Files
axolotl/benchmarks/bench_scattermoe_lora.py
2026-03-19 07:27:23 +00:00

285 lines
9.1 KiB
Python

"""Benchmark for ScatterMoE LoRA Triton kernels.
Measures forward, backward dX, and backward dA/dB kernels at common MoE
model shapes. Reports per-kernel timings, LoRA overhead vs base scatter2scatter,
and full fwd+bwd autograd throughput.
Usage:
CUDA_VISIBLE_DEVICES=0 python benchmarks/bench_scattermoe_lora.py
CUDA_VISIBLE_DEVICES=0 python benchmarks/bench_scattermoe_lora.py --ranks 16 64
CUDA_VISIBLE_DEVICES=0 python benchmarks/bench_scattermoe_lora.py --models Qwen/Qwen3.5-35B-A3B
"""
import argparse
import gc
import time
from functools import partial
import torch
from axolotl.integrations.kernels.libs.scattermoe_lora.kernels import (
lora_ops,
ops as base_ops,
)
from axolotl.integrations.kernels.libs.scattermoe_lora.parallel_experts import (
flatten_sort_count,
)
from axolotl.integrations.kernels.libs.scattermoe_lora.parallel_linear_lora import (
ScatterMoELoRA,
)
DEVICE = "cuda"
DTYPE = torch.bfloat16
WARMUP = 5
ITERS = 20
# ─── Model configs ──────────────────────────────────────────────────────────
BUILTIN_CONFIGS = {
"Qwen3.5-35B-A3B": (256, 2048, 512, 8), # E, H, I, k
"Qwen3-30B-A3B": (128, 2048, 768, 8),
"OLMoE-1B-7B": (64, 2048, 1024, 8),
"Mixtral-8x7B": (8, 4096, 14336, 2),
}
def _resolve_config(spec):
"""Resolve a model spec to (E, H, I, k). Accepts builtin names or HF IDs."""
key = spec.lower().replace("/", "-")
for name, cfg in BUILTIN_CONFIGS.items():
if key in name.lower() or name.lower() in key:
return name, cfg
from transformers import AutoConfig
hf_cfg = AutoConfig.from_pretrained(spec, trust_remote_code=True)
if callable(getattr(hf_cfg, "get_text_config", None)):
tc = hf_cfg.get_text_config()
if hasattr(tc, "model_type") and tc.model_type != hf_cfg.model_type:
hf_cfg = tc
hidden = hf_cfg.hidden_size
inter = getattr(hf_cfg, "moe_intermediate_size", None) or hf_cfg.intermediate_size
experts = (
getattr(hf_cfg, "num_experts", None)
or getattr(hf_cfg, "num_local_experts", None)
or getattr(hf_cfg, "n_routed_experts", None)
)
top_k = (
getattr(hf_cfg, "num_experts_per_tok", None)
or getattr(hf_cfg, "num_experts_per_token", None)
or 2
)
name = spec.split("/")[-1]
return name, (experts, hidden, inter, top_k)
# ─── Benchmark helpers ──────────────────────────────────────────────────────
def _clean():
gc.collect()
torch.cuda.empty_cache()
torch.cuda.synchronize()
def _bench(fn, warmup=WARMUP, iters=ITERS):
for _ in range(warmup):
fn()
torch.cuda.synchronize()
times = []
for _ in range(iters):
torch.cuda.synchronize()
t0 = time.perf_counter()
fn()
torch.cuda.synchronize()
times.append((time.perf_counter() - t0) * 1000)
times.sort()
return times[len(times) // 2]
def _setup(num_experts, K, N, T, top_k, R):
torch.manual_seed(42)
x = torch.randn(T, K, device=DEVICE, dtype=DTYPE)
W = torch.randn(num_experts, K, N, device=DEVICE, dtype=DTYPE) * 0.02
lora_A = torch.randn(R * num_experts, K, device=DEVICE, dtype=DTYPE) * 0.01
lora_B = torch.randn(N, R * num_experts, device=DEVICE, dtype=DTYPE) * 0.01
logits = torch.randn(T, num_experts, device=DEVICE)
_, top_idx = torch.topk(torch.softmax(logits, dim=-1), top_k, dim=-1)
sei, ssi, eo = flatten_sort_count(top_idx, num_experts)
gx = base_ops.group(x, ssi, fan_out=top_k)
dy = torch.randn(gx.size(0), N, device=DEVICE, dtype=DTYPE)
