OS-5192 need faster clock_gettime
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Joshua M. Clulow <jmc@joyent.com>
Reviewed by: Ryan Zezeski <ryan@zinascii.com>

@@ -20,11 +20,11 @@
  */
 
 /*
  * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2014 Garrett D'Amore <garrett@damore.org>
- * Copyright 2015 Joyent, Inc.
+ * Copyright 2016 Joyent, Inc.
  */
 
 /*
  * Implementation of all external interfaces between ld.so.1 and libc.
  *

@@ -719,11 +719,26 @@
 isalnum(int c)
 {
         return ((isalpha(c) || isdigit(c)) ? 1 : 0);
 }
 
+#if defined(__i386) || defined(__amd64)
 /*
+ * Instead of utilizing the comm page for clock_gettime, rtld uses the raw
+ * syscall instead.  Doing so decreases the surface of symbols needed from libc
+ * for a modest performance cost.
+ */
+extern int __clock_gettime_sys(clockid_t, struct timespec *);
+
+int
+__clock_gettime(clockid_t clock_id, struct timespec *tp)
+{
+        return (__clock_gettime_sys(clock_id, tp));
+}
+#endif /* defined(__i386) || defined(__amd64) */
+
+/*
  * In a similar vein to the is* functions above, we also have to define our own
  * version of strerror, as it is implemented in terms of the locale aware
  * strerror_l, and we'd rather not have the full set of libc symbols used here.
  */
 extern const char _sys_errs[];