timeval: On Linux x86-64 systems refresh time whenever it is requested.

[sliver-openvswitch.git] / lib / timeval.h

diff --git a/lib/timeval.h b/lib/timeval.h
index cc50cb3..1384848 100644 (file)
--- a/lib/timeval.h
+++ b/lib/timeval.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,6 +36,21 @@ BUILD_ASSERT_DECL(TYPE_IS_INTEGER(time_t));
  * ever encounter such a platform. */
 BUILD_ASSERT_DECL(TYPE_IS_SIGNED(time_t));
 
+/* On x86-64 systems, Linux avoids using syscalls for clock_gettime().
+ *
+ * For systems which do invoke a system call we wait at least
+ * TIME_UPDATE_INTERVAL ms between clock_gettime() calls and cache the time for
+ * the interim.
+ *
+ * For systems which do not invoke a system call, we just call clock_gettime()
+ * whenever the time is requested.  As a result we don't start the background
+ * SIGALRM timer unless explicitly needed by time_alarm() */
+#if defined __x86_64__ && defined __linux__
+#define CACHE_TIME 0
+#else
+#define CACHE_TIME 1
+#endif
+
 #define TIME_MAX TYPE_MAXIMUM(time_t)
 #define TIME_MIN TYPE_MINIMUM(time_t)
 
@@ -44,7 +59,6 @@ BUILD_ASSERT_DECL(TYPE_IS_SIGNED(time_t));
  * much time will be wasted in signal handlers and calls to clock_gettime(). */
 #define TIME_UPDATE_INTERVAL 100
 
-void time_init(void);
 void time_disable_restart(void);
 void time_enable_restart(void);
 void time_postfork(void);
@@ -56,11 +70,18 @@ long long int time_wall_msec(void);
 void time_timespec(struct timespec *);
 void time_wall_timespec(struct timespec *);
 void time_alarm(unsigned int secs);
-int time_poll(struct pollfd *, int n_pollfds, int timeout);
+int time_poll(struct pollfd *, int n_pollfds, long long int timeout_when,
+              int *elapsed);
 
 long long int timespec_to_msec(const struct timespec *);
 long long int timeval_to_msec(const struct timeval *);
 
+void xgettimeofday(struct timeval *);
+
+int get_cpu_usage(void);
+
+long long int time_boot_msec(void);
+
 #ifdef  __cplusplus
 }
 #endif