Speedup sbrk tst a bit (forking 100Mbyte processes is slow)

11b7438b · Frans Kaashoek · 64797663 · 11b7438b
--- a/usertests.c
+++ b/usertests.c
@@ -1238,7 +1238,7 @@ forktest(void)
 void
 sbrktest(void)
 {
-  int fds[2], pid, pids[32], ppid;
+  int fds[2], pid, pids[10], ppid;
  char *a, *b, *c, *lastaddr, *oldbrk, *p, scratch;
  uint amt;

@@ -1310,6 +1310,13 @@ sbrktest(void)
    exit();
  }

+  a = sbrk(0);
+  c = sbrk(-(sbrk(0) - oldbrk));
+  if(c != a){
+    printf(stdout, "sbrk downsize failed, a %x c %x\n", a, c);
+    exit();
+  }
+  
  // can we read the kernel's memory?
  for(a = (char*)(KERNBASE); a < (char*) (KERNBASE+2000000); a += 50000){
    ppid = getpid();
@@ -1328,15 +1335,14 @@ sbrktest(void)

  // if we run the system out of memory, does it clean up the last
  // failed allocation?
-  sbrk(-(sbrk(0) - oldbrk));
  if(pipe(fds) != 0){
    printf(1, "pipe() failed\n");
    exit();
  }
  for(i = 0; i < sizeof(pids)/sizeof(pids[0]); i++){
    if((pids[i] = fork()) == 0){
-      // allocate the full 640K
-      sbrk((640 * 1024) - (uint)sbrk(0));
+      // allocate a lot of memory
+      sbrk(BIG - (uint)sbrk(0));
      write(fds[1], "x", 1);
      // sit around until killed
      for(;;) sleep(1000);