Sdl backend (#670)

* [audio] added sdl audio backend and in-tree atrac9 decoder

* [input] replaced per-platform pad readers with sdl gamepad input

* [video] added sdl window and host display plumbing

* [gui] added host display options and per-game render settings

* [bink] synced host movie playback to the guest audio clock

* [cpu] hooked windows write faults into guest image tracking

* [perf] added guest and render profiling, reserved host cpu lanes

* [kernel] fixed stale pthread mutex handle alias

* [host] wired the sdl session, save-data paths and project references

* [audio] hoisted ajm trace stackalloc out of its loop

* [video] Add guest image sync setting

* [build] Strip native symbols

* reuse

src/SharpEmu.Libs/Agc/AgcExports.cs

@@ -4383,6 +4383,14 @@ public static partial class AgcExports
                 _tracedProducerlessWaits.Clear();
             }
 
+            if (!stale)
+            {
+                // Count before the deduplication below: the warning fires once
+                // per label, so on its own it cannot say how often a queue
+                // actually suspends.
+                GpuWaitProfile.RecordSuspend(producer is not null);
+            }
+
             if (!stale && producer is null &&
                 !_tracedProducerlessWaits.Add(
                     (memory, waiter.WaitAddress)))
@@ -5648,6 +5656,8 @@ public static partial class AgcExports
 
                 SharpEmu.Libs.Diagnostics.LoadProgressDiagnostics.TraceGpuWaitSnapshot(
                     ctx.Memory);
+                GpuWaitProfile.RecordMonitorPoll(resumed != 0);
+                GpuWaitProfile.ReportIfDue(remaining);
                 if (remaining == 0)
                 {
                     gpuState.WaitMonitorRunning = false;
@@ -5841,6 +5851,7 @@ public static partial class AgcExports
             $"submission={waiter.SubmissionId} label=0x{waiter.WaitAddress:X16} " +
             $"resume=0x{waiter.ResumeAddress:X16} remaining_dwords={remainingDwords} " +
             $"waited_ms={waitedMilliseconds:F3}");
+        GpuWaitProfile.RecordResume(waiter.WaitAddress, waitedMilliseconds);
         if (remainingDwords == 0)
         {
             state.IsSuspended = false;

