Revert "Use clock_gettime() to time steps"

This reverts commit 4654968d.

Teach me to do more than one thing at a time...

src/engine.c

@@ -28,7 +28,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <time.h>
 #include <unistd.h>
 #include <stdbool.h>
 
@@ -1465,29 +1464,6 @@ void engine_init_particles(struct engine *e) {
   e->step = -1;
 }
 
-
-/**
- * brief Get difference in milli-seconds between two timespecs.
- *
- * @param start the start time.
- * @param end the end time.
- *
- * @return the difference in milli-secinds.
- */
-static double time_diff(struct timespec start, struct timespec end)
-{
-  struct timespec temp;
-  if ((end.tv_nsec-start.tv_nsec)<0) {
-    temp.tv_sec = end.tv_sec-start.tv_sec-1;
-    temp.tv_nsec = 1000000000+end.tv_nsec-start.tv_nsec;
-  } else {
-    temp.tv_sec = end.tv_sec-start.tv_sec;
-    temp.tv_nsec = end.tv_nsec-start.tv_nsec;
-  }
-  return (double)temp.tv_sec*1000.0 + (double)temp.tv_nsec*1.0E-6;
-}
-
-
 /**
  * @brief Let the #engine loose to compute the forces.
  *
@@ -1506,9 +1482,6 @@ void engine_step(struct engine *e) {
 
   TIMER_TIC2;
 
-  struct timespec time1, time2;
-  clock_gettime(CLOCK_REALTIME, &time1);
-
   /* Collect the cell data. */
   for (k = 0; k < s->nr_cells; k++)
     if (s->cells[k].nodeID == e->nodeID) {
@@ -1580,8 +1553,8 @@ void engine_step(struct engine *e) {
   if (e->nodeID == 0) {
 
     /* Print some information to the screen */
-    printf("%d %e %e %d %.3f %.3f\n", e->step, e->time, e->timeStep, updates,
-           e->wallclock_time, e->wallclock_time_ticks);
+    printf("%d %e %e %d %.3f\n", e->step, e->time, e->timeStep, updates,
+           e->wallclock_time);
     fflush(stdout);
 
     /* Write some energy statistics */
@@ -1647,11 +1620,7 @@ void engine_step(struct engine *e) {
 
   TIMER_TOC2(timer_step);
 
-  clock_gettime(CLOCK_REALTIME, &time2);
-
-  e->wallclock_time_ticks = ((double)timers[timer_count - 1]) / CPU_TPS * 1000;
-
-  e->wallclock_time = (float) time_diff(time1, time2);
+  e->wallclock_time = ((double)timers[timer_count - 1]) / CPU_TPS * 1000;
   // printParticle(e->s->parts, e->s->xparts,1000, e->s->nr_parts);
   // printParticle(e->s->parts, e->s->xparts,515050, e->s->nr_parts);
 }

src/engine.h

@@ -147,7 +147,6 @@ struct engine {
 
   /* Wallclock time of the last time-step */
   float wallclock_time;
-  float wallclock_time_ticks;
 
   /* Force the engine to rebuild? */
   int forcerebuild;