Prioritize the interrupt worker thread.

kernel/include/sortix/kernel/interrupt.h

@@ -29,6 +29,8 @@ namespace Sortix {
 
 struct interrupt_context;
 
+class Thread;
+
 struct interrupt_handler
 {
 	void (*handler)(struct interrupt_context*, void*);
@@ -122,6 +124,9 @@ void Init();
 void WorkerThread(void* user);
 void ScheduleWork(struct interrupt_work* work);
 
+extern Thread* interrupt_worker_thread;
+extern bool interrupt_worker_thread_boost;
+
 } // namespace Interrupt
 } // namespace Sortix
 

kernel/include/sortix/kernel/scheduler.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2012, 2013, 2014 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2011, 2012, 2013, 2014, 2017 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -49,6 +49,7 @@ static inline void ExitThread()
 #endif
 
 void Switch(struct interrupt_context* intctx);
+void SwitchTo(struct interrupt_context* intctx, Thread* new_thread);
 void SetThreadState(Thread* thread, ThreadState state);
 ThreadState GetThreadState(Thread* thread);
 void SetIdleThread(Thread* thread);

kernel/interrupt.cpp

@@ -28,6 +28,9 @@
 namespace Sortix {
 namespace Interrupt {
 
+Thread* interrupt_worker_thread = NULL;
+bool interrupt_worker_thread_boost = false;
+
 static struct interrupt_work* first;
 static struct interrupt_work* last;
 
@@ -63,6 +66,7 @@ void ScheduleWork(struct interrupt_work* work)
 	(last ? last->next : first) = work;
 	work->next = NULL;
 	last = work;
+	interrupt_worker_thread_boost = true;
 }
 
 } // namespace Interrupt

kernel/kernel.cpp

@@ -423,16 +423,17 @@ static void BootThread(void* /*user*/)
 
 	// Let's create the interrupt worker thread that executes additional work
 	// requested by interrupt handlers, where such work isn't safe.
-	Thread* interruptworker = RunKernelThread(Interrupt::WorkerThread, NULL);
-	if ( !interruptworker )
+	Interrupt::interrupt_worker_thread =
+		RunKernelThread(Interrupt::WorkerThread, NULL);
+	if ( !Interrupt::interrupt_worker_thread )
 		Panic("Could not create interrupt worker");
 
 	// Initialize the worker thread data structures.
 	Worker::Init();
 
 	// Create a general purpose worker thread.
-	Thread* workerthread = RunKernelThread(Worker::Thread, NULL);
-	if ( !workerthread )
+	Thread* worker_thread = RunKernelThread(Worker::Thread, NULL);
+	if ( !worker_thread )
 		Panic("Unable to create general purpose worker thread");
 
 	//

kernel/scheduler.cpp

@@ -248,8 +248,9 @@ static void FakeInterruptedContext(struct interrupt_context* intctx, int int_no)
 #endif
 }
 
-static
-void SwitchThread(struct interrupt_context* intctx, Thread* prev, Thread* next)
+static void SwitchRegisters(struct interrupt_context* intctx,
+                            Thread* prev,
+                            Thread* next)
 {
 	if ( prev == next )
 		return;
@@ -264,6 +265,31 @@ void SwitchThread(struct interrupt_context* intctx, Thread* prev, Thread* next)
 	current_thread = next;
 }
 
+static void SwitchThread(struct interrupt_context* intctx,
+                         Thread* old_thread,
+                         Thread* new_thread)
+{
+	SwitchRegisters(intctx, old_thread, new_thread);
+	if ( intctx->signal_pending && InUserspace(intctx) )
+	{
+		// Become the thread for real and run the signal handler.
+		if ( old_thread == new_thread )
+		{
+			// We're already this thread, so run the signal handler.
+			Interrupt::Enable();
+			assert(Interrupt::IsEnabled());
+			Signal::DispatchHandler(intctx, NULL);
+		}
+		else
+		{
+			// We need to transfer execution to the correct stack. We know the
+			// the thread is in user-space and isn't using its kernel stack, and
+			// we know we're not using the stack right now.
+			FakeInterruptedContext(intctx, 130);
+		}
+	}
+}
+
 static Thread* idle_thread;
 static Thread* first_runnable_thread;
 static Thread* true_current_thread;
@@ -308,29 +334,21 @@ static Thread* PopNextThread(bool yielded)
 	return result;
 }
 
+void SwitchTo(struct interrupt_context* intctx, Thread* new_thread)
+{
+	Thread* old_thread = CurrentThread();
+	if ( new_thread == old_thread )
+		return;
+	first_runnable_thread = old_thread;
+	true_current_thread = new_thread;
+	SwitchThread(intctx, old_thread, new_thread);
+}
+
 static void RealSwitch(struct interrupt_context* intctx, bool yielded)
 {
 	Thread* old_thread = CurrentThread();
 	Thread* new_thread = PopNextThread(yielded);
 	SwitchThread(intctx, old_thread, new_thread);
-	if ( intctx->signal_pending && InUserspace(intctx) )
-	{
-		// Become the thread for real and run the signal handler.
-		if ( old_thread == new_thread )
-		{
-			// We're already this thread, so run the signal handler.
-			Interrupt::Enable();
-			assert(Interrupt::IsEnabled());
-			Signal::DispatchHandler(intctx, NULL);
-		}
-		else
-		{
-			// We need to transfer execution to the correct stack. We know the
-			// the thread is in user-space and isn't using its kernel stack, and
-			// we know we're not using the stack right now.
-			FakeInterruptedContext(intctx, 130);
-		}
-	}
 }
 
 void Switch(struct interrupt_context* intctx)

kernel/x86-family/interrupt.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2012, 2013, 2014 Jonas 'Sortie' Termansen.
+ * Copyright (c) 2011, 2012, 2013, 2014, 2017 Jonas 'Sortie' Termansen.
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -357,6 +357,12 @@ extern "C" void interrupt_handler(struct interrupt_context* intctx)
 	// Send an end of interrupt signal to the PICs if we got an IRQ.
 	if ( IRQ0 <= int_no && int_no <= IRQ15 )
 		PIC::SendEOI(int_no - IRQ0);
+
+	if ( interrupt_worker_thread_boost )
+	{
+		interrupt_worker_thread_boost = false;
+		Scheduler::SwitchTo(intctx, interrupt_worker_thread);
+	}
 }
 
 } // namespace Interrupt