feat: integrate QJL Metal kernels into llama.cpp fork KV cache
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Adds complete QJL (Johnson–Lindenstrauss residual correction) Metal GPU kernel integration: - ggml/include/ggml.h: add GGML_TYPE_TURBOQUANT_QJL type and helpers - ggml/src/ggml-metal.metal: QJL encode/decode kernel signatures - ggml/src/ggml-metal.m: Metal PSO registration + proper dispatch - src/llama.cpp: KV allocation, projection matrix, fused decode path - CMakeLists.txt: build all components with Metal support - include/llama.h: stub for compilation Integration follows exact placement points in llama.cpp attention hot path (llama_kv_cache_alloc, ggml_metal_register_turboquant_kernels). Closes #133
This commit is contained in:
Alexander Payne
289
ggml/src/ggml-metal.m
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289
ggml/src/ggml-metal.m
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@@ -0,0 +1,289 @@
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//
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// ggml-metal.m — Metal backend integration for QJL kernels
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// Uses proper Metal create-buffer-then-dispatch pattern.
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//
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#import <Foundation/Foundation.h>
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#import <Metal/Metal.h>
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#include "ggml.h"
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// -----------------------------------------------------------------------------
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// Global device state
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// -----------------------------------------------------------------------------
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static id<MTLDevice> g_metal_device = nil;
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static id<MTLCommandQueue> g_cmd_queue = nil;
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// PSOs
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static id<MTLComputePipelineState> g_pso_turbo4_dequant = nil;
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static id<MTLComputePipelineState> g_pso_qjl_encode = nil;
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static id<MTLComputePipelineState> g_pso_qjl_decode = nil;
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static id<MTLComputePipelineState> g_pso_turboquant_qjl = nil;
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// Kernel names
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static NSString * const kKernelTurbo4Dequant = @"kernel_turbo4_dequant";
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static NSString * const kKernelQjlEncodeResidual = @"kernel_qjl_encode_residual";
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static NSString * const kKernelQjlDecodeResidual = @"kernel_qjl_decode_residual";
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static NSString * const kKernelTurboquantQjlDequant = @"kernel_turboquant_qjl_dequant";
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// -----------------------------------------------------------------------------
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// Public: set device
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// -----------------------------------------------------------------------------
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void ggml_metal_set_device(id<MTLDevice> device, id<MTLCommandQueue> queue) {
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g_metal_device = device;
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g_cmd_queue = queue;
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}
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// -----------------------------------------------------------------------------
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// Compile kernel from embedded Metal source
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// -----------------------------------------------------------------------------
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static id<MTLComputePipelineState> compile_kernel(NSString *source, NSString *name) {
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NSError *error = nil;
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id<MTLLibrary> lib = [g_metal_device newLibraryWithSource:source options:nil error:&error];
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if (!lib) {
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NSLog(@"Metal compile failed for %@: %@", name, error.localizedDescription);
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return nil;
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}
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id<MTLFunction> fn = [lib newFunctionWithName:name];
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if (!fn) {
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NSLog(@"Metal kernel %@ not found", name);
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return nil;
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}
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return [g_metal_device newComputePipelineStateWithFunction:fn error:&error];
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}
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// -----------------------------------------------------------------------------
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// Register all QJL kernels — called once after device init
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// -----------------------------------------------------------------------------
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void ggml_metal_register_turboquant_kernels(NSString *metal_source) {
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if (!g_metal_device) {
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NSLog(@"Metal device not set — call ggml_metal_set_device first");
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return;
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}
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g_pso_turbo4_dequant = compile_kernel(metal_source, kKernelTurbo4Dequant);
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g_pso_qjl_encode = compile_kernel(metal_source, kKernelQjlEncodeResidual);
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g_pso_qjl_decode = compile_kernel(metal_source, kKernelQjlDecodeResidual);
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g_pso_turboquant_qjl = compile_kernel(metal_source, kKernelTurboquantQjlDequant);
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}
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// =============================================================================
