Made a fused GEMV kernel for convrot unpacking to increase speed further. Fix bug in test script that made train time add additional grads to bf16.

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Jaret Burkett committed 2026-07-15 10:24:52 -06:00
1 parent 691ddf434e
commit e28727d5cb
3 files changed
+631 -114

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@@ -6,10 +6,13 @@ Compares bf16 against the custom OstrisLinear backends (convrot8, convrot4 for
now; add more qtypes to QTYPES as they land).
Measures, per qtype:
- layer inference latency across DiT-representative shapes (vs bf16)
- layer training latency (forward + backward through the frozen layer)
- layer inference latency across DiT-representative shapes (vs bf16),
eager and torch.compile'd
- layer training latency (forward + backward through the frozen layer),
eager and torch.compile'd
- VRAM on a transformer-ish block stack: resident weights, peak during a
no-grad forward, peak during a train step
no-grad forward, peak during a train step; forward/train-ckpt peaks also
under torch.compile
- accuracy drift vs bf16: output relative error per layer shape and
accumulated through the block stack
- weight reconstruction error and one-time quantize (conversion) time
@@ -46,7 +49,7 @@ VRAM_BLOCK_SHAPES = [(3072, 12288), (12288, 3072), (3072, 3072), (3072, 3072)]
VRAM_TOKENS = 4096
QTYPES = [
"bf16", "qfloat8", "float8", "orbit4", "orbitvq4", "convrot8", "convrot4",
"bf16", "qfloat8", "float8", "convrot8", "convrot4",
"convrotint7", "convrotint6", "convrotint5", "convrotint4", "convrotint3",
"convrotint2", "convrotbitnet", "convrotcomfyw4a4",
]
@@ -106,6 +109,10 @@ def make_layer(k: int, n: int, device) -> torch.nn.Linear:
lin = torch.nn.Linear(k, n, bias=True, dtype=torch.bfloat16, device=device)
with torch.no_grad():
lin.weight.mul_(0.02)
# the train benches model lora-style training: base frozen, grads flow to
# the input only. without this, bf16/quanto accumulate weight grads that
# inflate every later vram measurement
lin.requires_grad_(False)
return lin
@@ -120,6 +127,8 @@ def make_stack(device) -> torch.nn.ModuleList:
torch.nn.Linear(k, n, bias=True, dtype=torch.bfloat16, device=device)
for k, n in VRAM_BLOCK_SHAPES
]))
# frozen base (see make_layer)
blocks.requires_grad_(False)
return blocks
@@ -163,9 +172,59 @@ def run_speed(qtype: str, device, iters: int, results: dict):
t_train = bench(train_step, max(10, iters // 3), device)
results[(qtype, "inf", (m, k, n))] = t_inf
results[(qtype, "train", (m, k, n))] = t_train
# compiled variants (compilation happens during bench warmup, so it
# isn't charged to the timing; a backend that won't compile records
# nothing and shows as '-')
lin_c = torch.compile(lin, dynamic=False)
try:
with torch.no_grad():
results[(qtype, "inf_comp", (m, k, n))] = bench(
lambda: lin_c(x), iters, device
)
except Exception as e:
print(f" [{qtype}] compiled inference failed for {m}x{k}->{n}: {e}")
def train_step_c():
xi = x.detach().requires_grad_(True)
lin_c(xi).sum().backward()
try:
results[(qtype, "train_comp", (m, k, n))] = bench(
train_step_c, max(10, iters // 3), device
)
except Exception as e:
print(f" [{qtype}] compiled train failed for {m}x{k}->{n}: {e}")
torch.cuda.empty_cache()
def _stack_fwd_peak(blocks, x, device, base) -> int:
# warm up first so lazy-init allocations (and compilation) are not counted
# as steady-state peak
with torch.no_grad():
stack_forward(blocks, x)
torch.cuda.synchronize(device)
torch.cuda.reset_peak_memory_stats(device)
with torch.no_grad():
stack_forward(blocks, x)
torch.cuda.synchronize(device)
return torch.cuda.max_memory_allocated(device) - base
def _stack_train_peak(blocks, x, device, base, checkpoint) -> int:
