Files
project_6/qwen3_6_scripts/test_cccl_preload.sh
Claude 327c2c9044 feat(CCCL): LD_PRELOAD CachingDeviceAllocator — intercept cudaMalloc/cudaFree
Route C: replace PyTorch's cudaMalloc/cudaFree with CCCL CUB's
CachingDeviceAllocator via LD_PRELOAD. Eliminates driver-level allocation
overhead by reusing freed GPU memory from a bin-based cache.

Based on cccl_upstream/cub/cub/util_allocator.cuh (901 lines).
Self-contained .so with no CCCL header dependencies at compile time.

Files:
- cccl_preload_allocator.cu: the allocator (405 lines)
- build_cccl_preload_allocator.sh: build script (corex clang++ or g++ fallback)
- test_cccl_preload.sh: smoke test suite for BI-V100
- patch_ops.sh: build during docker build
- computility-run.yaml: LD_PRELOAD env var for runtime

Config via env:
  CCCL_ALLOC_BIN_GROWTH=8, MIN_BIN=3, MAX_BIN=13, MAX_CACHED_MB=4096

Test on real machine:
  cd qwen3_6_scripts && bash test_cccl_preload.sh
2026-08-13 09:21:52 +00:00

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#!/usr/bin/env bash
# Quick test for CCCL preload allocator on BI-V100
# Usage: cd /home/dylan/project_6/qwen3_6_scripts && bash test_cccl_preload.sh
set -eo pipefail
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
SO="${SCRIPT_DIR}/cccl_preload_allocator.so"
echo "=== Step 1: Build ==="
bash "${SCRIPT_DIR}/build_cccl_preload_allocator.sh" "${SCRIPT_DIR}"
echo ""
if [[ ! -f "$SO" ]]; then
echo "BUILD FAILED: $SO not found"
exit 1
fi
echo "=== Step 2: Basic smoke test (torch.zeros on GPU) ==="
echo "Without preload:"
python3 -c "
import time, torch
t0=time.time()
for i in range(100):
x=torch.zeros(1024*1024, device='cuda')
del x
torch.cuda.synchronize()
print(f'100 alloc+free cycles: {time.time()-t0:.3f}s')
"
echo ""
echo "With CCCL preload:"
CCCL_ALLOC_DEBUG=0 LD_PRELOAD="$SO" python3 -c "
import time, torch
t0=time.time()
for i in range(100):
x=torch.zeros(1024*1024, device='cuda')
del x
torch.cuda.synchronize()
print(f'100 alloc+free cycles: {time.time()-t0:.3f}s')
" 2>&1
echo ""
echo "=== Step 3: Varied sizes (simulating model inference allocations) ==="
CCCL_ALLOC_DEBUG=0 LD_PRELOAD="$SO" python3 -c "
import time, torch
# Simulate inference: repeated allocs of same sizes (should hit cache)
sizes = [512, 4096, 32768, 262144, 1048576, 4194304, 16777216] # 512B to 16MB
tensors = []
print('First pass (cold cache):')
t0 = time.time()
for s in sizes:
x = torch.empty(s // 2, dtype=torch.float16, device='cuda') # s bytes
tensors.append(x)
t1 = time.time()
print(f' {len(sizes)} allocs: {(t1-t0)*1000:.1f}ms')
print('Free all:')
del tensors
torch.cuda.synchronize()
t2 = time.time()
print(f' {len(sizes)} frees: {(t2-t1)*1000:.1f}ms')
print('Second pass (warm cache - should be faster):')
tensors2 = []
for s in sizes:
x = torch.empty(s // 2, dtype=torch.float16, device='cuda')
tensors2.append(x)
t3 = time.time()
print(f' {len(sizes)} allocs: {(t3-t2)*1000:.1f}ms')
print('Third pass (reuse same sizes 100x):')
for _ in range(100):
for s in sizes:
x = torch.empty(s // 2, dtype=torch.float16, device='cuda')
del x
t4 = time.time()
print(f' 700 alloc+free: {(t4-t3)*1000:.1f}ms ({(t4-t3)/700*1000000:.0f}μs/op)')
" 2>&1
echo ""
echo "=== Step 4: Large allocation test (model weights sized) ==="
CCCL_ALLOC_DEBUG=0 LD_PRELOAD="$SO" python3 -c "
import torch
# Simulate KV cache blocks (typical: 256KB-2MB each)
blocks = []
for i in range(100):
b = torch.empty(256*1024 // 2, dtype=torch.float16, device='cuda')
blocks.append(b)
print(f'Allocated 100 x 256KB blocks = {100*256/1024:.0f}MB')
del blocks
torch.cuda.synchronize()
print('Freed all blocks')
# Reallocate (should hit cache)
blocks2 = []
for i in range(100):
b = torch.empty(256*1024 // 2, dtype=torch.float16, device='cuda')
blocks2.append(b)
print('Re-allocated 100 blocks (from cache)')
print('OK: large allocation test passed')
" 2>&1
echo ""
echo "=== Step 5: Stats output ==="
CCCL_ALLOC_DEBUG=0 LD_PRELOAD="$SO" python3 -c "
import torch
for _ in range(50):
x = torch.zeros(1024*1024, device='cuda')
del x
# Stats print on process exit
" 2>&1
echo ""
echo "=== DONE ==="
echo "If all tests passed, add to your launch command:"
echo " LD_PRELOAD=$SO python3 -m vllm.entrypoints.openai.api_server ..."
echo ""
echo "Or set in computility-run.yaml env:"
echo " - name: LD_PRELOAD"
echo " value: /workspace/qwen3_6_scripts/cccl_preload_allocator.so"