HLE: Add OS-specific precise sleep methods to reduce spinwaiting (#5948)

* feat: add nanosleep for linux and macos

* Add Windows 0.5ms sleep

- Imprecise waits for longer waits with clock alignment
- 1/4 the spin time on vsync timer

* Remove old experiment

* Fix event leak

* Tweaking for MacOS

* Linux tweaks, nanosleep vsync improvement

* Fix overbias

* Cleanup

* Fix realignment

* Add some docs and some cleanup

NanosleepPool needs more, Nanosleep has some benchmark code that needs removed.

* Rename "Microsleep" to "PreciseSleep"

Might have been confused with "microseconds", which no measurement is performed in.

* Remove nanosleep measurement

* Remove unused debug logging

* Nanosleep Pool Documentation

* More cleanup

* Whitespace

* Formatting

* Address Feedback

* Allow SleepUntilTimePoint to take EventWaitHandle

* Remove `_chrono` stopwatch in SurfaceFlinger

* Move spinwaiting logic to PreciseSleepHelper

Technically, these achieve different things, but having them here makes them easier to reuse or tune.

1 files changed, 84 insertions, 0 deletions

diff --git a/src/Ryujinx.Common/PreciseSleep/NanosleepEvent.cs b/src/Ryujinx.Common/PreciseSleep/NanosleepEvent.cs
new file mode 100644
index 00000000..f54fb09c
--- /dev/null
+++ b/src/Ryujinx.Common/PreciseSleep/NanosleepEvent.cs
@@ -0,0 +1,84 @@
+using System;
+using System.Runtime.Versioning;
+using System.Threading;
+
+namespace Ryujinx.Common.PreciseSleep
+{
+    /// <summary>
+    /// A precise sleep event for linux and macos that uses nanosleep for more precise timeouts.
+    /// </summary>
+    [SupportedOSPlatform("macos")]
+    [SupportedOSPlatform("linux")]
+    [SupportedOSPlatform("android")]
+    [SupportedOSPlatform("ios")]
+    internal class NanosleepEvent : IPreciseSleepEvent
+    {
+        private readonly AutoResetEvent _waitEvent = new(false);
+        private readonly NanosleepPool _pool;
+
+        public NanosleepEvent()
+        {
+            _pool = new NanosleepPool(_waitEvent);
+        }
+
+        public long AdjustTimePoint(long timePoint, long timeoutNs)
+        {
+            // No adjustment
+            return timePoint;
+        }
+
+        public bool SleepUntil(long timePoint)
+        {
+            long now = PerformanceCounter.ElapsedTicks;
+            long delta = (timePoint - now);
+            long ms = Math.Min(delta / PerformanceCounter.TicksPerMillisecond, int.MaxValue);
+            long ns = (delta * 1_000_000) / PerformanceCounter.TicksPerMillisecond;
+
+            if (ms > 0)
+            {
+                _waitEvent.WaitOne((int)ms);
+
+                return true;
+            }
+            else if (ns - Nanosleep.Bias > 0)
+            {
+                // Don't bother starting a sleep if there's already a signal active.
+                if (_waitEvent.WaitOne(0))
+                {
+                    return true;
+                }
+
+                // The 1ms wait will be interrupted by the nanosleep timeout if it completes.
+                if (!_pool.SleepAndSignal(ns, timePoint))
+                {
+                    // Too many threads on the pool.
+                    return false;
+                }
+                _waitEvent.WaitOne(1);
+                _pool.IgnoreSignal();
+
+                return true;
+            }
+
+            return false;
+        }
+
+        public void Sleep()
+        {
+            _waitEvent.WaitOne();
+        }
+
+        public void Signal()
+        {
+            _waitEvent.Set();
+        }
+
+        public void Dispose()
+        {
+            GC.SuppressFinalize(this);
+
+            _pool.Dispose();
+            _waitEvent.Dispose();
+        }
+    }
+}