+#ifdef HAVE_POSIX_FADVISE
+ /* don't pollute the buffer cache with data read from the file. We do this while reading to
+ keep damage minimal */
+ if (0 != posix_fadvise(fileno(in_file), rrd_head_size, 0, POSIX_FADV_DONTNEED)) {
+ rrd_set_error("setting POSIX_FADV_DONTNEED on '%s': %s",filename, rrd_strerror(errno));
+ fclose(in_file);
+ return(-1);
+ }
+#endif
+