torchrec.quant

Torchrec Quantization

Torchrec provides a quantized version of EmbeddingBagCollection for inference. It relies on fbgemm quantized ops. This reduces the size of the model weights and speeds up model execution.

Example

>>> import torch.quantization as quant
>>> import torchrec.quant as trec_quant
>>> import torchrec as trec
>>> qconfig = quant.QConfig(
>>>     activation=quant.PlaceholderObserver,
>>>     weight=quant.PlaceholderObserver.with_args(dtype=torch.qint8),
>>> )
>>> quantized = quant.quantize_dynamic(
>>>     module,
>>>     qconfig_spec={
>>>         trec.EmbeddingBagCollection: qconfig,
>>>     },
>>>     mapping={
>>>         trec.EmbeddingBagCollection: trec_quant.EmbeddingBagCollection,
>>>     },
>>>     inplace=inplace,
>>> )

torchrec.quant.embedding_modules

class torchrec.quant.embedding_modules.EmbeddingBagCollection(table_name_to_quantized_weights: Dict[str, Tuple[Tensor, Tensor]], embedding_configs: List[EmbeddingBagConfig], is_weighted: bool, device: device, output_dtype: dtype = torch.float32)

Bases: EmbeddingBagCollectionInterface

EmbeddingBagCollection represents a collection of pooled embeddings (EmbeddingBags). This EmbeddingBagCollection is quantized for lower precision. It relies on fbgemm quantized ops and provides table batching.

It processes sparse data in the form of KeyedJaggedTensor with values of the form [F X B X L] F: features (keys) B: batch size L: Length of sparse features (jagged)

and outputs a KeyedTensor with values of the form [B * (F * D)] where F: features (keys) D: each feature’s (key’s) embedding dimension B: batch size

Parameters:

• table_name_to_quantized_weights (Dict[str, Tuple[Tensor, Tensor]]) – map of tables to quantized weights

• embedding_configs (List[EmbeddingBagConfig]) – list of embedding tables

• is_weighted – (bool): whether input KeyedJaggedTensor is weighted

• device – (Optional[torch.device]): default compute device

Call Args:

features: KeyedJaggedTensor,

Returns:

KeyedTensor

Example:

table_0 = EmbeddingBagConfig(
    name="t1", embedding_dim=3, num_embeddings=10, feature_names=["f1"]
)
table_1 = EmbeddingBagConfig(
    name="t2", embedding_dim=4, num_embeddings=10, feature_names=["f2"]
)
ebc = EmbeddingBagCollection(tables=[eb1_config, eb2_config])

#        0       1        2  <-- batch
# "f1"   [0,1] None    [2]
# "f2"   [3]    [4]    [5,6,7]
#  ^
# feature
features = KeyedJaggedTensor(
    keys=["f1", "f2"],
    values=torch.tensor([0, 1, 2, 3, 4, 5, 6, 7]),
    offsets=torch.tensor([0, 2, 2, 3, 4, 5, 8]),
)

ebc.qconfig = torch.quantization.QConfig(
    activation=torch.quantization.PlaceholderObserver.with_args(
        dtype=torch.qint8
    ),
    weight=torch.quantization.PlaceholderObserver.with_args(dtype=torch.qint8),
)

qebc = QuantEmbeddingBagCollection.from_float(ebc)
quantized_embeddings = qebc(features)

embedding_bag_configs() → List[EmbeddingBagConfig]

forward(features: KeyedJaggedTensor) → KeyedTensor

Parameters:

features (KeyedJaggedTensor) – KJT of form [F X B X L].

Returns:

KeyedTensor

classmethod from_float(module: EmbeddingBagCollection) → EmbeddingBagCollection

is_weighted() → bool

output_dtype() → dtype

training: bool

class torchrec.quant.embedding_modules.EmbeddingCollection(table_name_to_quantized_weights: Dict[str, Tuple[Tensor, Tensor]], tables: List[EmbeddingConfig], device: device, need_indices: bool = False, output_dtype: dtype = torch.float32)

Bases: EmbeddingCollectionInterface

EmbeddingCollection represents a collection of non-pooled embeddings.