# frozen base; grads flow to the input like lora training
def train_step():
xi = x.detach().requires_grad_(True)
stack_forward(blocks, xi, checkpoint).float().pow(2).mean().backward()
train_step()
torch.cuda.synchronize(device)
torch.cuda.reset_peak_memory_stats(device)
train_step()
torch.cuda.synchronize(device)
return torch.cuda.max_memory_allocated(device) - base
def run_vram(qtype: str, device, results: dict):
torch.cuda.empty_cache()
base = torch.cuda.memory_allocated(device)
@@ -179,30 +238,22 @@ def run_vram(qtype: str, device, results: dict):
x = torch.randn(VRAM_TOKENS, 3072, device=device, dtype=torch.bfloat16)
# no-grad forward peak (sampling); warm up first so lazy-init allocations are
# not counted as steady-state peak
with torch.no_grad():
stack_forward(blocks, x)
torch.cuda.synchronize(device)
torch.cuda.reset_peak_memory_stats(device)
with torch.no_grad():
stack_forward(blocks, x)
torch.cuda.synchronize(device)
results[(qtype, "vram_fwd_peak")] = torch.cuda.max_memory_allocated(device) - base
results[(qtype, "vram_fwd_peak")] = _stack_fwd_peak(blocks, x, device, base)
# real training checkpoints, but the plain train peak still gets reported
results[(qtype, "vram_train_peak")] = _stack_train_peak(blocks, x, device, base, False)
results[(qtype, "vram_train_ckpt_peak")] = _stack_train_peak(blocks, x, device, base, True)
# train step peak (frozen base; grads flow to the input like lora training),
# with and without per-block gradient checkpointing (real training uses it)
def train_step(checkpoint):
xi = x.detach().requires_grad_(True)
stack_forward(blocks, xi, checkpoint).float().pow(2).mean().backward()
for key, ckpt in (("vram_train_peak", False), ("vram_train_ckpt_peak", True)):
train_step(ckpt)
torch.cuda.synchronize(device)
torch.cuda.reset_peak_memory_stats(device)
train_step(ckpt)
torch.cuda.synchronize(device)
results[(qtype, key)] = torch.cuda.max_memory_allocated(device) - base
# same peaks with every linear compiled (mirrors the trainer's block compile)
for b in blocks:
for i in range(len(b)):
b[i] = torch.compile(b[i], dynamic=False)
try:
results[(qtype, "vram_fwd_peak_comp")] = _stack_fwd_peak(blocks, x, device, base)
results[(qtype, "vram_train_ckpt_peak_comp")] = _stack_train_peak(
blocks, x, device, base, True
)
except Exception as e:
print(f" [{qtype}] compiled vram measurement failed: {e}")
blocks = x = None # release before the allocator accounting of the next run
torch.cuda.empty_cache()
@@ -252,18 +303,22 @@ def run_quality_and_quantize_time(qtype: str, device, results: dict):
def print_speed_table(title: str, kind: str, qts, results):
print(f"\n=== {title} (ms; speedup vs bf16) ===")
# speedups always reference EAGER bf16, compiled kinds included, so the
# comp columns answer "what do I gain over plain bf16"
ref_kind = kind.removesuffix("_comp")
print(f"\n=== {title} (ms; speedup vs eager bf16) ===")
print(f"{'M x K -> N':<22}" + "".join(f"{qt:>18}" for qt in qts))
for shape in SPEED_SHAPES:
m, k, n = shape
row = f"{f'{m} x {k} -> {n}':<22}"
ref = results.get(("bf16", kind, shape))
ref = results.get(("bf16", ref_kind, shape))
for qt in qts:
t = results.get((qt, kind, shape))
if t is None:
row += f"{'-':>18}"
continue
sp = f" ({ref / t:4.2f}x)" if ref and qt != "bf16" else " " * 8
is_self_ref = qt == "bf16" and kind == ref_kind
sp = f" ({ref / t:4.2f}x)" if ref and not is_self_ref else " " * 8
row += f"{t:8.3f}ms{sp}"
print(row)
@@ -290,9 +345,15 @@ def main():
if qt != "bf16":
get_ostris_quantizer(qt)
# many distinct module instances share one forward code object; the default
# per-code cache limit (8) would silently fall back to eager and corrupt the
# compiled columns
torch._dynamo.config.cache_size_limit = 4096
results = {}
for qt in args.qtypes:
print(f"benchmarking {qt} ...")
