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sglang/python/sglang/jit_kernel/benchmark/bench_hicache.py
Xuchun Shang 3d68bd9d9b add hicache jit test (#17847)
Signed-off-by: Xuchun Shang <xuchun.shang@linux.alibaba.com>
2026-02-06 16:54:33 +08:00

407 lines
11 KiB
Python

"""Benchmark for HiCache JIT kernel performance.
This benchmark tests the performance of KV cache transfer operations
between GPU and CPU (host pinned memory), comparing:
- SGL AOT Kernel: Pre-compiled transfer_kv kernels from sgl_kernel
- SGL JIT Kernel: JIT-compiled hicache kernels
- PyTorch Indexing: Plain PyTorch index copy
- PyTorch 2 Stream: PyTorch implementation using 2 CUDA streams
Tests cover:
- One Layer: CPU->GPU
- All Layer: GPU->CPU
Note: Uses do_bench instead of do_bench_cudagraph since CUDA graph
capture doesn't support CPU-GPU memory transfers.
"""
import itertools
from typing import Tuple
import torch
import triton
import triton.testing
from sgl_kernel import transfer_kv_all_layer, transfer_kv_per_layer
from sglang.jit_kernel.benchmark.utils import (
DEFAULT_DTYPE,
DEFAULT_QUANTILES,
get_benchmark_range,
)
from sglang.jit_kernel.hicache import (
can_use_hicache_jit_kernel,
transfer_hicache_all_layer,
transfer_hicache_one_layer,
)
def sglang_aot_transfer_one(
k_cache_dst: torch.Tensor,
v_cache_dst: torch.Tensor,
indices_dst: torch.Tensor,
k_cache_src: torch.Tensor,
v_cache_src: torch.Tensor,
indices_src: torch.Tensor,
item_size: int,
) -> None:
"""SGL AOT Kernel for single layer transfer."""
transfer_kv_per_layer(
k_cache_src,
k_cache_dst,
v_cache_src,
v_cache_dst,
indices_src,
indices_dst,
item_size,
)
def sglang_jit_transfer_one(
k_cache_dst: torch.Tensor,
v_cache_dst: torch.Tensor,
indices_dst: torch.Tensor,
k_cache_src: torch.Tensor,
v_cache_src: torch.Tensor,
indices_src: torch.Tensor,
element_dim: int,
) -> None:
"""SGL JIT Kernel for single layer transfer."""
transfer_hicache_one_layer(
k_cache_dst,
v_cache_dst,
indices_dst,
k_cache_src,
v_cache_src,
indices_src,
element_dim=element_dim,
)
def sglang_aot_transfer_all(
k_ptrs_dst: torch.Tensor,
v_ptrs_dst: torch.Tensor,
indices_dst: torch.Tensor,
k_ptrs_src: torch.Tensor,
v_ptrs_src: torch.Tensor,
indices_src: torch.Tensor,
item_size: int,
num_layers: int,
) -> None:
"""SGL AOT Kernel for all layer transfer."""
transfer_kv_all_layer(
k_ptrs_src,
k_ptrs_dst,
v_ptrs_src,
v_ptrs_dst,
indices_src,
indices_dst,
item_size,
num_layers,
)
def sglang_jit_transfer_all(
k_ptrs_dst: torch.Tensor,
v_ptrs_dst: torch.Tensor,
indices_dst: torch.Tensor,
k_ptrs_src: torch.Tensor,
v_ptrs_src: torch.Tensor,
indices_src: torch.Tensor,
stride_bytes: int,
element_size: int,
) -> None:
"""SGL JIT Kernel for all layer transfer."""
transfer_hicache_all_layer(
k_ptrs_dst,
v_ptrs_dst,
indices_dst,
k_ptrs_src,
v_ptrs_src,
indices_src,
kv_cache_src_stride_bytes=stride_bytes,
kv_cache_dst_stride_bytes=stride_bytes,
element_size=element_size,
)
def pytorch_transfer(
k_cache_dst: torch.Tensor,
v_cache_dst: torch.Tensor,
indices_dst_on_dst: torch.Tensor,
k_cache_src: torch.Tensor,
v_cache_src: torch.Tensor,
indices_src_on_src: torch.Tensor,
) -> None:
"""PyTorch indexing baseline."""
