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
This commit is contained in:
Claude
2026-08-13 09:21:45 +00:00
parent a1ae6e366f
commit 327c2c9044
5 changed files with 639 additions and 0 deletions

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@@ -49,3 +49,13 @@ env:
value: '1'
- name: PYTORCH_CUDA_ALLOC_CONF
value: expandable_segments:True
- name: LD_PRELOAD
value: /workspace/qwen3_6_scripts/cccl_preload_allocator.so
- name: CCCL_ALLOC_BIN_GROWTH
value: '8'
- name: CCCL_ALLOC_MIN_BIN
value: '3'
- name: CCCL_ALLOC_MAX_BIN
value: '13'
- name: CCCL_ALLOC_MAX_CACHED_MB
value: '4096'

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@@ -0,0 +1,99 @@
#!/usr/bin/env bash
set -euo pipefail
# Build the CCCL CachingDeviceAllocator LD_PRELOAD .so
#
# Usage: bash build_cccl_preload_allocator.sh [output_dir]
# Default output: ./cccl_preload_allocator.so
#
# Test: LD_PRELOAD=./cccl_preload_allocator.so python3 -c "import torch; x=torch.zeros(1024,device='cuda'); del x; print('OK')"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
OUTPUT_DIR=${1:-${SCRIPT_DIR}}
OUTPUT=${OUTPUT_DIR}/cccl_preload_allocator.so
SOURCE=${SCRIPT_DIR}/cccl_preload_allocator.cu
COREX_ROOT=${COREX_ROOT:-/usr/local/corex-3.2.3}
# Check if we have the corex compiler
if [[ -x "${COREX_ROOT}/bin/clang++" ]]; then
COMPILER="${COREX_ROOT}/bin/clang++"
echo "[build] Using corex clang++: ${COMPILER}"
"${COMPILER}" \
-std=c++17 -O3 -shared -fPIC \
--cuda-path="${COREX_ROOT}" --cuda-gpu-arch=ivcore10 \
--no-cuda-version-check -D_GLIBCXX_USE_CXX11_ABI=0 \
-I"${COREX_ROOT}/include" \
"${SOURCE}" \
-L"${COREX_ROOT}/lib64" -lcudart -ldl \
-Wl,-rpath,"${COREX_ROOT}/lib64" \
-o "${OUTPUT}"
else
# Fallback: try to compile as pure C++ (no CUDA kernels needed)
# The allocator is entirely host-side code
echo "[build] corex clang++ not found, trying system g++"
echo "[build] Note: this is HOST-only code, no GPU kernels involved"
# Find cuda include path
CUDA_INC=""
for p in /usr/local/corex-3.2.3/include /usr/local/cuda/include /usr/local/corex/include; do
if [[ -d "$p" ]]; then CUDA_INC="$p"; break; fi
done
CUDA_LIB=""
for p in /usr/local/corex-3.2.3/lib64 /usr/local/cuda/lib64 /usr/local/corex/lib64; do
if [[ -d "$p" ]]; then CUDA_LIB="$p"; break; fi
done
if [[ -z "$CUDA_INC" || -z "$CUDA_LIB" ]]; then
echo "[build] ERROR: Cannot find CUDA headers/libs" >&2
exit 2
fi
# Rename .cu → .cpp for g++ (it's all host code anyway)
TMP_CPP=$(mktemp /tmp/cccl_alloc_XXXXXX.cpp)
cp "${SOURCE}" "${TMP_CPP}"
g++ -std=c++17 -O3 -shared -fPIC \
-D_GLIBCXX_USE_CXX11_ABI=0 \
-I"${CUDA_INC}" \
"${TMP_CPP}" \
-L"${CUDA_LIB}" -lcudart -ldl \
-Wl,-rpath,"${CUDA_LIB}" \
-o "${OUTPUT}"
rm -f "${TMP_CPP}"
fi
# Verify
if [[ ! -s "${OUTPUT}" ]]; then
echo "[build] ERROR: output is empty" >&2
exit 2
fi
# Check it's a proper shared library with our symbols
if command -v nm &>/dev/null; then
HAS_MALLOC=$(nm -D "${OUTPUT}" 2>/dev/null | grep -c "T cudaMalloc" || true)
HAS_FREE=$(nm -D "${OUTPUT}" 2>/dev/null | grep -c "T cudaFree" || true)
if [[ "$HAS_MALLOC" -gt 0 && "$HAS_FREE" -gt 0 ]]; then
echo "[build] OK: cudaMalloc and cudaFree symbols exported"
else
echo "[build] WARNING: symbol check inconclusive (nm output may differ)"
fi
fi
echo "[build] Built: ${OUTPUT} ($(stat -c%s "${OUTPUT}" 2>/dev/null || stat -f%z "${OUTPUT}") bytes)"
echo ""
echo "Test command:"
echo " LD_PRELOAD=${OUTPUT} python3 -c \"import torch; x=torch.zeros(1024,device='cuda'); del x; print('OK')\""
echo ""
echo "Production usage (add to computility-run.yaml or Dockerfile CMD):"
echo " LD_PRELOAD=${OUTPUT} python3 -m vllm.entrypoints.openai.api_server ..."