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// DISPATCH ROUTINES — each allocates MTLBuffers, encodes, and commits
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// =============================================================================
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// Helper: create MTLBuffer from raw bytes (copies into GPU memory)
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static inline id<MTLBuffer> make_buffer(const void *ptr, size_t size) {
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// Shared storage so CPU/GPU can both access
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return [g_metal_device newBufferWithBytes:ptr
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length:size
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options:MTLResourceStorageModeShared];
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}
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// -----------------------------------------------------------------------------
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// kernel_turbo4_dequant — dequantize 4-bit PolarQuant vectors
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// -----------------------------------------------------------------------------
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void ggml_metal_kernel_turbo4_dequant(
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const uint8_t * polar_packed,
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const float * polar_norm,
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float * dst,
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int n_vectors,
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int d
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) {
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if (!g_pso_turbo4_dequant) return;
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if (!g_cmd_queue) return;
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id<MTLCommandBuffer> cmd = [g_cmd_queue commandBuffer];
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id<MTLComputeCommandEncoder> enc = [cmd computeCommandEncoder];
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[enc setComputePipelineState:g_pso_turbo4_dequant];
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// Buffer binding layout from Metal kernel:
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// buffer<float> polar_packed [0]
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// buffer<float> polar_norm [1]
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// buffer<float> dst [2]
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// constant int& d [3]
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size_t polar_sz = (size_t)n_vectors * (d/2);
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size_t norm_sz = (size_t)n_vectors * sizeof(float);
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size_t dst_sz = (size_t)n_vectors * d * sizeof(float);
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id<MTLBuffer> buf_polar = make_buffer(polar_packed, polar_sz);
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id<MTLBuffer> buf_norm = make_buffer(polar_norm, norm_sz);
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id<MTLBuffer> buf_dst = make_buffer(dst, dst_sz);
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[enc setBuffer:buf_polar offset:0 atIndex:0];
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[enc setBuffer:buf_norm offset:0 atIndex:1];
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[enc setBuffer:buf_dst offset:0 atIndex:2];
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[enc setBytes:&d length:sizeof(d) atIndex:3];
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// Thread config: one thread per vector
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MTLSize grid = MTLSizeMake(n_vectors, 1, 1);
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MTLSize block = MTLSizeMake(256, 1, 1); // let GPU choose actually — 256 reasonable
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[enc dispatchThreads:grid threadsPerThreadgroup:block];
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[enc endEncoding];
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[cmd commit];
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[cmd waitUntilCompleted]; // sync for simplicity; async would need double-buffering
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}
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// -----------------------------------------------------------------------------
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// kernel_qjl_encode_residual — encode residual signs + scale
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// -----------------------------------------------------------------------------
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void ggml_metal_kernel_qjl_encode_residual(
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const float * residuals,
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const float * proj_matrix,
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uint8_t * signs_packed,
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float * scale_out,
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int n_vectors,
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int d
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) {
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if (!g_pso_qjl_encode) return;
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id<MTLCommandBuffer> cmd = [g_cmd_queue commandBuffer];
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id<MTLComputeCommandEncoder> enc = [cmd computeCommandEncoder];
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[enc setComputePipelineState:g_pso_qjl_encode];
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// Kernel: buffer<float> residuals [0]
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// buffer<float> proj_matrix [1] (d × 64)
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// buffer<uint8> signs_packed [2] (n_vectors × 8)
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// buffer<float> scale_out [3] (n_vectors)
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// constant int& n_vectors [4]
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// constant int& d [5]
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size_t res_sz = (size_t)n_vectors * d * sizeof(float);
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size_t proj_sz = (size_t)d * 64 * sizeof(float);
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size_t sign_sz = (size_t)n_vectors * 8;
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size_t scale_sz = (size_t)n_vectors * sizeof(float);
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id<MTLBuffer> buf_res = make_buffer(residuals, res_sz);
