Files
mlx/python/tests/mlx_distributed_tests.py
Anastasiia Filippova 27778156dc Nccl reduce scatter, all gather (#2727)
* Added reduce scatter and all gather for nccl

* fix unused import, delete unused file

* small fix

* deleted useless condition

* fixed comments

* fix bug in eval_gpu, renamed to sum_scatter, fix docs

* final fix docs

* remove and

* Update mlx/distributed/mpi/mpi.cpp

Co-authored-by: Awni Hannun <awni.hannun@gmail.com>

* fix broken set input output

* fixes set output

* typo

* fix typo

* no cpu, no gpu for reduce scatter

---------

Co-authored-by: Awni Hannun <awni.hannun@gmail.com>
2025-11-05 08:21:11 -08:00

315 lines
9.7 KiB
Python

# Copyright © 2025 Apple Inc.
import mlx.core as mx
import mlx.nn as nn
import mlx_tests
from mlx.nn.layers.distributed import shard_inplace, shard_linear
from mlx.nn.utils import average_gradients
class MLXDistributedCommonTestCase(mlx_tests.MLXTestCase):
def test_average_gradients(self):
original_all_sum = mx.distributed.all_sum
n_calls = 0
xtype = None
def new_all_sum(x, **kwargs):
nonlocal n_calls
nonlocal xtype
n_calls += 1
if xtype is not None:
self.assertEqual(xtype, x.dtype)
return original_all_sum(x, **kwargs)
mx.distributed.all_sum = new_all_sum
try:
grads = [mx.ones(10) for i in range(10)]
new_grads = average_gradients(grads)
mx.eval(new_grads)
self.assertEqual(len(new_grads), 10)
self.assertTrue(all(mx.all(g == 1) for g in new_grads))
self.assertEqual(n_calls, 1)
n_calls = 0
new_grads = average_gradients(grads, all_reduce_size=4 * 50)
mx.eval(new_grads)
self.assertEqual(len(new_grads), 10)
self.assertTrue(all(mx.all(g == 1) for g in new_grads))
self.assertEqual(n_calls, 2)
n_calls = 0
new_grads = average_gradients(grads, all_reduce_size=0)
mx.eval(new_grads)
self.assertEqual(len(new_grads), 10)
self.assertTrue(all(mx.all(g == 1) for g in new_grads))
self.assertEqual(n_calls, 10)
n_calls = 0
xtype = mx.float16
new_grads = average_gradients(
grads, all_reduce_size=2 * 50, communication_type=mx.float16
)
mx.eval(new_grads)
self.assertEqual(len(new_grads), 10)
self.assertTrue(all(g.dtype == mx.float32 for g in new_grads))
self.assertTrue(all(mx.all(g == 1) for g in new_grads))
self.assertEqual(n_calls, 2)
finally:
mx.distributed.all_sum = original_all_sum
def test_all_reduce(self):
g = mx.distributed.init()
dtypes = [
(mx.int8, 0),
(mx.uint8, 0),
(mx.int32, 0),
(mx.uint32, 0),
(mx.float32, 1e-6),
(mx.float16, 5e-3),
(mx.bfloat16, 1e-1),
]
sizes = [
(7,),
(10,),
(1024,),
(1024, 1024),
]
key = mx.random.key(0)
for dt, rtol in dtypes:
for sh in sizes:
x = (mx.random.uniform(shape=(g.size(),) + sh, key=key) * 10).astype(dt)
# All sum
y = mx.distributed.all_sum(x[g.rank()], group=g)
z = x.sum(0)
maxrelerror = (y - z).abs()
if rtol > 0:
maxrelerror /= z.abs()
maxrelerror = maxrelerror.max()
self.assertLessEqual(maxrelerror, rtol)
# All max
y = mx.distributed.all_max(x[g.rank()], group=g)
z = x.max(0)
self.assertTrue(mx.all(y == z))
# All min
y = mx.distributed.all_min(x[g.rank()], group=g)
z = x.min(0)
self.assertTrue(mx.all(y == z))
def test_donation(self):
x = mx.random.normal((1024,))
mx.eval(x)
mx.synchronize()
mx.reset_peak_memory()
scale = mx.array(2.0)
y = mx.distributed.all_sum(x)
mx.eval(y)
mx.synchronize()
all_sum_only = mx.get_peak_memory()
y = mx.distributed.all_sum(x) * scale
mx.eval(y)
mx.synchronize()
all_sum_with_binary = mx.get_peak_memory()
self.assertEqual(all_sum_only, all_sum_with_binary)
def test_shard_linear(self):
# Seed the prng to have the same inputs and weights generated everywhere
mx.random.seed(0xF0F0F0F0)
# Prepare inputs
world = mx.distributed.init()
part = (
slice(None),
slice(
world.rank() * 1024 // world.size(),
(world.rank() + 1) * 1024 // world.size(),
),
)
x = mx.random.normal((4, 1024))