src/SharpEmu.Libs/Agc/GpuWaitProfile.cs

@@ -0,0 +1,160 @@
+// Copyright (C) 2026 SharpEmu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+using System.Diagnostics;
+
+namespace SharpEmu.Libs.Agc;
+
+/// <summary>
+/// Aggregate accounting for suspended WAIT_REG_MEM packets, enabled with
+/// SHARPEMU_PROFILE_GPU_WAIT=1.
+///
+/// The existing <c>agc.wait_suspended</c> warning is deduplicated per label, so
+/// a label that suspends every frame is reported once and then goes silent —
+/// which makes the log useless for judging whether GPU waits cost frame time.
+/// This counts every suspension and every resume, and reports how long the
+/// queues actually sat blocked.
+/// </summary>
+internal static class GpuWaitProfile
+{
+    public static readonly bool Enabled = string.Equals(
+        Environment.GetEnvironmentVariable("SHARPEMU_PROFILE_GPU_WAIT"),
+        "1",
+        StringComparison.Ordinal);
+
+    private static readonly double _reportSeconds =
+        double.TryParse(
+            Environment.GetEnvironmentVariable("SHARPEMU_PROFILE_GPU_WAIT_REPORT_S"),
+            System.Globalization.CultureInfo.InvariantCulture,
+            out var seconds) && seconds > 0
+            ? seconds
+            : 5.0;
+
+    private static readonly object _gate = new();
+    private static readonly Dictionary<ulong, (long Count, double Milliseconds)> _byLabel = new();
+    private static long _suspensions;
+    private static long _resumes;
+    private static long _producerless;
+    private static long _monitorPolls;
+    private static long _monitorEmptyPolls;
+    private static double _totalWaitMilliseconds;
+    private static double _maxWaitMilliseconds;
+    private static long _windowStart = Stopwatch.GetTimestamp();
+
+    public static void RecordSuspend(bool hasProducer)
+    {
+        if (!Enabled)
+        {
+            return;
+        }
+
+        lock (_gate)
+        {
+            _suspensions++;
+            if (!hasProducer)
+            {
+                _producerless++;
+            }
+        }
+    }
+
+    public static void RecordResume(ulong label, double waitedMilliseconds)
+    {
+        if (!Enabled)
+        {
+            return;
+        }
+
+        lock (_gate)
+        {
+            _resumes++;
+            _totalWaitMilliseconds += waitedMilliseconds;
+            if (waitedMilliseconds > _maxWaitMilliseconds)
+            {
+                _maxWaitMilliseconds = waitedMilliseconds;
+            }
+
+            if (_byLabel.Count < 4096)
+            {
+                var existing = _byLabel.TryGetValue(label, out var entry) ? entry : default;
+                _byLabel[label] = (existing.Count + 1, existing.Milliseconds + waitedMilliseconds);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Called once per wake of the wait monitor. An empty poll means the monitor
+    /// burned a wakeup without resuming anything, which is the cost of the
+    /// backoff loop rather than of the wait itself.
+    /// </summary>
+    public static void RecordMonitorPoll(bool resumedAny)
+    {
+        if (!Enabled)
+        {
+            return;
+        }
+
+        lock (_gate)
+        {
+            _monitorPolls++;
+            if (!resumedAny)
+            {
+                _monitorEmptyPolls++;
+            }
+        }
+    }
+
+    public static void ReportIfDue(int remainingWaiters)
+    {
+        if (!Enabled)
+        {
+            return;
+        }
+
+        string line;
+        lock (_gate)
+        {
+            var now = Stopwatch.GetTimestamp();
+            var elapsedTicks = now - _windowStart;
+            if (elapsedTicks < _reportSeconds * Stopwatch.Frequency)
+            {
+                return;
+            }
+
+            _windowStart = now;
+            var seconds = elapsedTicks / (double)Stopwatch.Frequency;
+
+            // Total blocked time across all queues. Above 1000ms/s the queues are
+            // overlapping their stalls, so compare it against the frame budget,
+            // not against wall time.
+            var top = _byLabel
+                .OrderByDescending(entry => entry.Value.Milliseconds)
+                .Take(5)
+                .Select(entry =>
+                    $"0x{entry.Key:X}={entry.Value.Milliseconds / seconds:F0}ms/s" +
+                    $"/n{entry.Value.Count}")
+                .ToArray();
+
+            line =
+                $"[PERF][GPUWAIT] {seconds:F1}s suspend/s={_suspensions / seconds:F0} " +
+                $"resume/s={_resumes / seconds:F0} producerless/s={_producerless / seconds:F0} " +
+                $"blocked_ms/s={_totalWaitMilliseconds / seconds:F0} " +
+                $"avg_ms={(_resumes > 0 ? _totalWaitMilliseconds / _resumes : 0):F2} " +
+                $"max_ms={_maxWaitMilliseconds:F1} " +
+                $"monitor_polls/s={_monitorPolls / seconds:F0} " +
+                $"empty={(_monitorPolls > 0 ? _monitorEmptyPolls * 100.0 / _monitorPolls : 0):F0}% " +
+                $"outstanding={remainingWaiters} top: {string.Join(" | ", top)}";
+
+            _suspensions = 0;
+            _resumes = 0;
+            _producerless = 0;
+            _monitorPolls = 0;
+            _monitorEmptyPolls = 0;
+            _totalWaitMilliseconds = 0;
+            _maxWaitMilliseconds = 0;
+            _byLabel.Clear();
+        }
+
+        Console.Error.WriteLine(line);
+    }
+}