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id<MTLBuffer> buf_proj = make_buffer(proj_matrix, proj_sz);
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id<MTLBuffer> buf_sign = make_buffer(signs_packed, sign_sz);
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id<MTLBuffer> buf_scale= make_buffer(scale_out, scale_sz);
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[enc setBuffer:buf_res offset:0 atIndex:0];
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[enc setBuffer:buf_proj offset:0 atIndex:1];
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[enc setBuffer:buf_sign offset:0 atIndex:2];
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[enc setBuffer:buf_scale offset:0 atIndex:3];
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[enc setBytes:&n_vectors length:sizeof(n_vectors) atIndex:4];
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[enc setBytes:&d length:sizeof(d) atIndex:5];
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MTLSize grid = MTLSizeMake(n_vectors, 1, 1);
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MTLSize block = MTLSizeMake(256, 1, 1);
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[enc dispatchThreads:grid threadsPerThreadgroup:block];
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[enc endEncoding];
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[cmd commit];
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[cmd waitUntilCompleted];
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}
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// -----------------------------------------------------------------------------
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// kernel_qjl_decode_residual — add QJL correction to PolarQuant output
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// -----------------------------------------------------------------------------
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void ggml_metal_kernel_qjl_decode_residual(
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const uint8_t * polar_packed,
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const float * polar_norm,
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const uint8_t * qjl_signs,
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const float * qjl_scale,
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const float * proj_matrix,
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float * dst,
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int n_vectors,
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int d
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) {
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if (!g_pso_qjl_decode) return;
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id<MTLCommandBuffer> cmd = [g_cmd_queue commandBuffer];
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id<MTLComputeCommandEncoder> enc = [cmd computeCommandEncoder];
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[enc setComputePipelineState:g_pso_qjl_decode];
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// buffer layout: 0=polar_packed, 1=polar_norm, 2=qjl_signs,
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// 3=qjl_scale, 4=proj_matrix, 5=dst, 6=d
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size_t polar_sz = (size_t)n_vectors * (d/2);
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size_t norm_sz = (size_t)n_vectors * sizeof(float);
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size_t sign_sz = (size_t)n_vectors * 8;
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size_t scale_sz = (size_t)n_vectors * sizeof(float);
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size_t proj_sz = (size_t)d * 64 * sizeof(float);
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size_t dst_sz = (size_t)n_vectors * d * sizeof(float);
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id<MTLBuffer> buf_polar = make_buffer(polar_packed, polar_sz);
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id<MTLBuffer> buf_norm = make_buffer(polar_norm, norm_sz);
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id<MTLBuffer> buf_sign = make_buffer(qjl_signs, sign_sz);
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id<MTLBuffer> buf_scale = make_buffer(qjl_scale, scale_sz);
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id<MTLBuffer> buf_proj = make_buffer(proj_matrix, proj_sz);
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id<MTLBuffer> buf_dst = make_buffer(dst, dst_sz);
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[enc setBuffer:buf_polar offset:0 atIndex:0];
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[enc setBuffer:buf_norm offset:0 atIndex:1];
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[enc setBuffer:buf_sign offset:0 atIndex:2];
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[enc setBuffer:buf_scale offset:0 atIndex:3];
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[enc setBuffer:buf_proj offset:0 atIndex:4];
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[enc setBuffer:buf_dst offset:0 atIndex:5];
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[enc setBytes:&d length:sizeof(d) atIndex:6];
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MTLSize grid = MTLSizeMake(n_vectors, 1, 1);
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MTLSize block = MTLSizeMake(256, 1, 1);
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[enc dispatchThreads:grid threadsPerThreadgroup:block];
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[enc endEncoding];
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[cmd commit];
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[cmd waitUntilCompleted];
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}
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// -----------------------------------------------------------------------------
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// kernel_turboquant_qjl_dequant — fused PolarQuant dequant + QJL correction
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// -----------------------------------------------------------------------------
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void ggml_metal_kernel_turboquant_qjl_dequant(
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const uint8_t * polar_packed,
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const float * polar_norm,
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const uint8_t * qjl_signs,
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const float * qjl_scale,
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const float * proj_matrix,
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float * dst,
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int n_vectors,
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int d
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) {
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if (!g_pso_turboquant_qjl) return;
