rsx: FIFO wake-up pause control

rpcs3/Emu/RSX/RSXThread.cpp

@@ -2273,6 +2273,61 @@ namespace rsx
 		}
 	}
 
+	void thread::fifo_wake_delay(u64 div)
+	{
+		// TODO: Nanoseconds accuracy
+		u64 remaining = g_cfg.video.driver_wakeup_delay;
+
+		if (!remaining)
+		{
+			return;
+		}
+
+		// Some cases do not need full delay
+		remaining = ::aligned_div(remaining, div);
+		const u64 until = get_system_time() + remaining;
+
+		while (true)
+		{
+#ifdef __linux__
+			// NOTE: Assumption that timer initialization has succeeded
+			u64 host_min_quantum = remaining <= 1000 ? 10 : 50;
+#else
+			// Host scheduler quantum for windows (worst case)
+			// NOTE: On ps3 this function has very high accuracy
+			constexpr u64 host_min_quantum = 500;
+#endif
+			if (remaining >= host_min_quantum)
+			{
+#ifdef __linux__
+				// Do not wait for the last quantum to avoid loss of accuracy
+				thread_ctrl::wait_for(remaining - ((remaining % host_min_quantum) + host_min_quantum), false);
+#else
+				// Wait on multiple of min quantum for large durations to avoid overloading low thread cpus
+				thread_ctrl::wait_for(remaining - (remaining % host_min_quantum), false);
+#endif
+			}
+			// TODO: Determine best value for yield delay
+			else if (remaining >= host_min_quantum / 2)
+			{
+				std::this_thread::yield();
+			}
+			else
+			{
+				busy_wait(100);
+			}
+
+			const u64 current = get_system_time();
+
+			if (current >= until)
+			{
+				break;
+			}
+
+			remaining = until - current;
+		}
+	}
+
 	u32 thread::get_fifo_cmd()
 	{
 		// Last fifo cmd for logging and utility