dst_device = k_cache_dst.device
k_cache_dst[indices_dst_on_dst] = k_cache_src[indices_src_on_src].to(dst_device)
v_cache_dst[indices_dst_on_dst] = v_cache_src[indices_src_on_src].to(dst_device)
alt_stream = torch.cuda.Stream()
def torch_streams_transfer(
k_cache_dst: torch.Tensor,
v_cache_dst: torch.Tensor,
indices_dst_on_dst: torch.Tensor,
k_cache_src: torch.Tensor,
v_cache_src: torch.Tensor,
indices_src_on_src: torch.Tensor,
) -> None:
"""PyTorch 2 Stream baseline."""
dst_device = k_cache_dst.device
current_stream = torch.cuda.current_stream()
alt_stream.wait_stream(current_stream)
k_cache_dst[indices_dst_on_dst] = k_cache_src[indices_src_on_src].to(dst_device)
with torch.cuda.stream(alt_stream):
v_cache_dst[indices_dst_on_dst] = v_cache_src[indices_src_on_src].to(dst_device)
current_stream.wait_stream(alt_stream)
# Benchmark configuration
GPU_CACHE_SIZE = 32 * 1024 # 32K tokens on GPU
HOST_CACHE_SIZE = 128 * 1024 # 128K tokens on CPU
NUM_LAYERS = 8
BS_RANGE = get_benchmark_range(
full_range=[2**n for n in range(0, 15)],
ci_range=[16],
)
ELEMENT_SIZE_RANGE = get_benchmark_range(
full_range=[64, 128, 256, 512, 1024],
ci_range=[1024],
)
LINE_VALS = ["aot", "jit", "pytorch", "torch_streams"]
LINE_NAMES = ["SGL AOT Kernel", "SGL JIT Kernel", "PyTorch", "PyTorch 2 Stream"]
STYLES = [("orange", "-"), ("blue", "--"), ("red", ":"), ("green", "-.")]
CONFIGS = list(itertools.product(ELEMENT_SIZE_RANGE, BS_RANGE))
# =============================================================================
# One Layer Benchmarks
# =============================================================================
@triton.testing.perf_report(
triton.testing.Benchmark(
x_names=["element_size", "batch_size"],
x_vals=CONFIGS,
line_arg="provider",
line_vals=LINE_VALS,
line_names=LINE_NAMES,
styles=STYLES,
ylabel="us",
plot_name="hicache-one-layer-h2d",
args={},
)
)
def benchmark_one_layer_h2d(
element_size: int, batch_size: int, provider: str
) -> Tuple[float, float, float]:
"""One Layer: Host (CPU) -> Device (GPU)."""
k_cache_src = torch.randn(
(HOST_CACHE_SIZE, element_size),
dtype=DEFAULT_DTYPE,
device="cpu",
pin_memory=True,
)
v_cache_src = torch.randn(
(HOST_CACHE_SIZE, element_size),
dtype=DEFAULT_DTYPE,
device="cpu",
pin_memory=True,
)
k_cache_dst = torch.randn(
(GPU_CACHE_SIZE, element_size), dtype=DEFAULT_DTYPE, device="cuda"
)
v_cache_dst = torch.randn(
(GPU_CACHE_SIZE, element_size), dtype=DEFAULT_DTYPE, device="cuda"
)
indices_src_gpu = torch.randperm(HOST_CACHE_SIZE, device="cuda")[:batch_size]
indices_dst_gpu = torch.randperm(GPU_CACHE_SIZE, device="cuda")[:batch_size]
indices_src_cpu = indices_src_gpu.cpu()
torch.cuda.synchronize()
element_bytes = element_size * k_cache_src.element_size()
FN_MAP = {
"aot": lambda: sglang_aot_transfer_one(
k_cache_dst,
v_cache_dst,
indices_dst_gpu,
k_cache_src,
v_cache_src,
indices_src_gpu,
element_bytes,
),
"jit": lambda: sglang_jit_transfer_one(
k_cache_dst,
v_cache_dst,
indices_dst_gpu,
k_cache_src,
v_cache_src,
indices_src_gpu,
element_size,
),
"pytorch": lambda: pytorch_transfer(
k_cache_dst,
v_cache_dst,
indices_dst_gpu,
k_cache_src,
v_cache_src,
indices_src_cpu,
),
"torch_streams": lambda: torch_streams_transfer(
k_cache_dst,
v_cache_dst,
indices_dst_gpu,
k_cache_src,
v_cache_src,
indices_src_cpu,
),
}
if provider == "jit" and not can_use_hicache_jit_kernel(element_size=element_bytes):
return (float("nan"), float("nan"), float("nan"))
ms, min_ms, max_ms = triton.testing.do_bench(
FN_MAP[provider], quantiles=DEFAULT_QUANTILES
)
return 1000 * ms, 1000 * max_ms, 1000 * min_ms
# =============================================================================
# All Layer Benchmarks
# =============================================================================
def _create_ptr_tensor(tensors, device="cuda"):
"""Create a tensor of data pointers."""