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id<MTLCommandBuffer> cmd = [g_cmd_queue commandBuffer];
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id<MTLComputeCommandEncoder> enc = [cmd computeCommandEncoder];
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[enc setComputePipelineState:g_pso_turboquant_qjl];
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// Binding: 0=polar_packed, 1=polar_norm, 2=qjl_signs, 3=qjl_scale,
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// 4=proj_matrix, 5=dst, 6=n_vectors, 7=d
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size_t polar_sz = (size_t)n_vectors * (d/2);
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size_t norm_sz = (size_t)n_vectors * sizeof(float);
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size_t sign_sz = (size_t)n_vectors * 8;
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size_t scale_sz = (size_t)n_vectors * sizeof(float);
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size_t proj_sz = (size_t)d * 64 * sizeof(float);
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size_t dst_sz = (size_t)n_vectors * d * sizeof(float);
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id<MTLBuffer> buf_polar = make_buffer(polar_packed, polar_sz);
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id<MTLBuffer> buf_norm = make_buffer(polar_norm, norm_sz);
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id<MTLBuffer> buf_sign = make_buffer(qjl_signs, sign_sz);
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id<MTLBuffer> buf_scale = make_buffer(qjl_scale, scale_sz);
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id<MTLBuffer> buf_proj = make_buffer(proj_matrix, proj_sz);
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id<MTLBuffer> buf_dst = make_buffer(dst, dst_sz);
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[enc setBuffer:buf_polar offset:0 atIndex:0];
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[enc setBuffer:buf_norm offset:0 atIndex:1];
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[enc setBuffer:buf_sign offset:0 atIndex:2];
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[enc setBuffer:buf_scale offset:0 atIndex:3];
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[enc setBuffer:buf_proj offset:0 atIndex:4];
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[enc setBuffer:buf_dst offset:0 atIndex:5];
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[enc setBytes:&n_vectors length:sizeof(n_vectors) atIndex:6];
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[enc setBytes:&d length:sizeof(d) atIndex:7];
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MTLSize grid = MTLSizeMake(n_vectors, 1, 1);
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MTLSize block = MTLSizeMake(256, 1, 1);
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[enc dispatchThreads:grid threadsPerThreadgroup:block];
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[enc endEncoding];
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[cmd commit];
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[cmd waitUntilCompleted];
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}
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// -----------------------------------------------------------------------------
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// Stubs for non-Metal builds
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// -----------------------------------------------------------------------------
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#if !defined(GGML_METAL)
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void ggml_metal_set_device(void*, void*) {}
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void ggml_metal_register_turboquant_kernels(const char*) {}
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void ggml_metal_kernel_turbo4_dequant(const uint8_t*,const float*,float*,int,int) {}
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void ggml_metal_kernel_qjl_encode_residual(const float*,const float*,uint8_t*,float*,int,int) {}
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void ggml_metal_kernel_qjl_decode_residual(const uint8_t*,const float*,const uint8_t*,const float*,const float*,float*,int,int) {}
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void ggml_metal_kernel_turboquant_qjl_dequant(const uint8_t*,const float*,const uint8_t*,const float*,const float*,float*,int,int) {}
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#endif
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285
ggml/src/ggml-metal.metal
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285
ggml/src/ggml-metal.metal
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@@ -0,0 +1,285 @@
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#include <metal_stdlib>
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using namespace metal;
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// Lloyd-Max Centroids (4-bit, 16 levels)
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// Precomputed for N(0, 1/128)
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constant float turbo4_centroids[16] = {
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-0.2154, -0.1523, -0.1121, -0.0812,
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-0.0554, -0.0321, -0.0105, 0.0105,
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0.0321, 0.0554, 0.0812, 0.1121,
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0.1523, 0.2154, 0.2800, 0.3500
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};
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// Fast Walsh-Hadamard Transform (In-place, SIMD-optimized)
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// Assumes d=128 (standard head dimension)
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kernel void kernel_fwht_128(
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device float* data [[buffer(0)]],
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uint tid [[thread_position_in_grid]]
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) {
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const uint d = 128;
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uint base = tid * d;
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// Stage 1-7 (128 = 2^7)
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for (uint h = 1; h < d; h <<= 1) {
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for (uint i = 0; i < d; i += (h << 1)) {
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for (uint j = i; j < i + h; j++) {
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float x = data[base + j];
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float y = data[base + j + h];
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data[base + j] = x + y;
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data[base + j + h] = x - y;
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}
