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likely/unlikely branch prediction
[lttv.git]
/
ltt
/
branches
/
poly
/
ltt
/
time.h
diff --git
a/ltt/branches/poly/ltt/time.h
b/ltt/branches/poly/ltt/time.h
index a257018275262b2dd2da7b87a5fc1e1598492a02..fe7641dfbbf49fdcc871e37ac3d55e1994a36b40 100644
(file)
--- a/
ltt/branches/poly/ltt/time.h
+++ b/
ltt/branches/poly/ltt/time.h
@@
-20,7
+20,7
@@
#define LTT_TIME_H
#include <glib.h>
#define LTT_TIME_H
#include <glib.h>
-
+#include <ltt/compiler.h>
typedef struct _LttTime {
unsigned long tv_sec;
typedef struct _LttTime {
unsigned long tv_sec;
@@
-42,7
+42,11
@@
static inline LttTime ltt_time_sub(LttTime t1, LttTime t2)
LttTime res;
res.tv_sec = t1.tv_sec - t2.tv_sec;
res.tv_nsec = t1.tv_nsec - t2.tv_nsec;
LttTime res;
res.tv_sec = t1.tv_sec - t2.tv_sec;
res.tv_nsec = t1.tv_nsec - t2.tv_nsec;
- if(t1.tv_nsec < t2.tv_nsec) {
+ /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
+ * higher probability of low value for t2.tv_sec, we will habitually
+ * not wrap.
+ */
+ if(unlikely(t1.tv_nsec < t2.tv_nsec)) {
res.tv_sec--;
res.tv_nsec += NANOSECONDS_PER_SECOND;
}
res.tv_sec--;
res.tv_nsec += NANOSECONDS_PER_SECOND;
}
@@
-55,16
+59,17
@@
static inline LttTime ltt_time_add(LttTime t1, LttTime t2)
LttTime res;
res.tv_nsec = t1.tv_nsec + t2.tv_nsec;
res.tv_sec = t1.tv_sec + t2.tv_sec;
LttTime res;
res.tv_nsec = t1.tv_nsec + t2.tv_nsec;
res.tv_sec = t1.tv_sec + t2.tv_sec;
- if(res.tv_nsec >= NANOSECONDS_PER_SECOND) {
+ /* unlikely : given equal chance to be anywhere in t1.tv_nsec, and
+ * higher probability of low value for t2.tv_sec, we will habitually
+ * not wrap.
+ */
+ if(unlikely(res.tv_nsec >= NANOSECONDS_PER_SECOND)) {
res.tv_sec++;
res.tv_nsec -= NANOSECONDS_PER_SECOND;
}
return res;
}
res.tv_sec++;
res.tv_nsec -= NANOSECONDS_PER_SECOND;
}
return res;
}
-#define likely(x) __builtin_expect(!!(x), 1)
-#define unlikely(x) __builtin_expect(!!(x), 0)
-
/* Fastest comparison : t1 > t2 */
static inline int ltt_time_compare(LttTime t1, LttTime t2)
{
/* Fastest comparison : t1 > t2 */
static inline int ltt_time_compare(LttTime t1, LttTime t2)
{
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