Add malloc-memusage sample

2018/threadoverhead/Makefile

@@ -13,6 +13,7 @@ LDFLAGS = -lpthread
 
 EXECUTABLES = \
 	threadspammer \
+	malloc-memusage \
 	thread-pipe-msgpersec \
 	thread-switch-condvar \
 	thread-switch-pipe
@@ -22,6 +23,9 @@ all: $(EXECUTABLES)
 threadspammer: threadspammer.c
 	$(CC) $(CCFLAGS) $^ -o $@ $(LDFLAGS)
 
+malloc-memusage: malloc-memusage.c
+	$(CC) $(CCFLAGS) $^ -o $@ $(LDFLAGS)
+
 thread-switch-condvar: thread-switch-condvar.c
 	$(CC) $(CCFLAGS) $^ -o $@ $(LDFLAGS)
 

2018/threadoverhead/malloc-memusage.c

@@ -0,0 +1,59 @@
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <unistd.h>
+
+// TODO: parse and report vsz here too
+
+void report_memory(const char* prefix) {
+  struct rusage ru;
+  if (getrusage(RUSAGE_SELF, &ru)) {
+    perror("getrusage");
+		exit(1);
+  }
+
+	char statusfilename[256];
+	snprintf(statusfilename, 256, "/proc/%d/status", getpid());
+
+	FILE* f = fopen(statusfilename, "r");
+	if (!f) {
+		perror("fopen");
+		exit(1);
+	}
+
+	char vmsizebuf[256];
+	char buf[256];
+	while (fgets(buf, 256, f)) {
+		if (strstr(buf, "VmSize") == buf) {
+			strncpy(vmsizebuf, buf + 7, 255);
+			char* pos = strchr(vmsizebuf, '\n');
+			if (pos) {
+				*pos = '\0';
+			}
+			break;
+		}
+	}
+
+	printf("%s: max RSS = %ld; vm size = %s\n", prefix, ru.ru_maxrss, vmsizebuf);
+}
+
+
+int main(int argc, char** argv) {
+  printf("PID = %d\n", getpid());
+	report_memory("started");
+
+	int N = 100 * 1024 * 1024;
+	char* m = malloc(N);
+	report_memory("after malloc");
+
+	/*for (int i = 0; i < N; ++i) {*/
+		/*m[i] = i;*/
+	/*}*/
+	/*report_memory("after touch");*/
+
+  printf("press ENTER\n");
+  (void)fgetc(stdin);
+	return (int)m;
+}

2018/threadoverhead/threadspammer.c

@@ -23,7 +23,6 @@
 
 void* threadfunc(void* p) {
   // Sleep for 10 seconds total.
-	(void)malloc(50000);
   for (int i = 0; i < 10 * 20; ++i) {
     usleep(50 * 1000);
   }