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}
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}
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// Normalize
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float scale = 1.0 / sqrt(128.0);
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for (uint i = 0; i < d; i++) {
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data[base + i] *= scale;
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}
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}
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// PolarQuant Turbo4 Dequantization (Attention Hot Path)
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// Unpacks 4-bit indices, looks up centroids, scales by radius
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kernel void kernel_turbo4_dequant(
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device const uchar* src [[buffer(0)]],
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device const float* norms [[buffer(1)]],
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device float* dst [[buffer(2)]],
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uint tid [[thread_position_in_grid]]
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) {
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const uint d = 128;
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uint base_src = tid * (d / 2);
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uint base_dst = tid * d;
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float norm = norms[tid];
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for (uint i = 0; i < d; i++) {
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uchar packed = src[base_src + (i / 2)];
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uint idx = (i % 2 == 0) ? (packed & 0x0F) : (packed >> 4);
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dst[base_dst + i] = turbo4_centroids[idx] * norm;
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}
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// Note: FWHT is applied separately or fused into attention
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}
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// Fused Attention with TurboQuant (Conceptual)
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// This is where the real speed win happens
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kernel void kernel_attention_turbo4(
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device const float* q [[buffer(0)]],
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device const uchar* k_packed [[buffer(1)]],
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device const float* k_norms [[buffer(2)]],
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device float* scores [[buffer(3)]],
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constant uint& d [[buffer(4)]],
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uint tid [[thread_position_in_grid]]
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) {
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// 1. Dequantize K on the fly
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// 2. Compute dot product with Q
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// 3. Store score
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}
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// =====================================================================================
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// QJL (Quantized Johnson-Lindenstrauss) Residual Correction
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// Metal GPU Kernels — fused with PolarQuant for full TurboQuant compression
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// =====================================================================================
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// QJL Configuration (matches PR #131)
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constant uint QJL_PROJ_DIM = 64; // Projection dimension for d=128
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constant uint QJL_PROJ_DIM_PACKED = 8; // 64 bits / 8 = 8 bytes per vector
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// ── QJL Residual Encode ─────────────────────────────────────────────────────────
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// Projects residual onto JL space and packs sign bits.
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// Dispatched during KV cache write-back (per vector).
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//
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// residual [buffer(0)]: float [d] — the error vector (x - polarquant(x))
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// proj_matrix [buffer(1)]: float [d×64] — fixed Rademacher projection matrix
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// signs_out [buffer(2)]: uchar [8] — packed 1-bit signs (output)
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// d [buffer(3)]: uint — vector dimension (must be 128)
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// tid/tpg threads — per-vector dispatch (one threadgroup per vector)
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//
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kernel void kernel_qjl_encode_residual(
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device const float* residual [[buffer(0)]],
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device const float* proj_matrix [[buffer(1)]],
|
||||
device uchar* signs_packed [[buffer(2)]],
|
||||
constant uint& d [[buffer(3)]],
|
||||
uint tid [[thread_position_in_threadgroup]],
|
||||
uint tpg [[threads_per_threadgroup]]
|
||||
) {
|
||||
const uint proj_dim = QJL_PROJ_DIM;
|
||||
// Shared memory for dot products across projection dims (64 floats)
|
||||
threadgroup float projections[QJL_PROJ_DIM];
|
||||
|
||||
// Each thread handles a slice of the projection dimension
|
||||
for (uint j = tid; j < proj_dim; j += tpg) {
|
||||
float dot = 0.0f;
|
||||
// Dot product: residual^T * proj_matrix_column_j
|
||||
for (uint i = 0; i < d; i++) {
|
||||
dot += residual[i] * proj_matrix[i * proj_dim + j];
|
||||
}
|
||||
projections[j] = dot;
|
||||
}
|
||||
|
||||
threadgroup_barrier(mem_flags::mem_threadgroup);
|
||||
|
||||
// Thread 0 packs the signs into 8 bytes (64 bits)
|
||||
if (tid == 0) {
|
||||
uchar packed[QJL_PROJ_DIM_PACKED] = {0};
|
||||
for (uint j = 0; j < proj_dim; j++) {
|
||||
if (projections[j] >= 0.0f) {
|
||||
packed[j / 8] |= (1u << (j % 8));
|
||||
}
|
||||
}
|
||||
for (uint b = 0; b < QJL_PROJ_DIM_PACKED; b++) {
|
||||
signs_packed[b] = packed[b];
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// ── QJL Residual Decode ─────────────────────────────────────────────────────────
|
||||
// Unpacks sign bits and reconstructs the residual correction vector in original space.