echo ""
echo "Tuning env vars:"
echo " CCCL_ALLOC_BIN_GROWTH=8 # Geometric growth factor"
echo " CCCL_ALLOC_MIN_BIN=3 # Min bin (growth^3 = 512B)"
echo " CCCL_ALLOC_MAX_BIN=13 # Max bin (8^13 = ~550MB)"
echo " CCCL_ALLOC_MAX_CACHED_MB=4096 # Max 4GB cached per device"
echo " CCCL_ALLOC_DEBUG=1 # Print every alloc/free"

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@@ -0,0 +1,405 @@
// cccl_preload_allocator.cu — LD_PRELOAD interception of cudaMalloc/cudaFree
//
// Replaces the default cudaMalloc/cudaFree with CCCL CUB CachingDeviceAllocator.
// This eliminates the CUDA driver's allocation overhead (cudaMalloc is slow on
// BI-V100: ~2-50ms per call) by reusing freed blocks from a bin-based cache.
//
// Build on BI-V100:
// /usr/local/corex-3.2.3/bin/clang++ -std=c++17 -O3 -shared -fPIC \
// --cuda-path=/usr/local/corex-3.2.3 --cuda-gpu-arch=ivcore10 \
// --no-cuda-version-check -D_GLIBCXX_USE_CXX11_ABI=0 \
// -I/usr/local/corex-3.2.3/include \
// cccl_preload_allocator.cu \
// -L/usr/local/corex-3.2.3/lib64 -lcudart -ldl \
// -o cccl_preload_allocator.so
//
// Usage:
// LD_PRELOAD=/workspace/qwen3_6_scripts/cccl_preload_allocator.so python3 -m vllm.entrypoints.openai.api_server ...
//
// Tuning (env vars):
// CCCL_ALLOC_BIN_GROWTH=8 Geometric growth factor (default 8)
// CCCL_ALLOC_MIN_BIN=3 Min bin exponent (default 3 → 512B)
// CCCL_ALLOC_MAX_BIN=13 Max bin exponent (default 13 → 512MB for growth=8; was 7→2MB)
// CCCL_ALLOC_MAX_CACHED_MB=4096 Max cached bytes per device in MB (default 4096=4GB)
// CCCL_ALLOC_DEBUG=0 Print alloc/free events (default 0)
//
// Design notes:
// - Only intercepts cudaMalloc and cudaFree (the synchronous variants).
// - cudaMallocAsync/cudaFreeAsync are NOT intercepted (PyTorch on BI-V100
// doesn't use them; the corex runtime may not support them).
// - Thread-safe via CUB's internal mutex.
// - Stream association: all allocations use the default stream (nullptr).
// PyTorch's CUDACachingAllocator handles stream ordering itself, so we
// don't need to track streams here.
// - Large allocations (> max_bin_bytes) pass through to real cudaMalloc.
// - The allocator is process-global (static singleton).
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <dlfcn.h>
#include <mutex>
#include <map>
#include <set>
#include <atomic>
// We inline the essential logic from CUB CachingDeviceAllocator rather than
// #include it, because the corex toolchain may not have full CCCL headers
// installed, and we need to link against corex's cudart, not NVIDIA's.
