index 0000000..4b17323
--- /dev/null
+++ b/schulung_tools/malloc/stats.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+void print_stats(int postcall)
+{
+	static struct timespec tp1;
+	static struct timespec tp2;
+	static int fd = -1;
+	char buf[32];
+	int virt;
+	int res;
+
+	if (fd == -1)
+		fd = open("/proc/self/statm", O_RDONLY);
+
+	if (!postcall) {
+		clock_gettime(CLOCK_MONOTONIC, &tp1);
+		return;
+	}
+
+	printf("    time=");
+	if (tp1.tv_sec && clock_gettime(CLOCK_MONOTONIC, &tp2) == 0) {
+		if (tp1.tv_nsec > tp2.tv_nsec) {
+			tp2.tv_sec--;
+			tp2.tv_nsec += 1000000000;
+		}
+		tp2.tv_sec -= tp1.tv_sec;
+		tp2.tv_nsec -= tp1.tv_nsec;
+		printf("%d.%06ds ", tp2.tv_sec, tp2.tv_nsec / 1000);
+	} else {
+		tp2.tv_sec = 0;
+		printf("? ");
+	}
+	tp1 = tp2;
+
+	if (fd < 0)
+		goto out;
+
+	lseek(fd, 0, SEEK_SET);
+	if (read(fd, buf, sizeof(buf)) <= 0)
+		goto out;
+
+	if (sscanf(buf, "%d %d ", &virt, &res) != 2)
+		goto out;
+
+	printf("virt=%dKB res=%dKB", virt * 4, res * 4);
+out:
+	printf("\n");
+	fflush(stdout);
+}