109 lines
3.8 KiB
Python
109 lines
3.8 KiB
Python
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# Copyright 2023 The JAX Authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Sharding utilities"""
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import itertools
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from typing import List, Sequence, Tuple, Union
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import numpy as np
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from jax._src.lib import xla_client as xc
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def get_num_ways_dim_sharded(
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hlo_sharding: xc.HloSharding) -> Tuple[Sequence[int], int]:
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if hlo_sharding.is_replicated(): # type: ignore
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return [], 1
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partitions = hlo_sharding.tile_assignment_dimensions()
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subgroup_types = hlo_sharding.subgroup_types()
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if subgroup_types == [xc.OpSharding.Type.REPLICATED]:
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replicate_on_last_tile_dim = True
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else:
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replicate_on_last_tile_dim = hlo_sharding.replicate_on_last_tile_dim()
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if subgroup_types:
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raise NotImplementedError(
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"Unhandled OpSharding type. Please open a bug report!")
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num_replicas = 1
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if replicate_on_last_tile_dim:
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num_replicas = partitions[-1]
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partitions = partitions[:-1]
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return partitions, num_replicas
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def is_op_sharding_replicated(op: Union[xc.OpSharding, xc.HloSharding]) -> bool:
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if isinstance(op, xc.OpSharding):
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op = xc.HloSharding.from_proto(op)
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if op.num_devices() == 1:
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return True
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return op.is_replicated() # type: ignore
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def are_op_shardings_equal(op1: Union[xc.OpSharding, xc.HloSharding],
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op2: Union[xc.OpSharding, xc.HloSharding]) -> bool:
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if id(op1) == id(op2):
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return True
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if is_op_sharding_replicated(op1) and is_op_sharding_replicated(op2):
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return True
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hc1 = xc.HloSharding.from_proto(op1) if isinstance(op1, xc.OpSharding) else op1
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hc2 = xc.HloSharding.from_proto(op2) if isinstance(op2, xc.OpSharding) else op2
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return hc1 == hc2
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_Index = Union[int, slice, Tuple[Union[int, slice], ...]]
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def op_sharding_to_numpy_indices(
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hlo_sharding: xc.HloSharding, shape: Sequence[int],
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num_devices: int) -> np.ndarray:
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indices = np.empty(num_devices, dtype=np.object_)
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# num_devices is required as an argument when hlo_sharding is
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# REPLICATED. `jax.device_count()` cannot be used because you can create
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# an opsharding with less number of devices than `jax.device_count()`.
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if is_op_sharding_replicated(hlo_sharding):
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indices.fill((slice(None),) * len(shape))
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return indices
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assert num_devices == hlo_sharding.num_devices()
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partitions, num_replicas = get_num_ways_dim_sharded(hlo_sharding)
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assert len(partitions) == len(shape), (len(partitions), len(shape))
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axis_indices: List[Sequence[_Index]] = []
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for dim, n_shards in zip(shape, partitions):
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if n_shards == 1:
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axis_indices.append([slice(None)])
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elif n_shards > 1:
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shard_size, ragged = divmod(dim, n_shards)
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assert not ragged, (dim, n_shards)
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axis_indices.append([slice(i * shard_size, (i + 1) * shard_size)
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for i in range(n_shards)])
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else:
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raise AssertionError('Unrecognized number of shards. Please file a bug!')
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device_it = iter(hlo_sharding.tile_assignment_devices())
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for i, idxs in enumerate(itertools.product(*axis_indices)):
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for _ in range(num_replicas):
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indices[next(device_it)] = idxs
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return indices
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def op_sharding_to_indices(
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op_sharding: xc.HloSharding, shape: Sequence[int],
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num_devices: int) -> Tuple[Tuple[slice, ...], ...]:
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indices = op_sharding_to_numpy_indices(op_sharding, shape, num_devices)
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return tuple(indices.flat)
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