// Forward declare the real CUDA functions we'll dlsym
typedef int cudaError_t;
static constexpr cudaError_t cudaSuccess = 0;
typedef void* cudaStream_t;
typedef void* cudaEvent_t;
// Real function pointers (resolved via dlsym on first call)
using cudaMalloc_fn = cudaError_t(*)(void**, size_t);
using cudaFree_fn = cudaError_t(*)(void*);
using cudaGetDevice_fn = cudaError_t(*)(int*);
using cudaEventCreate_fn = cudaError_t(*)(cudaEvent_t*);
using cudaEventRecord_fn = cudaError_t(*)(cudaEvent_t, cudaStream_t);
using cudaEventQuery_fn = cudaError_t(*)(cudaEvent_t);
using cudaEventDestroy_fn = cudaError_t(*)(cudaEvent_t);
using cudaEventSynchronize_fn = cudaError_t(*)(cudaEvent_t);
static cudaMalloc_fn real_cudaMalloc = nullptr;
static cudaFree_fn real_cudaFree = nullptr;
static cudaGetDevice_fn real_cudaGetDevice = nullptr;
static cudaEventCreate_fn real_cudaEventCreate = nullptr;
static cudaEventRecord_fn real_cudaEventRecord = nullptr;
static cudaEventQuery_fn real_cudaEventQuery = nullptr;
static cudaEventDestroy_fn real_cudaEventDestroy = nullptr;
static cudaEventSynchronize_fn real_cudaEventSynchronize = nullptr;
static std::once_flag resolve_flag;
static void resolve_real_functions() {
real_cudaMalloc = (cudaMalloc_fn)dlsym(RTLD_NEXT, "cudaMalloc");
real_cudaFree = (cudaFree_fn)dlsym(RTLD_NEXT, "cudaFree");
real_cudaGetDevice = (cudaGetDevice_fn)dlsym(RTLD_NEXT, "cudaGetDevice");
real_cudaEventCreate = (cudaEventCreate_fn)dlsym(RTLD_NEXT, "cudaEventCreate");
real_cudaEventRecord = (cudaEventRecord_fn)dlsym(RTLD_NEXT, "cudaEventRecord");
real_cudaEventQuery = (cudaEventQuery_fn)dlsym(RTLD_NEXT, "cudaEventQuery");
real_cudaEventDestroy = (cudaEventDestroy_fn)dlsym(RTLD_NEXT, "cudaEventDestroy");
real_cudaEventSynchronize = (cudaEventSynchronize_fn)dlsym(RTLD_NEXT, "cudaEventSynchronize");
if (!real_cudaMalloc || !real_cudaFree) {
fprintf(stderr, "[CCCL_PRELOAD] FATAL: cannot resolve cudaMalloc/cudaFree via dlsym\n");
abort();
}
}
// ============================================================================
// Simplified CachingDeviceAllocator (from CCCL cub/util_allocator.cuh)
// Stripped to essentials: no debug logging macros, no CCCL config dependencies
// ============================================================================
struct BlockDescriptor {
void* d_ptr;
size_t bytes;
unsigned int bin;
int device;
cudaStream_t associated_stream;
cudaEvent_t ready_event;
BlockDescriptor(void* p, int dev)
: d_ptr(p), bytes(0), bin(~0u), device(dev),
associated_stream(nullptr), ready_event(nullptr) {}
BlockDescriptor(int dev)
: d_ptr(nullptr), bytes(0), bin(~0u), device(dev),
associated_stream(nullptr), ready_event(nullptr) {}
static bool PtrCompare(const BlockDescriptor& a, const BlockDescriptor& b) {
return (a.device == b.device) ? (a.d_ptr < b.d_ptr) : (a.device < b.device);
}
static bool SizeCompare(const BlockDescriptor& a, const BlockDescriptor& b) {
return (a.device == b.device) ? (a.bytes < b.bytes) : (a.device < b.device);
}
};
using Compare = bool(*)(const BlockDescriptor&, const BlockDescriptor&);
using CachedBlocks = std::multiset<BlockDescriptor, Compare>;
using BusyBlocks = std::multiset<BlockDescriptor, Compare>;
struct DeviceBytes { size_t free = 0; size_t live = 0; };
struct CachingAllocator {
std::mutex mtx;
unsigned int bin_growth;
unsigned int min_bin;
unsigned int max_bin;
size_t min_bin_bytes;
size_t max_bin_bytes;
size_t max_cached_bytes;
bool debug;
CachedBlocks cached_blocks;
BusyBlocks live_blocks;
std::map<int, DeviceBytes> cached_bytes;
// Stats
std::atomic<uint64_t> stat_hits{0};
std::atomic<uint64_t> stat_misses{0};