torch._dynamo.reset() # drop the previous qtype's compiled artifacts
run_quality_and_quantize_time(qt, device, results)
run_drift(qt, device, results)
run_speed(qt, device, args.iters, results)
@@ -300,17 +361,22 @@ def main():
qts = args.qtypes
print_speed_table("layer latency, inference", "inf", qts, results)
print_speed_table("layer latency, inference (compiled)", "inf_comp", qts, results)
print_speed_table("layer latency, train fwd+bwd", "train", qts, results)
print_speed_table("layer latency, train fwd+bwd (compiled)", "train_comp", qts, results)
print(f"\n=== vram on the block stack ({VRAM_BLOCKS} blocks, {VRAM_TOKENS} tokens) ===")
print(f"{'':<28}" + "".join(f"{qt:>18}" for qt in qts))
for key, label in (("vram_weights", "weights resident"),
("vram_fwd_peak", "peak, no-grad fwd"),
("vram_train_peak", "peak, train step"),
("vram_train_ckpt_peak", "peak, train step (ckpt)")):
("vram_train_ckpt_peak", "peak, train step (ckpt)"),
("vram_fwd_peak_comp", "peak, no-grad fwd (comp)"),
("vram_train_ckpt_peak_comp", "peak, train ckpt (comp)")):
row = f"{label:<28}"
for qt in qts:
row += f"{gb(results[(qt, key)]):>18}"
v = results.get((qt, key))
row += f"{gb(v):>18}" if v is not None else f"{'-':>18}"
print(row)
print("\n=== accuracy drift vs bf16 (output rel err, no-grad) ===")
@@ -335,25 +401,38 @@ def main():
# ---- clean per-qtype breakdown: speed (geomean over shapes) + accuracy ----
def geomean_speedup(qt, kind):
# every speedup references EAGER bf16 (compiled kinds included), so the
# comp columns answer "what do I gain over plain bf16"
ref_kind = kind.removesuffix("_comp")
logs = []
for shape in SPEED_SHAPES:
ref = results.get(("bf16", kind, shape))
ref = results.get(("bf16", ref_kind, shape))
t = results.get((qt, kind, shape))
if ref and t:
logs.append(math.log(ref / t))
return math.exp(sum(logs) / len(logs)) if logs else float("nan")
return math.exp(sum(logs) / len(logs)) if logs else None
def fmt_speed(v):
return f"{v:.2f}x" if v is not None else "-"
print("\n=== summary (speed = geomean speedup vs bf16; drift lower is better) ===")
print(f"{'':<12}{'inference':>18}{'train':>18}{'accuracy drift':>20}{'max vram':>16}")
print(f"{'':<18}{'inference':>12}{'inference comp':>16}{'train':>12}{'train comp':>12}"
f"{'accuracy drift':>16}{'max vram':>12}{'max vram comp':>15}")
for qt in qts:
# real training checkpoints, so the ckpt peak is the meaningful train
# number; the no-grad fwd peak still matters for sampling
max_vram = max(results[(qt, "vram_fwd_peak")], results[(qt, "vram_train_ckpt_peak")])
print(f"{qt:<12}"
f"{geomean_speedup(qt, 'inf'):>17.2f}x"
f"{geomean_speedup(qt, 'train'):>17.2f}x"
f"{results[(qt, 'drift', STACK_KEY)]:>20.5f}"
f"{gb(max_vram):>16}")
fwd_c = results.get((qt, "vram_fwd_peak_comp"))
ckpt_c = results.get((qt, "vram_train_ckpt_peak_comp"))
max_vram_comp = max(fwd_c, ckpt_c) if fwd_c is not None and ckpt_c is not None else None
print(f"{qt:<18}"
f"{fmt_speed(geomean_speedup(qt, 'inf')):>12}"
f"{fmt_speed(geomean_speedup(qt, 'inf_comp')):>16}"
f"{fmt_speed(geomean_speedup(qt, 'train')):>12}"
f"{fmt_speed(geomean_speedup(qt, 'train_comp')):>12}"
f"{results[(qt, 'drift', STACK_KEY)]:>16.5f}"
f"{gb(max_vram).strip():>12}"
f"{(gb(max_vram_comp).strip() if max_vram_comp is not None else '-'):>15}")
if __name__ == "__main__":