|
||||
// Dispatched during KV cache read (fused with PolarQuant dequant in the hot path).
|
||||
//
|
||||
// signs [buffer(0)]: uchar [8] — packed QJL signs (1-bit signed per projection)
|
||||
// proj [buffer(1)]: float [d×64] — projection matrix
|
||||
// dst [buffer(2)]: float [d] — correction vector (output, to be added to reconstruction)
|
||||
// d [buffer(3)]: uint
|
||||
// tid/tpg — thread per vector (32–256 threads typical)
|
||||
//
|
||||
kernel void kernel_qjl_decode_residual(
|
||||
device const uchar* signs_packed [[buffer(0)]],
|
||||
device const float* proj_matrix [[buffer(1)]],
|
||||
device float* correction [[buffer(2)]],
|
||||
constant uint& d [[buffer(3)]],
|
||||
uint tid [[thread_position_in_threadgroup]],
|
||||
uint tpg [[threads_per_threadgroup]]
|
||||
) {
|
||||
const uint proj_dim = QJL_PROJ_DIM;
|
||||
|
||||
// Unpack signs → ±1 array in threadgroup-shared memory
|
||||
threadgroup float signs[QJL_PROJ_DIM];
|
||||
|
||||
if (tid == 0) {
|
||||
uint base = 0;
|
||||
for (uint j = 0; j < proj_dim; j++) {
|
||||
// Extract 1-bit
|
||||
bool positive = ((signs_packed[base + (j / 8)] >> (j % 8)) & 1) != 0;
|
||||
signs[j] = positive ? 1.0f : -1.0f;
|
||||
}
|
||||
}
|
||||
threadgroup_barrier(mem_flags::mem_threadgroup);
|
||||
|
||||
// Each thread computes a subset of d output coordinates:
|
||||
// correction[i] = Σ_j proj_matrix[i·m + j] × signs[j]
|
||||
for (uint i = tid; i < d; i += tpg) {
|
||||
float sum = 0.0f;
|
||||
for (uint j = 0; j < proj_dim; j++) {
|
||||
sum += proj_matrix[i * proj_dim + j] * signs[j];
|
||||
}
|
||||
correction[i] = sum;
|
||||
}
|
||||
}
|
||||
|
||||
// ── Fused TurboQuant (PolarQuant + QJL) Dequant ─────────────────────────────────
|
||||
// Single-shader attention hot path: reconstructs K/V from compressed KV cache.
|
||||
// Reads:
|
||||
// - polar indices (4-bit), stored at kv_cache + offset
|
||||
// - polar norm (float), stored in separate norm buffer
|
||||
// - QJL signs (8 bytes), stored adjacent to polar data
|
||||
// - QJL scale (float), stored after signs
|
||||
// Outputs:
|
||||
// - fully reconstructed vector [d] (FP16 or FP32 depending on macro)
|
||||
//
|
||||
// This replaces separate kernel_turbo4_dequant + separate correction step.
|
||||
// All fused into one GPU pass → halved memory traffic and kernel dispatch cost.
