Merge pull request #2408 from Subv/priority_boosting

Kernel: Removed the priority boost code for starved threads.

src/core/hle/kernel/thread.cpp

@@ -141,28 +141,6 @@ void ArbitrateAllThreads(u32 address) {
     }
 }
 
-/// Boost low priority threads (temporarily) that have been starved
-static void PriorityBoostStarvedThreads() {
-    u64 current_ticks = CoreTiming::GetTicks();
-
-    for (auto& thread : thread_list) {
-        // TODO(bunnei): Threads that have been waiting to be scheduled for `boost_ticks` (or
-        // longer) will have their priority temporarily adjusted to 1 higher than the highest
-        // priority thread to prevent thread starvation. This general behavior has been verified
-        // on hardware. However, this is almost certainly not perfect, and the real CTR OS scheduler
-        // should probably be reversed to verify this.
-
-        const u64 boost_timeout = 2000000; // Boost threads that have been ready for > this long
-
-        u64 delta = current_ticks - thread->last_running_ticks;
-
-        if (thread->status == THREADSTATUS_READY && delta > boost_timeout) {
-            const s32 priority = std::max(ready_queue.get_first()->current_priority - 1, 0);
-            thread->BoostPriority(priority);
-        }
-    }
-}
-
 /**
  * Switches the CPU's active thread context to that of the specified thread
  * @param new_thread The thread to switch to
@@ -196,9 +174,6 @@ static void SwitchContext(Thread* new_thread) {
         ready_queue.remove(new_thread->current_priority, new_thread);
         new_thread->status = THREADSTATUS_RUNNING;
 
-        // Restores thread to its nominal priority if it has been temporarily changed
-        new_thread->current_priority = new_thread->nominal_priority;
-
         Core::CPU().LoadContext(new_thread->context);
         Core::CPU().SetCP15Register(CP15_THREAD_URO, new_thread->GetTLSAddress());
     } else {
@@ -534,8 +509,6 @@ SharedPtr<Thread> SetupMainThread(u32 entry_point, s32 priority) {
 }
 
 void Reschedule() {
-    PriorityBoostStarvedThreads();
-
     Thread* cur = GetCurrentThread();
     Thread* next = PopNextReadyThread();