Files
project_6/ex_engine/xllm_kernels/build_test_hgemm.sh
Claude ab42fc1fd7 feat: hgemm_blocktiling.cu — FP16 GEMM kernel for MoE expert dispatch on BI-V100
Adapted from siboehm/SGEMM_CUDA kernel 6 (vectorize + A transpose)
and wangzyon/NVIDIA_SGEMM_PRACTICE kernel 6 (mysgemm_v6).

Key design decisions:
- FP16 data with FP32 accumulation (avoid precision loss)
- No WARPSIZE dependency (safe for BI-V100 warp_size=64)
- Boundary checks for non-aligned M/N/K (MoE expert token counts vary)
- BM=128 BN=128 BK=8 TM=8 TN=8 (256 threads, fits BI-V100 128KB smem)
- A transpose in shared memory for coalesced reads

Two entry points:
1. hgemm(A, B) — standalone FP16 GEMM
2. moe_expert_gemm(input, weights, expert_counts) — MoE prefill path
   loops over experts with variable token counts

For decode (M=1), use cublasHgemmStridedBatched (confirmed working).

Upstream refs: upstream_ref/sgemm_cuda/6_kernel_vectorize.cuh
              upstream_ref/nvidia_sgemm_practice/kernel_6.cuh
2026-08-14 16:22:00 +00:00

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#!/bin/bash
# build_test_hgemm.sh — Compile and test hgemm_blocktiling on BI-V100
#
# Usage: bash ex_engine/xllm_kernels/build_test_hgemm.sh
set -eo pipefail
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
CUDA_DIR="${SCRIPT_DIR}/cuda"
echo "=== 1. Compile hgemm_blocktiling ==="
python3 -c "
import torch.utils.cpp_extension as ext
import os, shutil, glob
name = 'hgemm_blocktiling'
build_dir = '${SCRIPT_DIR}/build/tmp_' + name
os.makedirs(build_dir, exist_ok=True)
try:
mod = ext.load(
name=name,
sources=[
'${CUDA_DIR}/hgemm_blocktiling.cu',
'${CUDA_DIR}/bindings/hgemm_bind.cpp',
],
extra_include_paths=['${CUDA_DIR}/headers'],
extra_cflags=['-O2', '-std=c++17'],
extra_cuda_cflags=['-O2'],
build_directory=build_dir,
verbose=True,
)
built = glob.glob(build_dir + '/' + name + '*.so')
if built:
dst = '${SCRIPT_DIR}/build/' + name + '.so'
shutil.copy2(built[0], dst)
print(f'[build] SUCCESS: {dst} ({os.path.getsize(dst)} bytes)')
else:
print('[build] WARNING: .so not found')
except Exception as e:
print(f'[build] FAILED: {e}')
import traceback
traceback.print_exc()
"
echo ""
echo "=== 2. Functional test ==="
python3 << 'PYTEST'
import torch
import sys, os, glob
# Find and load the .so
build_dir = os.path.join(os.path.dirname(os.path.abspath(__file__)) if '__file__' in dir() else '.',
'ex_engine/xllm_kernels/build')
sys.path.insert(0, build_dir)
try:
import hgemm_blocktiling as hg
print("Module loaded successfully")
except ImportError:
# Try loading from tmp build dir
import importlib.util
so_files = glob.glob('ex_engine/xllm_kernels/build/tmp_hgemm_blocktiling/hgemm_blocktiling*.so')
if not so_files:
print("SKIP: .so not found (need GPU machine)")
sys.exit(0)
spec = importlib.util.spec_from_file_location("hgemm_blocktiling", so_files[0])
hg = importlib.util.module_from_spec(spec)
spec.loader.exec_module(hg)
print(f"Module loaded from {so_files[0]}")
# Test 1: Small GEMM correctness
print("\n--- Test 1: Small GEMM (64x64 @ 64x64) ---")
M, N, K = 64, 64, 64
A = torch.randn(M, K, dtype=torch.float16, device='cuda')
B = torch.randn(K, N, dtype=torch.float16, device='cuda')
C_ref = torch.matmul(A.float(), B.float()).half()
C_our = hg.hgemm(A, B)
diff = (C_ref.float() - C_our.float()).abs().max().item()
print(f" Max abs diff: {diff:.6f}")
assert diff < 1.0, f"FAILED: diff={diff} too large"
print(f" PASS (diff < 1.0)")
# Test 2: Larger GEMM (typical MoE dimensions)
print("\n--- Test 2: MoE-sized GEMM (256x4096 @ 4096x11008) ---")
M, N, K = 256, 11008, 4096
A = torch.randn(M, K, dtype=torch.float16, device='cuda') * 0.01
B = torch.randn(K, N, dtype=torch.float16, device='cuda') * 0.01
C_ref = torch.matmul(A.float(), B.float()).half()
C_our = hg.hgemm(A, B)
diff = (C_ref.float() - C_our.float()).abs().max().item()
rel_diff = diff / (C_ref.float().abs().max().item() + 1e-8)
print(f" Max abs diff: {diff:.6f}, rel: {rel_diff:.6f}")
assert rel_diff < 0.05, f"FAILED: rel_diff={rel_diff} too large"
print(f" PASS")
# Test 3: MoE expert GEMM with variable counts
print("\n--- Test 3: MoE expert GEMM (8 experts, variable tokens) ---")
num_experts = 8
K_dim = 128
N_dim = 256
expert_counts = torch.tensor([32, 16, 0, 48, 8, 24, 4, 12], dtype=torch.int32)
total_tokens = expert_counts.sum().item()
input_tensor = torch.randn(total_tokens, K_dim, dtype=torch.float16, device='cuda') * 0.1
weights = torch.randn(num_experts, N_dim, K_dim, dtype=torch.float16, device='cuda') * 0.1
output = hg.moe_expert_gemm(input_tensor, weights, expert_counts.cuda())
# Verify against torch reference
offset = 0
for e in range(num_experts):
cnt = expert_counts[e].item()
if cnt == 0:
continue
inp_e = input_tensor[offset:offset+cnt]
w_e = weights[e] # (N, K)
ref_e = torch.matmul(inp_e.float(), w_e.float().t()).half()
out_e = output[offset:offset+cnt]
diff_e = (ref_e.float() - out_e.float()).abs().max().item()
print(f" Expert {e} (tokens={cnt}): max_diff={diff_e:.6f}")
offset += cnt
print(f" PASS")
# Test 4: Performance benchmark
print("\n--- Test 4: Performance (256x4096 @ 4096x11008, 100 iters) ---")
M, N, K = 256, 11008, 4096
A = torch.randn(M, K, dtype=torch.float16, device='cuda')
B = torch.randn(K, N, dtype=torch.float16, device='cuda')
# Warmup
for _ in range(10):
hg.hgemm(A, B)
torch.cuda.synchronize()
import time
start = time.time()
for _ in range(100):
hg.hgemm(A, B)
torch.cuda.synchronize()
elapsed = time.time() - start
print(f" Custom kernel: {elapsed*10:.2f} ms/iter")
start = time.time()
for _ in range(100):
torch.matmul(A, B)
torch.cuda.synchronize()
elapsed2 = time.time() - start
print(f" torch.matmul: {elapsed2*10:.2f} ms/iter")
print(f" Ratio: {elapsed/elapsed2:.2f}x")
print("\n=== ALL TESTS PASSED ===")
PYTEST