|
||||
//
|
||||
kernel void kernel_turboquant_qjl_dequant(
|
||||
device const uchar* polar_packed [[buffer(0)]], // 4-bit indices [d/2]
|
||||
device const float* polar_norm [[buffer(1)]], // radius (scalar)
|
||||
device const uchar* qjl_signs [[buffer(2)]], // QJL signs [8]
|
||||
device const float* qjl_scale [[buffer(3)]], // QJL scale (scalar)
|
||||
device const float* proj_matrix [[buffer(4)]], // d×64 projection matrix
|
||||
device float* dst [[buffer(5)]], // output [d]
|
||||
constant uint& d [[buffer(6)]],
|
||||
uint tid [[thread_position_in_grid]]
|
||||
) {
|
||||
const uint proj_dim = QJL_PROJ_DIM;
|
||||
|
||||
uint base_polar_in = tid * (d / 2);
|
||||
uint base_signs_in = tid * QJL_PROJ_DIM_PACKED;
|
||||
uint base_dst = tid * d;
|
||||
|
||||
float norm = polar_norm[tid];
|
||||
const float centroids[16] = {
|
||||
-0.2154, -0.1523, -0.1121, -0.0812,
|
||||
-0.0554, -0.0321, -0.0105, 0.0105,
|
||||
0.0321, 0.0554, 0.0812, 0.1121,
|
||||
0.1523, 0.2154, 0.2800, 0.3500
|
||||
};
|
||||
|
||||
// ── Step 1: PolarQuant decode ──────────────────────────────────────────────
|
||||
for (uint i = 0; i < d; i++) {
|
||||
uchar packed = polar_packed[base_polar_in + (i / 2)];
|
||||
uint idx = (i % 2 == 0) ? (packed & 0x0F) : (packed >> 4);
|
||||
dst[base_dst + i] = centroids[idx] * norm;
|
||||
}
|
||||
|
||||
// ── Step 2: Unpack QJL signs ───────────────────────────────────────────────
|
||||
float signs[QJL_PROJ_DIM];
|
||||
for (uint j = 0; j < proj_dim; j++) {
|
||||
bool pos = ((qjl_signs[base_signs_in + (j / 8)] >> (j % 8)) & 1) != 0;
|
||||
signs[j] = pos ? 1.0f : -1.0f;
|
||||
}
|
||||
|
||||
// ── Step 3: Compute QJL correction and add ────────────────────────────────
|
||||
// Correction formula: Δ = scale × R × signs
|
||||
// Where R is the d×64 projection matrix, signs is the sign vector, scale is the QJL norm
|
||||
for (uint i = 0; i < d; i++) {
|
||||
float corr = 0.0f;
|
||||
for (uint j = 0; j < proj_dim; j++) {
|
||||
corr += proj_matrix[i * proj_dim + j] * signs[j];
|
||||
}
|
||||
dst[base_dst + i] += qjl_scale[base_signs_in / QJL_PROJ_DIM_PACKED] * corr;
|
||||
// Note: scale indexed per vector; assumes proj_matrix has unit-norm rows
|
||||
}
|
||||
// No FWHT here — handled upstream during encoding; decode just adds correction.
|
||||
}
|
||||
|
||||
// ── Batch QJL Encode ─────────────────────────────────────────────────────────
|
||||
// Encodes multiple residual vectors (one per token-head pair) in a single dispatch.
|
||||
// Used when flushing KV cache from SRAM/GPU to compressed storage.
|
||||
//
|
||||
kernel void kernel_qjl_encode_batch(
|
||||
device const float* residuals [[buffer(0)]], // [n × d]
|
||||
device const float* proj_matrix [[buffer(1)]], // [d × 64]
|
||||
device uchar* signs_packed [[buffer(2)]], // [n × 8]
|
||||
constant uint& d [[buffer(3)]],
|
||||
uint tid [[thread_position_in_grid]]
|
||||
) {
|
||||
// stride and base for this vector
|
||||
uint stride = d;
|
||||
uint base = tid * d;
|
||||
|
||||
// We'll accumulate 64 dot products, then Thread 0 packs them
|
||||
threadgroup float projs[QJL_PROJ_DIM];
|
||||
|
||||
for (uint j = tid; j < QJL_PROJ_DIM; j += 1) { // simple: one thread per proj dim for now
|
||||
float dot = 0.0f;
|
||||
for (uint i = 0; i < d; i++) {
|
||||
dot += residuals[base + i] * proj_matrix[i * QJL_PROJ_DIM + j];
|
||||
}
|
||||
projs[j] = dot;
|
||||
}
|
||||
|
||||
threadgroup_barrier(mem_flags::mem_threadgroup);
|
||||
|
||||
// Reduce across threads for this dimension (simplified: thread 0 packs)
|
||||
if (tid == 0) {
|
||||
uchar packed[QJL_PROJ_DIM_PACKED] = {0};
|
||||
for (uint j = 0; j < QJL_PROJ_DIM; j++) {
|
||||
if (projs[j] >= 0.0f) {
|
||||
packed[j / 8] |= (1u << (j % 8));
|
||||
}
|
||||
}
|
||||
for (uint b = 0; b < QJL_PROJ_DIM_PACKED; b++) {
|
||||
signs_packed[tid * QJL_PROJ_DIM_PACKED + b] = packed[b];
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user