return x, W, lora_A, lora_B, sei, ssi, eo, gx, dy
# ─── Kernel wrappers (avoid B023 loop-variable capture) ──────────────────────
def _call_fwd(x, W, sei, ssi, top_k, lA, lB):
return lora_ops.scatter2scatter_lora(
X=x,
W=W,
sorted_expert_idxs=sei,
sorted_scattered_idxs=ssi,
k=top_k,
lora_A=lA,
lora_B=lB,
scaling=2.0,
)
def _call_base(x, W, sei, ssi, top_k):
return base_ops.scatter2scatter(
X=x,
W=W,
sorted_expert_idxs=sei,
sorted_scattered_idxs=ssi,
k=top_k,
)
def _call_dx(dy, W, sei, ssi, lA, lB):
return lora_ops.scatter2scatter_lora_dX(
DY=dy,
W=W,
sorted_expert_idxs=sei,
sorted_scattered_idxs=ssi,
k=1,
lora_A=lA,
lora_B=lB,
scaling=2.0,
dy_grouped=True,
dx_grouped=False,
)
def _call_bwd(dy, gx, lA, lB, eo, num_experts):
return lora_ops.group_bwd_lora(
DY=dy,
X=gx,
lora_A=lA,
lora_B=lB,
expert_offsets=eo,
E=num_experts,
scaling=2.0,
)
# ─── Main ────────────────────────────────────────────────────────────────────
def main():
parser = argparse.ArgumentParser(description="ScatterMoE LoRA kernel benchmark")
parser.add_argument(
"--models",
"-m",
nargs="+",
help="Model names or HF IDs (default: all builtins)",
)
parser.add_argument("--ranks", "-r", nargs="+", type=int, default=[16, 32, 64])
parser.add_argument("--seq-len", "-T", type=int, default=2048)
args = parser.parse_args()
T = args.seq_len
print(f"GPU: {torch.cuda.get_device_name()}")
print(f"T={T}, ranks={args.ranks}\n")
if args.models:
configs = [_resolve_config(m) for m in args.models]
else:
configs = list(BUILTIN_CONFIGS.items())
for model_name, (num_experts, hidden, inter, top_k) in configs:
print(f"{'=' * 70}")
print(f" {model_name}: E={num_experts}, H={hidden}, I={inter}, k={top_k}")
print(f"{'=' * 70}")
for R in args.ranks:
for proj, K, N in [("gate_up", hidden, 2 * inter), ("down", inter, hidden)]:
_clean()
x, W, lA, lB, sei, ssi, eo, gx, dy = _setup(
num_experts, K, N, T, top_k, R
)
# Forward with LoRA (auto-dispatched: fused or split)
dispatch = (
"split"
if (
num_experts <= lora_ops._SPLIT_LORA_FWD_MAX_EXPERTS
and K * N >= lora_ops._SPLIT_LORA_FWD_THRESHOLD
)
else "fused"
)
t_fwd = _bench(partial(_call_fwd, x, W, sei, ssi, top_k, lA, lB))
t_base = _bench(partial(_call_base, x, W, sei, ssi, top_k))
t_dx = _bench(partial(_call_dx, dy, W, sei, ssi, lA, lB))
t_bwd = _bench(partial(_call_bwd, dy, gx, lA, lB, eo, num_experts))
total = t_fwd + t_dx + t_bwd
overhead = t_fwd / t_base - 1 if t_base > 0 else 0
print(
f" R={R:>2} {proj:<8} "
f"fwd={t_fwd:>6.2f}ms [{dispatch}] "
f"base={t_base:>6.2f}ms "
f"(+{overhead * 100:.0f}%) "
f"dx={t_dx:>6.2f}ms bwd={t_bwd:>6.2f}ms "
f"total={total:>6.2f}ms"
)
# Full autograd fwd+bwd with memory measurement
x_ag = x.clone().requires_grad_(True)
lA_ag = lA.clone().requires_grad_(True)
lB_ag = lB.clone().requires_grad_(True)
def _run_autograd(
_x=x_ag,
_W=W,
_k=top_k,
_sei=sei,
_ssi=ssi,
_eo=eo,
_lA=lA_ag,
_lB=lB_ag,
):
out = ScatterMoELoRA.apply(
_x,
_W,
_k,
_sei,
_ssi,
_eo,
_lA,
_lB,
2.0,
None,
None,
False,
False,
True,
False,
)
out.sum().backward()
_x.grad = None
_lA.grad = None
_lB.grad = None
t_full = _bench(_run_autograd)
_clean()
torch.cuda.reset_peak_memory_stats()
mem_before = torch.cuda.memory_allocated()
_run_autograd()
torch.cuda.synchronize()
mem_peak = torch.cuda.max_memory_allocated() - mem_before
print(
f" full_fwd_bwd={t_full:>6.2f}ms "
f"peak_delta={mem_peak / 1e6:>6.1f}MB"
)
print()
if __name__ == "__main__":
main()