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Diffstat (limited to 'src/Ryujinx.Graphics.Gpu/Memory/BufferBackingState.cs')
| -rw-r--r-- | src/Ryujinx.Graphics.Gpu/Memory/BufferBackingState.cs | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/src/Ryujinx.Graphics.Gpu/Memory/BufferBackingState.cs b/src/Ryujinx.Graphics.Gpu/Memory/BufferBackingState.cs new file mode 100644 index 00000000..3f65131e --- /dev/null +++ b/src/Ryujinx.Graphics.Gpu/Memory/BufferBackingState.cs @@ -0,0 +1,294 @@ +using Ryujinx.Graphics.GAL; +using System; +using System.Collections.Generic; + +namespace Ryujinx.Graphics.Gpu.Memory +{ + /// <summary> + /// Type of backing memory. + /// In ascending order of priority when merging multiple buffer backing states. + /// </summary> + internal enum BufferBackingType + { + HostMemory, + DeviceMemory, + DeviceMemoryWithFlush + } + + /// <summary> + /// Keeps track of buffer usage to decide what memory heap that buffer memory is placed on. + /// Dedicated GPUs prefer certain types of resources to be device local, + /// and if we need data to be read back, we might prefer that they're in host memory. + /// + /// The measurements recorded here compare to a set of heruristics (thresholds and conditions) + /// that appear to produce good performance in most software. + /// </summary> + internal struct BufferBackingState + { + private const int DeviceLocalSizeThreshold = 256 * 1024; // 256kb + + private const int SetCountThreshold = 100; + private const int WriteCountThreshold = 50; + private const int FlushCountThreshold = 5; + private const int DeviceLocalForceExpiry = 100; + + public readonly bool IsDeviceLocal => _activeType != BufferBackingType.HostMemory; + + private readonly SystemMemoryType _systemMemoryType; + private BufferBackingType _activeType; + private BufferBackingType _desiredType; + + private bool _canSwap; + + private int _setCount; + private int _writeCount; + private int _flushCount; + private int _flushTemp; + private int _lastFlushWrite; + private int _deviceLocalForceCount; + + private readonly int _size; + + /// <summary> + /// Initialize the buffer backing state for a given parent buffer. + /// </summary> + /// <param name="context">GPU context</param> + /// <param name="parent">Parent buffer</param> + /// <param name="stage">Initial buffer stage</param> + /// <param name="baseBuffers">Buffers to inherit state from</param> + public BufferBackingState(GpuContext context, Buffer parent, BufferStage stage, IEnumerable<Buffer> baseBuffers = null) + { + _size = (int)parent.Size; + _systemMemoryType = context.Capabilities.MemoryType; + + // Backend managed is always auto, unified memory is always host. + _desiredType = BufferBackingType.HostMemory; + _canSwap = _systemMemoryType != SystemMemoryType.BackendManaged && _systemMemoryType != SystemMemoryType.UnifiedMemory; + + if (_canSwap) + { + // Might want to start certain buffers as being device local, + // and the usage might also lock those buffers into being device local. + + BufferStage storageFlags = stage & BufferStage.StorageMask; + + if (parent.Size > DeviceLocalSizeThreshold && baseBuffers == null) + { + _desiredType = BufferBackingType.DeviceMemory; + } + + if (storageFlags != 0) + { + // Storage buffer bindings may require special treatment. + + var rawStage = stage & BufferStage.StageMask; + + if (rawStage == BufferStage.Fragment) + { + // Fragment read should start device local. + + _desiredType = BufferBackingType.DeviceMemory; + + if (storageFlags != BufferStage.StorageRead) + { + // Fragment write should stay device local until the use doesn't happen anymore. + + _deviceLocalForceCount = DeviceLocalForceExpiry; + } + } + + // TODO: Might be nice to force atomic access to be device local for any stage. + } + + if (baseBuffers != null) + { + foreach (Buffer buffer in baseBuffers) + { + CombineState(buffer.BackingState); + } + } + } + } + + /// <summary> + /// Combine buffer backing types, selecting the one with highest priority. + /// </summary> + /// <param name="left">First buffer backing type</param> + /// <param name="right">Second buffer backing type</param> + /// <returns>Combined buffer backing type</returns> + private static BufferBackingType CombineTypes(BufferBackingType left, BufferBackingType right) + { + return (BufferBackingType)Math.Max((int)left, (int)right); + } + + /// <summary> + /// Combine the state from the given buffer backing state with this one, + /// so that the state isn't lost when migrating buffers. + /// </summary> + /// <param name="oldState">Buffer state to combine into this state</param> + private void CombineState(BufferBackingState oldState) + { + _setCount += oldState._setCount; + _writeCount += oldState._writeCount; + _flushCount += oldState._flushCount; + _flushTemp += oldState._flushTemp; + _lastFlushWrite = -1; + _deviceLocalForceCount = Math.Max(_deviceLocalForceCount, oldState._deviceLocalForceCount); + + _canSwap &= oldState._canSwap; + + _desiredType = CombineTypes(_desiredType, oldState._desiredType); + } + + /// <summary> + /// Get the buffer access for the desired backing type, and record that type as now being active. + /// </summary> + /// <param name="parent">Parent buffer</param> + /// <returns>Buffer access</returns> + public BufferAccess SwitchAccess(Buffer parent) + { + BufferAccess access = parent.SparseCompatible ? BufferAccess.SparseCompatible : BufferAccess.Default; + + bool isBackendManaged = _systemMemoryType == SystemMemoryType.BackendManaged; + + if (!isBackendManaged) + { + switch (_desiredType) + { + case BufferBackingType.HostMemory: + access |= BufferAccess.HostMemory; + break; + case BufferBackingType.DeviceMemory: + access |= BufferAccess.DeviceMemory; + break; + case BufferBackingType.DeviceMemoryWithFlush: + access |= BufferAccess.DeviceMemoryMapped; + break; + } + } + + _activeType = _desiredType; + + return access; + } + + /// <summary> + /// Record when data has been uploaded to the buffer. + /// </summary> + public void RecordSet() + { + _setCount++; + + ConsiderUseCounts(); + } + + /// <summary> + /// Record when data has been flushed from the buffer. + /// </summary> + public void RecordFlush() + { + if (_lastFlushWrite != _writeCount) + { + // If it's on the same page as the last flush, ignore it. + _lastFlushWrite = _writeCount; + _flushCount++; + } + } + + /// <summary> + /// Determine if the buffer backing should be changed. + /// </summary> + /// <returns>True if the desired backing type is different from the current type</returns> + public readonly bool ShouldChangeBacking() + { + return _desiredType != _activeType; + } + + /// <summary> + /// Determine if the buffer backing should be changed, considering a new use with the given buffer stage. + /// </summary> + /// <param name="stage">Buffer stage for the use</param> + /// <returns>True if the desired backing type is different from the current type</returns> + public bool ShouldChangeBacking(BufferStage stage) + { + if (!_canSwap) + { + return false; + } + + BufferStage storageFlags = stage & BufferStage.StorageMask; + + if (storageFlags != 0) + { + if (storageFlags != BufferStage.StorageRead) + { + // Storage write. + _writeCount++; + + var rawStage = stage & BufferStage.StageMask; + + if (rawStage == BufferStage.Fragment) + { + // Switch to device memory, swap back only if this use disappears. + + _desiredType = CombineTypes(_desiredType, BufferBackingType.DeviceMemory); + _deviceLocalForceCount = DeviceLocalForceExpiry; + + // TODO: Might be nice to force atomic access to be device local for any stage. + } + } + + ConsiderUseCounts(); + } + + return _desiredType != _activeType; + } + + /// <summary> + /// Evaluate the current counts to determine what the buffer's desired backing type is. + /// This method depends on heuristics devised by testing a variety of software. + /// </summary> + private void ConsiderUseCounts() + { + if (_canSwap) + { + if (_writeCount >= WriteCountThreshold || _setCount >= SetCountThreshold || _flushCount >= FlushCountThreshold) + { + if (_deviceLocalForceCount > 0 && --_deviceLocalForceCount != 0) + { + // Some buffer usage demanded that the buffer stay device local. + // The desired type was selected when this counter was set. + } + else if (_flushCount > 0 || _flushTemp-- > 0) + { + // Buffers that flush should ideally be mapped in host address space for easy copies. + // If the buffer is large it will do better on GPU memory, as there will be more writes than data flushes (typically individual pages). + // If it is small, then it's likely most of the buffer will be flushed so we want it on host memory, as access is cached. + _desiredType = _size > DeviceLocalSizeThreshold ? BufferBackingType.DeviceMemoryWithFlush : BufferBackingType.HostMemory; + } + else if (_writeCount >= WriteCountThreshold) + { + // Buffers that are written often should ideally be in the device local heap. (Storage buffers) + _desiredType = BufferBackingType.DeviceMemory; + } + else if (_setCount > SetCountThreshold) + { + // Buffers that have their data set often should ideally be host mapped. (Constant buffers) + _desiredType = BufferBackingType.HostMemory; + } + + // It's harder for a buffer that is flushed to revert to another type of mapping. + if (_flushCount > 0) + { + _flushTemp = 1000; + } + + _lastFlushWrite = -1; + _flushCount = 0; + _writeCount = 0; + _setCount = 0; + } + } + } + } +} |