Revert "Refactor how ponyint_cpu_core_pause is called (#3989)"

This reverts commit c63b8a7.

This actually did change runtime behavior slightly. Ooops. Bad me
for not seeing that originally. The change has brought some racy
behavior with Windows to the fore so I'm going to revert this.

src/libponyrt/sched/cpu.c

@@ -317,7 +317,7 @@ void ponyint_cpu_affinity(uint32_t cpu)
 /**
  * Only nanosleep if sufficient cycles have elapsed.
  */
-void ponyint_cpu_core_pause(uint64_t tsc, uint64_t tsc2)
+void ponyint_cpu_core_pause(uint64_t tsc, uint64_t tsc2, bool yield)
 {
   uint64_t diff = ponyint_cpu_tick_diff(tsc, tsc2);
 
@@ -331,39 +331,42 @@ void ponyint_cpu_core_pause(uint64_t tsc, uint64_t tsc2)
   struct timespec ts = {0, 0};
 #endif
 
-  // A billion cycles is roughly half a second, depending on clock speed.
-  if(diff > 10000000000)
+  if(yield)
   {
-    // If it has been 10 billion cycles, pause 30 ms.
+    // A billion cycles is roughly half a second, depending on clock speed.
+    if(diff > 10000000000)
+    {
+      // If it has been 10 billion cycles, pause 30 ms.
 #ifdef PLATFORM_IS_WINDOWS
-    ts = 30;
+      ts = 30;
 #else
-    ts.tv_nsec = 30000000;
+      ts.tv_nsec = 30000000;
 #endif
-  } else if(diff > 3000000000) {
-    // If it has been 3 billion cycles, pause 10 ms.
+    } else if(diff > 3000000000) {
+      // If it has been 3 billion cycles, pause 10 ms.
 #ifdef PLATFORM_IS_WINDOWS
-    ts = 10;
+      ts = 10;
 #else
-    ts.tv_nsec = 10000000;
+      ts.tv_nsec = 10000000;
 #endif
-  } else if(diff > 1000000000) {
-    // If it has been 1 billion cycles, pause 1 ms.
+    } else if(diff > 1000000000) {
+      // If it has been 1 billion cycles, pause 1 ms.
 #ifdef PLATFORM_IS_WINDOWS
-    ts = 1;
+      ts = 1;
 #else
-    ts.tv_nsec = 1000000;
+      ts.tv_nsec = 1000000;
 #endif
-  }
-  else
-  {
+    }
+    else
+    {
 #ifdef PLATFORM_IS_WINDOWS
-    // Otherwise, pause for 1 ms (minimum on windows)
-    ts = 1;
+      // Otherwise, pause for 1 ms (minimum on windows)
+      ts = 1;
 #else
-    // Otherwise, pause for 100 microseconds
-    ts.tv_nsec = 100000;
+      // Otherwise, pause for 100 microseconds
+      ts.tv_nsec = 100000;
 #endif
+    }
   }
 
 #ifdef PLATFORM_IS_WINDOWS

src/libponyrt/sched/cpu.h

@@ -17,7 +17,7 @@ uint32_t ponyint_cpu_assign(uint32_t count, scheduler_t* scheduler,
 
 void ponyint_cpu_affinity(uint32_t cpu);
 
-void ponyint_cpu_core_pause(uint64_t tsc, uint64_t tsc2);
+void ponyint_cpu_core_pause(uint64_t tsc, uint64_t tsc2, bool yield);
 
 void ponyint_cpu_relax();
 

src/libponyrt/sched/scheduler.c

@@ -429,9 +429,7 @@ static bool quiescent(scheduler_t* sched, uint64_t tsc, uint64_t tsc2)
     }
   }
 
-  if (use_yield)
-    ponyint_cpu_core_pause(tsc, tsc2);
-
+  ponyint_cpu_core_pause(tsc, tsc2, use_yield);
   return false;
 }