Relax test expectations in BootUpMemoryUse.

test/cctest/test-mark-compact.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 455 matching lines @@
 static uintptr_t ReadLong(char* buffer, intptr_t* position, int base) {
   char* end_address = buffer + *position;
   uintptr_t result = strtoul(buffer + *position, &end_address, base);
   CHECK(result != ULONG_MAX || errno != ERANGE);
   CHECK(end_address > buffer + *position);
   *position = end_address - buffer;
   return result;
 }
 
 
+// The memory use computed this way is not entirely accurate and depends on
+// the way malloc allocates memory.  That's why the memory usage may seem to
+// increase even though the sum of the allocated memory sizes decreases.  It
+// also means that the memory use depends on the kernel and stdlib.
 static intptr_t MemoryInUse() {
   intptr_t memory_use = 0;
 
   int fd = open("/proc/self/maps", O_RDONLY);
   if (fd < 0) return -1;
 
   const int kBufSize = 10000;
   char buffer[kBufSize];
   int length = read(fd, buffer, kBufSize);
   intptr_t line_start = 0;
@@ skipping 45 matching lines @@
   intptr_t initial_memory = MemoryInUse();
   // Avoid flakiness.
   FLAG_crankshaft = false;
   FLAG_parallel_recompilation = false;
 
   // Only Linux has the proc filesystem and only if it is mapped.  If it's not
   // there we just skip the test.
   if (initial_memory >= 0) {
     InitializeVM();
     intptr_t delta = MemoryInUse() - initial_memory;
-    if (sizeof(initial_memory) == 8) {
+    printf("delta: %" V8_PTR_PREFIX "d kB\n", delta / 1024);
+    if (sizeof(initial_memory) == 8) {  // 64-bit.
       if (v8::internal::Snapshot::IsEnabled()) {
-        CHECK_LE(delta, 3600 * 1024);  // 3396.
+        CHECK_LE(delta, 3700 * 1024);
       } else {
-        CHECK_LE(delta, 4000 * 1024);  // 3948.
+        CHECK_LE(delta, 4200 * 1024);
       }
-    } else {
+    } else {                            // 32-bit.
       if (v8::internal::Snapshot::IsEnabled()) {
-        CHECK_LE(delta, 2600 * 1024);  // 2400.
+        CHECK_LE(delta, 2600 * 1024);
       } else {
-        CHECK_LE(delta, 3000 * 1024);  // 2920.
+        CHECK_LE(delta, 3000 * 1024);
       }
     }
   }
 }
 
 #endif  // __linux__ and !USE_SIMULATOR