use MAP_POPULATE on Linux if -ql

Author: dimkr

vmtouch.c

@@ -504,6 +504,7 @@ void vmtouch_file(char *path) {
   int i;
   int res;
   int open_flags;
+  int mmap_flags = MAP_SHARED;
 
   retry_open:
 
@@ -572,7 +573,13 @@ void vmtouch_file(char *path) {
     len_of_range = len_of_file - offset;
   }
 
-  mem = mmap(NULL, len_of_range, PROT_READ, MAP_SHARED, fd, offset);
+#ifdef __linux__
+  if (o_lock && o_quiet) {
+    mmap_flags |= MAP_POPULATE;
+  }
+#endif
+
+  mem = mmap(NULL, len_of_range, PROT_READ, mmap_flags, fd, offset);
 
   if (mem == MAP_FAILED) {
     warning("unable to mmap file %s (%s), skipping", path, strerror(errno));
@@ -597,7 +604,11 @@ void vmtouch_file(char *path) {
 #else
     fatal("cache eviction not (yet?) supported on this platform");
 #endif
+#ifdef __linux__
+  } else if (!(o_lock && o_quiet)) {
+#else
   } else {
+#endif
     double last_chart_print_time=0.0, temp_time;
     char *mincore_array = malloc(pages_in_range);
     if (mincore_array == NULL) fatal("Failed to allocate memory for mincore array (%s)", strerror(errno));