@@ -18,6 +18,10 @@
#endif
#endif
+#ifndef MAP_NORESERVE
+#define MAP_NORESERVE 0
+#endif
+
#ifdef USE_DEV_ZERO
static int dev_zero = -1;
#endif
@@ -134,7 +138,11 @@
return v;
}
- p = runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, fd, 0);
+ // Use the MAP_NORESERVE mmap() flag here because typically most of
+ // this reservation will never be used. It does not make sense
+ // reserve a huge amount of unneeded swap space. This is important on
+ // systems which do not overcommit memory by default.
+ p = runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_NORESERVE, fd, 0);
if(p == MAP_FAILED)
return nil;
return p;