Removed Tensor Overrides Native Memory Allocations

LLama/Extensions/IModelParamsExtensions.cs

@@ -3,6 +3,7 @@
 using System.Text;
 using LLama.Abstractions;
 using LLama.Native;
+using System.Collections.Generic;
 
 namespace LLama.Extensions;
 
@@ -45,20 +46,13 @@ public static IDisposable ToLlamaModelParams(this IModelParams @params, out LLam
             result.tensor_split = (float*)disposer.Add(@params.TensorSplits.Pin()).Pointer;
         }
 
-        // Add tensor buffer overrides, if any
-        if (@params.TensorBufferOverrides.Count > 0)
+        // Add tensor buffer overrides
+        unsafe
         {
-            var bufferOverrideHelper = new LLamaTensorBufferOverrideHelper();
-            disposer.Add(bufferOverrideHelper);
-
-            foreach (var tensorOverride in @params.TensorBufferOverrides)
-            {
-                bufferOverrideHelper.AddOverride(tensorOverride.Pattern, tensorOverride.BufferType);
-            }
-
-            bufferOverrideHelper.ApplyToModelParams(ref result);
+            result.tensor_buft_overrides = ConvertOverrides(@params.TensorBufferOverrides, disposer);
         }
 
+        // Add metadata overrides
         if (@params.MetadataOverrides.Count == 0)
         {
             unsafe
@@ -106,4 +100,69 @@ public static IDisposable ToLlamaModelParams(this IModelParams @params, out LLam
 
         return disposer;
     }
+
+    /// <summary>
+    /// Get a map from name of device (`ggml_backend_buft_name`) to the device type (`ggml_backend_dev_buffer_type`)
+    /// </summary>
+    /// <returns>Dictionary mapping buffer type names to their handles</returns>
+    private static IReadOnlyDictionary<string, IntPtr> GetAvailableBufferTypes()
+    {
+        var result = new Dictionary<string, IntPtr>();
+
+        var count = NativeApi.ggml_backend_dev_count();
+        for (nuint i = 0; i < count; i++)
+        {
+            var dev = NativeApi.ggml_backend_dev_get(i);
+            var buft = NativeApi.ggml_backend_dev_buffer_type(dev);
+
+            var name = Marshal.PtrToStringAnsi(NativeApi.ggml_backend_buft_name(buft));
+            if (string.IsNullOrEmpty(name))
+                continue;
+
+            result[name] = buft;
+        }
+
+        return result;
+    }
+
+    private static unsafe LLamaModelTensorBufferOverride* ConvertOverrides(List<TensorBufferOverride> overrides, GroupDisposable disposer)
+    {
+        // Early out if there are no overrides
+        if (overrides.Count == 0)
+            return null;
+
+        var bufferTypes = GetAvailableBufferTypes();
+
+        var overridesCount = 0;
+        var overridesArray = new LLamaModelTensorBufferOverride[overrides.Count + 1];
+
+        foreach (var @override in overrides)
+        {
+            // Check if we have this buffer type
+            if (!bufferTypes.TryGetValue(@override.BufferType, out var bufferType))
+                continue;
+
+            // Create null terminated string and pin this memory so it can be passed to native code
+            var patternBytes = Encoding.UTF8.GetBytes(@override.Pattern + "\0");
+            var patternPin = patternBytes.AsMemory().Pin();
+            disposer.Add(patternPin);
+
+            // Add the item to the overridesArray
+            overridesArray[overridesCount++] = new()
+            {
+                Pattern = (byte*)patternPin.Pointer,
+                BufferType = bufferType
+            };
+        }
+
+        // Early out if there were no valid overrides
+        if (overridesCount == 0)
+            return null;
+
+        // Pin it so it can be safely passed across to native code
+        var overrideArrayPin = overridesArray.AsMemory().Pin();
+        disposer.Add(overrideArrayPin);
+
+        return (LLamaModelTensorBufferOverride*)overrideArrayPin.Pointer;
+    }
 }

LLama/Native/LLamaModelTensorBufferOverride.cs

@@ -7,12 +7,12 @@ namespace LLama.Native
     /// Original type: llama_model_tensor_buft_override
     /// </summary>
     [StructLayout(LayoutKind.Sequential)]
-    public struct LLamaModelTensorBufferOverride
+    public unsafe struct LLamaModelTensorBufferOverride
     {
         /// <summary>
         /// Tensor name pattern to match
         /// </summary>
-        public IntPtr Pattern;
+        public byte* Pattern;
 
         /// <summary>
         /// Backend buffer type to use for matching tensors, as obtained via ggml_backend_dev_buffer_type