# Create and shard some linear layers
lin = nn.Linear(1024, 1024, bias=True)
slin1 = shard_linear(lin, "all-to-sharded")
slin2 = shard_linear(lin, "sharded-to-all")
y = lin(x)
y1 = slin1(x)
y2 = slin2(x[part])
self.assertTrue(mx.allclose(y, y2, atol=self.atol, rtol=self.rtol))
self.assertTrue(mx.allclose(y[part], y1, atol=self.atol, rtol=self.rtol))
# And their quant versions (QuintizedMatmul is not supported on CUDA)
if not mx.cuda.is_available():
qlin = lin.to_quantized()
slin1 = shard_linear(qlin, "all-to-sharded")
slin2 = shard_linear(qlin, "sharded-to-all")
y = qlin(x)
y1 = slin1(x)
y2 = slin2(x[part])
self.assertTrue(mx.allclose(y, y2, atol=self.atol, rtol=self.rtol))
self.assertTrue(mx.allclose(y[part], y1))
# Check the backward works as expected
def dummy_loss(model, x, y):
return (model(x) * y).sum()
mod = nn.Sequential(
nn.Linear(128, 128),
nn.Linear(128, 128),
nn.Linear(128, 128),
nn.Linear(128, 128),
)
smod = nn.Sequential(
shard_linear(mod.layers[0], "all-to-sharded"),
shard_linear(mod.layers[1], "sharded-to-all"),
shard_linear(mod.layers[2], "all-to-sharded"),
shard_linear(mod.layers[3], "sharded-to-all"),
)
grad1 = nn.value_and_grad(mod, dummy_loss)
grad2 = nn.value_and_grad(smod, dummy_loss)
x = mx.random.normal((4, 128))
y = mx.random.normal((4, 128))
l1, g1 = grad1(mod, x, y)
l2, g2 = grad2(smod, x, y)
mx.eval(l1, g1, l2, g2)
part = slice(
world.rank() * 128 // world.size(), (world.rank() + 1) * 128 // world.size()
)
self.assertTrue(mx.allclose(l1, l2))
self.assertTrue(
mx.allclose(
g1["layers"][0]["weight"][part],
g2["layers"][0]["weight"],
atol=1e-6,
rtol=1e-4,
)
)
self.assertTrue(
mx.allclose(
g1["layers"][2]["weight"][part],
g2["layers"][2]["weight"],
atol=1e-6,
rtol=1e-4,
)
)
self.assertTrue(
mx.allclose(
g1["layers"][1]["weight"][:, part],
g2["layers"][1]["weight"],
atol=1e-6,
rtol=1e-4,
)
)
self.assertTrue(
mx.allclose(
g1["layers"][3]["weight"][:, part],
g2["layers"][3]["weight"],
atol=1e-6,
rtol=1e-4,
)
)
self.assertTrue(
mx.allclose(
g1["layers"][0]["bias"][part],
g2["layers"][0]["bias"],
atol=1e-6,
rtol=1e-4,
)
)
self.assertTrue(
mx.allclose(
g1["layers"][2]["bias"][part],
g2["layers"][2]["bias"],
atol=1e-6,
rtol=1e-4,
)
)
self.assertTrue(
mx.allclose(
g1["layers"][1]["bias"],
g2["layers"][1]["bias"],
atol=self.atol,
rtol=self.rtol,
)
)
self.assertTrue(
mx.allclose(
g1["layers"][3]["bias"],
g2["layers"][3]["bias"],
atol=self.atol,
rtol=self.rtol,
)
)
def test_shard_predicate(self):
mx.random.seed(0xF0F0F0F0)
class MyConv(nn.Module):
def __init__(self, *args, **kwargs):
super().__init__()
self.aggregate = kwargs.pop("aggregate", False)
self.conv = nn.Conv2d(*args, **kwargs)
def __call__(self, x):
x = self.conv(x)
if self.aggregate:
x = mx.distributed.all_sum(x)
return x
def sharding(path, weight):
parts = path.split(".")
even = int(parts[1]) % 2 == 0
if even:
return 0
else:
return -1 if parts[-1] != "bias" else None
mod = nn.Sequential(
MyConv(3, 128, kernel_size=3),
MyConv(128, 128, kernel_size=3),
MyConv(128, 128, kernel_size=3),
MyConv(128, 3, kernel_size=3),
)
smod = nn.Sequential(
MyConv(3, 128, kernel_size=3),
MyConv(128, 128, kernel_size=3, aggregate=True),
MyConv(128, 128, kernel_size=3),
MyConv(128, 3, kernel_size=3, aggregate=True),
)
smod.update(mod.parameters())
shard_inplace(smod, sharding)
x = mx.random.normal((4, 16, 16, 3))
y1 = mod(x)
y2 = smod(x)
self.assertTrue(mx.allclose(y1, y2, atol=1e-6, rtol=1e-4))
def test_all_gather(self):
world = mx.distributed.init()
dtypes = [
mx.int8,
mx.uint8,
mx.int32,
mx.uint32,
mx.float32,
mx.float16,
mx.bfloat16,
]
for dt in dtypes:
x = mx.ones((2, 2, 4), dtype=dt)
y = mx.distributed.all_gather(x)
self.assertEqual(y.shape, (world.size() * 2, 2, 4))
self.assertTrue(mx.all(y == 1))