It processes sparse data in the form of KeyedJaggedTensor of the form [F X B X L] where:

• F: features (keys)

• B: batch size

• L: length of sparse features (variable)

and outputs Dict[feature (key), JaggedTensor]. Each JaggedTensor contains values of the form (B * L) X D where:

• B: batch size

• L: length of sparse features (jagged)

• D: each feature’s (key’s) embedding dimension and lengths are of the form L

Parameters:

• tables (List[EmbeddingConfig]) – list of embedding tables.

• device (Optional[torch.device]) – default compute device.

• need_indices (bool) – if we need to pass indices to the final lookup result dict

Example:

e1_config = EmbeddingConfig(
    name="t1", embedding_dim=3, num_embeddings=10, feature_names=["f1"]
)
e2_config = EmbeddingConfig(
    name="t2", embedding_dim=3, num_embeddings=10, feature_names=["f2"]
)

ec = EmbeddingCollection(tables=[e1_config, e2_config])

#     0       1        2  <-- batch
# 0   [0,1] None    [2]
# 1   [3]    [4]    [5,6,7]
# ^
# feature

features = KeyedJaggedTensor.from_offsets_sync(
    keys=["f1", "f2"],
    values=torch.tensor([0, 1, 2, 3, 4, 5, 6, 7]),
    offsets=torch.tensor([0, 2, 2, 3, 4, 5, 8]),
)
feature_embeddings = ec(features)
print(feature_embeddings['f2'].values())
tensor([[-0.2050,  0.5478,  0.6054],
[ 0.7352,  0.3210, -3.0399],
[ 0.1279, -0.1756, -0.4130],
[ 0.7519, -0.4341, -0.0499],
[ 0.9329, -1.0697, -0.8095]], grad_fn=<EmbeddingBackward>)

embedding_configs() → List[EmbeddingConfig]

embedding_dim() → int

embedding_names_by_table() → List[List[str]]

forward(features: KeyedJaggedTensor) → Dict[str, JaggedTensor]

Parameters:

features (KeyedJaggedTensor) – KJT of form [F X B X L].

Returns:

Dict[str, JaggedTensor]

classmethod from_float(module: EmbeddingCollection) → EmbeddingCollection

need_indices() → bool

output_dtype() → dtype

state_dict(destination: Optional[Dict[str, Any]] = None, prefix: str = '', keep_vars: bool = False) → Dict[str, Any]

Returns a dictionary containing references to the whole state of the module.

Both parameters and persistent buffers (e.g. running averages) are included. Keys are corresponding parameter and buffer names. Parameters and buffers set to None are not included.

Note

The returned object is a shallow copy. It contains references to the module’s parameters and buffers.

Warning

Currently state_dict() also accepts positional arguments for destination, prefix and keep_vars in order. However, this is being deprecated and keyword arguments will be enforced in future releases.

Warning

Please avoid the use of argument destination as it is not designed for end-users.

Parameters:

• destination (dict, optional) – If provided, the state of module will be updated into the dict and the same object is returned. Otherwise, an OrderedDict will be created and returned. Default: None.

• prefix (str, optional) – a prefix added to parameter and buffer names to compose the keys in state_dict. Default: ''.

• keep_vars (bool, optional) – by default the Tensor s returned in the state dict are detached from autograd. If it’s set to True, detaching will not be performed. Default: False.

Returns:

a dictionary containing a whole state of the module

Return type:

dict

Example:

>>> # xdoctest: +SKIP("undefined vars")
>>> module.state_dict().keys()
['bias', 'weight']

training: bool

torchrec.quant.embedding_modules.quantize_state_dict(module: Module, table_name_to_quantized_weights: Dict[str, Tuple[Tensor, Tensor]], data_type: DataType) → device

Module contents

Torchrec Quantization

Torchrec provides a quantized version of EmbeddingBagCollection for inference. It relies on fbgemm quantized ops. This reduces the size of the model weights and speeds up model execution.

Example

>>> import torch.quantization as quant
>>> import torchrec.quant as trec_quant
>>> import torchrec as trec
>>> qconfig = quant.QConfig(
>>>     activation=quant.PlaceholderObserver,
>>>     weight=quant.PlaceholderObserver.with_args(dtype=torch.qint8),
>>> )
>>> quantized = quant.quantize_dynamic(
>>>     module,
>>>     qconfig_spec={
>>>         trec.EmbeddingBagCollection: qconfig,
>>>     },
>>>     mapping={
>>>         trec.EmbeddingBagCollection: trec_quant.EmbeddingBagCollection,
>>>     },
>>>     inplace=inplace,
>>> )