std::atomic<uint64_t> stat_frees{0};
std::atomic<uint64_t> stat_bypasses{0};
static unsigned int IntPow(unsigned int base, unsigned int exp) {
unsigned int r = 1;
while (exp > 0) {
if (exp & 1) r *= base;
base *= base;
exp >>= 1;
}
return r;
}
void NearestPowerOf(unsigned int& power, size_t& rounded,
unsigned int base, size_t value) {
power = 0; rounded = 1;
if (value * base < value) {
power = sizeof(size_t) * 8;
rounded = size_t(-1);
return;
}
while (rounded < value) { rounded *= base; power++; }
}
CachingAllocator()
: cached_blocks(BlockDescriptor::SizeCompare),
live_blocks(BlockDescriptor::PtrCompare) {
// Read config from env
auto env_or = [](const char* name, int def) -> int {
const char* v = getenv(name);
return v ? atoi(v) : def;
};
bin_growth = env_or("CCCL_ALLOC_BIN_GROWTH", 8);
min_bin = env_or("CCCL_ALLOC_MIN_BIN", 3);
max_bin = env_or("CCCL_ALLOC_MAX_BIN", 13);
int max_mb = env_or("CCCL_ALLOC_MAX_CACHED_MB", 4096);
debug = env_or("CCCL_ALLOC_DEBUG", 0) != 0;
min_bin_bytes = IntPow(bin_growth, min_bin);
max_bin_bytes = IntPow(bin_growth, max_bin);
max_cached_bytes = (size_t)max_mb * 1024ULL * 1024ULL;
fprintf(stderr, "[CCCL_PRELOAD] CachingDeviceAllocator: growth=%u "
"bins=[%u..%u] bin_bytes=[%zu..%zu] max_cached=%zuMB\n",
bin_growth, min_bin, max_bin,
min_bin_bytes, max_bin_bytes, max_cached_bytes / (1024*1024));
}
~CachingAllocator() {
fprintf(stderr, "[CCCL_PRELOAD] Stats: hits=%lu misses=%lu frees=%lu bypasses=%lu\n",
stat_hits.load(), stat_misses.load(),
stat_frees.load(), stat_bypasses.load());
// Free all cached blocks
for (auto& b : cached_blocks) {
if (b.ready_event) real_cudaEventDestroy(b.ready_event);
real_cudaFree(b.d_ptr);
}
}
cudaError_t Allocate(void** d_ptr, size_t bytes) {
std::call_once(resolve_flag, resolve_real_functions);
*d_ptr = nullptr;
// Get current device
int device = 0;
if (real_cudaGetDevice) real_cudaGetDevice(&device);
// Bin classification
unsigned int bin;
size_t rounded_bytes;
bool oversized = false;
if (bytes > max_bin_bytes) {
// Too large for caching — pass through
bin = max_bin + 1;
rounded_bytes = bytes;
oversized = true;
} else {
NearestPowerOf(bin, rounded_bytes, bin_growth, bytes);
if (bin < min_bin) {
bin = min_bin;
rounded_bytes = min_bin_bytes;
}
}
BlockDescriptor search_key(device);
search_key.bytes = rounded_bytes;
search_key.bin = bin;
// Lock
std::lock_guard<std::mutex> lock(mtx);
if (!oversized) {
// Search cached blocks for a match
auto range = cached_blocks.equal_range(search_key);
for (auto it = range.first; it != range.second; ++it) {
if (it->device == device && it->bin == bin) {
// Check if the stream work has completed
bool ready = true;
if (it->ready_event) {
cudaError_t ev_status = real_cudaEventQuery(it->ready_event);
if (ev_status != cudaSuccess) {
// Event not ready — try to synchronize briefly
// For BI-V100 with enforce_eager, events should be ready
real_cudaEventSynchronize(it->ready_event);
}
real_cudaEventDestroy(it->ready_event);
}
// Reuse this block
search_key.d_ptr = it->d_ptr;
search_key.bytes = it->bytes;
live_blocks.insert(search_key);
cached_bytes[device].free -= it->bytes;
cached_bytes[device].live += it->bytes;
cached_blocks.erase(it);
*d_ptr = search_key.d_ptr;
stat_hits++;
if (debug) {
fprintf(stderr, "[CCCL_PRELOAD] HIT dev=%d bin=%u "
"req=%zu alloc=%zu ptr=%p\n",
device, bin, bytes, search_key.bytes, *d_ptr);
}
return cudaSuccess;
}
}
}
// Cache miss — allocate new block
cudaError_t err = real_cudaMalloc(&search_key.d_ptr, rounded_bytes);
// If OOM, try evicting cached blocks and retry
if (err != cudaSuccess) {
// Free all cached blocks on this device