return torch.tensor(
[t.data_ptr() for t in tensors],
dtype=torch.uint64,
device=device,
)
@triton.testing.perf_report(
triton.testing.Benchmark(
x_names=["element_size", "batch_size"],
x_vals=CONFIGS,
line_arg="provider",
line_vals=LINE_VALS,
line_names=LINE_NAMES,
styles=STYLES,
ylabel="us",
plot_name="hicache-all-layer-d2h",
args={},
)
)
def benchmark_all_layer_d2h(
element_size: int, batch_size: int, provider: str
) -> Tuple[float, float, float]:
"""All Layer: Device (GPU) -> Host (CPU)."""
k_caches_src = torch.randn(
(NUM_LAYERS, GPU_CACHE_SIZE, element_size), dtype=DEFAULT_DTYPE, device="cuda"
)
v_caches_src = torch.randn(
(NUM_LAYERS, GPU_CACHE_SIZE, element_size), dtype=DEFAULT_DTYPE, device="cuda"
)
k_caches_dst = torch.randn(
(NUM_LAYERS, HOST_CACHE_SIZE, element_size),
dtype=DEFAULT_DTYPE,
device="cpu",
pin_memory=True,
)
v_caches_dst = torch.randn(
(NUM_LAYERS, HOST_CACHE_SIZE, element_size),
dtype=DEFAULT_DTYPE,
device="cpu",
pin_memory=True,
)
indices_src_gpu = torch.randperm(GPU_CACHE_SIZE, device="cuda")[:batch_size]
indices_dst_gpu = torch.randperm(HOST_CACHE_SIZE, device="cuda")[:batch_size]
indices_dst_cpu = indices_dst_gpu.cpu()
torch.cuda.synchronize()
element_bytes = element_size * k_caches_src.element_size()
k_ptrs_src = _create_ptr_tensor([k_caches_src[i] for i in range(NUM_LAYERS)])
v_ptrs_src = _create_ptr_tensor([v_caches_src[i] for i in range(NUM_LAYERS)])
k_ptrs_dst = _create_ptr_tensor([k_caches_dst[i] for i in range(NUM_LAYERS)])
v_ptrs_dst = _create_ptr_tensor([v_caches_dst[i] for i in range(NUM_LAYERS)])
FN_MAP = {
"aot": lambda: sglang_aot_transfer_all(
k_ptrs_dst,
v_ptrs_dst,
indices_dst_gpu,
k_ptrs_src,
v_ptrs_src,
indices_src_gpu,
element_bytes,
NUM_LAYERS,
),
"jit": lambda: sglang_jit_transfer_all(
k_ptrs_dst,
v_ptrs_dst,
indices_dst_gpu,
k_ptrs_src,
v_ptrs_src,
indices_src_gpu,
element_bytes,
element_bytes,
),
"pytorch": lambda: [
pytorch_transfer(
k_caches_dst[i],
v_caches_dst[i],
indices_dst_cpu,
k_caches_src[i],
v_caches_src[i],
indices_src_gpu,
)
for i in range(NUM_LAYERS)
],
"torch_streams": lambda: [
torch_streams_transfer(
k_caches_dst[i],
v_caches_dst[i],
indices_dst_cpu,
k_caches_src[i],
v_caches_src[i],
indices_src_gpu,
)
for i in range(NUM_LAYERS)
],
}
if provider == "jit" and not can_use_hicache_jit_kernel(element_size=element_bytes):
return (float("nan"), float("nan"), float("nan"))
ms, min_ms, max_ms = triton.testing.do_bench(
FN_MAP[provider], quantiles=DEFAULT_QUANTILES
)
return (
1000 * ms / NUM_LAYERS,
1000 * max_ms / NUM_LAYERS,
1000 * min_ms / NUM_LAYERS,
)
if __name__ == "__main__":
print("=" * 60)
print("One Layer: Host -> Device (CPU -> GPU)")
print("=" * 60)
benchmark_one_layer_h2d.run(print_data=True)
print("\n" + "=" * 60)
print("All Layer: Device -> Host (GPU -> CPU) [per-layer avg]")
print("=" * 60)
benchmark_all_layer_d2h.run(print_data=True)