auto it = cached_blocks.begin();
while (it != cached_blocks.end()) {
if (it->device == device) {
if (it->ready_event) {
real_cudaEventSynchronize(it->ready_event);
real_cudaEventDestroy(it->ready_event);
}
real_cudaFree(it->d_ptr);
cached_bytes[device].free -= it->bytes;
it = cached_blocks.erase(it);
} else {
++it;
}
}
// Retry
err = real_cudaMalloc(&search_key.d_ptr, rounded_bytes);
}
if (err != cudaSuccess) {
return err;
}
search_key.bytes = rounded_bytes;
live_blocks.insert(search_key);
cached_bytes[device].live += rounded_bytes;
*d_ptr = search_key.d_ptr;
if (oversized) {
stat_bypasses++;
} else {
stat_misses++;
}
if (debug) {
fprintf(stderr, "[CCCL_PRELOAD] %s dev=%d bin=%u "
"req=%zu alloc=%zu ptr=%p\n",
oversized ? "PASS" : "MISS",
device, bin, bytes, rounded_bytes, *d_ptr);
}
return cudaSuccess;
}
cudaError_t Free(void* d_ptr) {
std::call_once(resolve_flag, resolve_real_functions);
if (d_ptr == nullptr) return cudaSuccess;
int device = 0;
if (real_cudaGetDevice) real_cudaGetDevice(&device);
BlockDescriptor search_key(d_ptr, device);
std::lock_guard<std::mutex> lock(mtx);
auto it = live_blocks.find(search_key);
if (it == live_blocks.end()) {
// Not tracked by us — pass through to real cudaFree
return real_cudaFree(d_ptr);
}
search_key.bytes = it->bytes;
search_key.bin = it->bin;
cached_bytes[device].live -= it->bytes;
live_blocks.erase(it);
stat_frees++;
// Check if this block is too large or would exceed cache limit
bool should_cache = (search_key.bin <= max_bin) &&
(cached_bytes[device].free + search_key.bytes <= max_cached_bytes);
if (should_cache) {
// Record an event so we know when it's safe to reuse
if (real_cudaEventCreate) {
cudaEvent_t event = nullptr;
cudaError_t ev_err = real_cudaEventCreate(&event);
if (ev_err == cudaSuccess && real_cudaEventRecord) {
real_cudaEventRecord(event, nullptr); // default stream
search_key.ready_event = event;
}
}
cached_blocks.insert(search_key);
cached_bytes[device].free += search_key.bytes;
if (debug) {
fprintf(stderr, "[CCCL_PRELOAD] CACHE dev=%d bin=%u "
"bytes=%zu cached_free=%zu\n",
device, search_key.bin, search_key.bytes,
cached_bytes[device].free);
}
return cudaSuccess;
} else {
// Don't cache — actually free
if (debug) {
fprintf(stderr, "[CCCL_PRELOAD] FREE dev=%d bin=%u bytes=%zu\n",
device, search_key.bin, search_key.bytes);
}
return real_cudaFree(d_ptr);
}
}
};
// Global singleton
static CachingAllocator& get_allocator() {
static CachingAllocator alloc;
return alloc;
}
// ============================================================================
// LD_PRELOAD interception points
// ============================================================================
extern "C" {
cudaError_t cudaMalloc(void** devPtr, size_t size) {
return get_allocator().Allocate(devPtr, size);
}
cudaError_t cudaFree(void* devPtr) {
return get_allocator().Free(devPtr);
}
} // extern "C"

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@@ -246,6 +246,10 @@ if source != installed:
raise SystemExit("runtime api_server overlay identity mismatch")
PY
build_stage "compiling CCCL CachingDeviceAllocator LD_PRELOAD module"
bash ./build_cccl_preload_allocator.sh /workspace/qwen3_6_scripts || \
echo "[WARN] CCCL preload allocator build failed — will use default allocator"
build_stage "compiling CoreX CUDA extensions (moe_index_combine + gdn_chunk_recurrent)"
if [[ -x /usr/local/corex-3.2.3/bin/clang++ ]]; then
bash ./build_corex_moe_index_combine.sh "${VLLM_ROOT}" || \

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@@ -0,0 +1,121 @@
#!/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"