[dygraph sharding] Overlap the reduce and the caculation for sharding stage 2. (#46495)

python/paddle/distributed/fleet/meta_parallel/sharding/group_sharded_optimizer_stage2.py

@@ -86,6 +86,11 @@ class GroupShardedOptimizerStage2(Optimizer):
         # Default information
         self._optim = optim
 
+        # sharing stage 2 comm overlap flag
+        self._comm_overlap = False
+        # record the last task used for comm overlap for sharding stage 2
+        self._comm_task = None
+
         assert hasattr(self._optim, "_master_weights"
                        ), "Must use optimizer with _master_weights attribute"
 
@@ -157,6 +162,17 @@ class GroupShardedOptimizerStage2(Optimizer):
                       group=self._group,
                       sync_op=True)
 
+    def _update_task(self, task):
+        if self._comm_overlap:
+            assert task is not None
+        # Only track of the last reduce task.
+        # Since all tasks are on the same stream, only need to wait the last one.
+        # After waiting for the last reduce task, all reduce tasks before have already finished.
+        self._comm_task = task
+
+    def _set_comm_overlap(self, comm_overlap):
+        self._comm_overlap = comm_overlap
+
     def _generate_master_params(self, trainable_params):
         if self.offload:
             for param in trainable_params:
@@ -364,7 +380,8 @@ class GroupShardedOptimizerStage2(Optimizer):
         """
         A wrapper for Optimizer's step function to finish the update operation of the optimizer.
         """
-
+        # This method won't be called directly by opt.step()!
+        # The _redefine_opt_step() in class GroupShardedStage2 will wrap this function.
         if self.offload:
             params_list = [self.offload_params.buffer]
 

python/paddle/distributed/fleet/meta_parallel/sharding/group_sharded_stage2.py

@@ -100,6 +100,9 @@ class GroupShardedStage2(nn.Layer):
         for optim in self._sharding_optimizers:
             self._all_params.extend(list(optim.local_params))
 
+        # sharing stage 2 comm overlap flag
+        self._comm_overlap = False
+
         self._trainable_params = []
         self._grad_reduced = []
         self._trainable_param2rank = {}
@@ -306,6 +309,18 @@ class GroupShardedStage2(nn.Layer):
             for grad_storage in self._grad_storage_list:
                 grad_storage.reset_checked_in()
 
+    def _set_comm_overlap(self, comm_overlap):
+        # Hacky way to not add an extra parameter to the `group_sharded_parallel` funct.
+        # User should use this like:
+        # model, optimizer, scaler = group_sharded_parallel(...)
+        # model._set_comm_overlap(True)
+        self._comm_overlap = comm_overlap
+        if self._comm_overlap:
+            assert len(
+                self._sharding_optimizers
+            ) == 1, "Only support comm overlap strategy for single optimizer"
+        self._sharding_optimizers[0]._set_comm_overlap(comm_overlap)
+
     def _get_reduce_fn(self, index, param, dst_rank):
         """
         There are two ways to reduce gradient.
@@ -337,11 +352,12 @@ class GroupShardedStage2(nn.Layer):
                             del tmp_grad
                             param.clear_gradient(False)
 
-                    # Synchronize the reduce parameter gradient
-                    collective.reduce(tensor=param.grad,
-                                      dst=self._group.ranks[dst_rank],
-                                      group=self._group)
-                    #  TODO (Baibaifan) Asynchronous the reduce parameter gradient
+                    # Synchronize the reduce parameter gradient asynchronize
+                    self._sharding_optimizers[0]._update_task(
+                        collective.reduce(tensor=param.grad,
+                                          dst=self._group.ranks[dst_rank],
+                                          group=self._group,
+                                          sync_op=not self._comm_overlap))
 
                     # Clear the task flow and trigger callback to clear the redundant gradient
                     # self._clear_task_flow()
@@ -385,12 +401,13 @@ class GroupShardedStage2(nn.Layer):
 
                         # Reduce the bucket
                         grad_storage.sent = True
-                        # Synchronize the reduce parameter gradient
-                        collective.reduce(
-                            tensor=grad_storage.buffer,
-                            dst=self._group.ranks[grad_storage.destination],
-                            group=self._group)
-                        #  TODO (Baibaifan) Asynchronous the reduce parameter gradient
+                        # Synchronize the reduce parameter gradient asynchronize
+                        self._sharding_optimizers[0]._update_task(
+                            collective.reduce(
+                                tensor=grad_storage.buffer,
+                                dst=self._group.ranks[grad_storage.destination],
+                                group=self._group,
+                                sync_op=not self._comm_overlap))
 
                         cleanup()
 
@@ -528,6 +545,10 @@ class GroupShardedStage2(nn.Layer):
             opt_step = opt.step
 
             def _opt_step(self):
+                if self._comm_overlap:
+                    # Wait for the last reduce task. This wait must before grad scale function.
+                    assert self._comm_task is not None
+                    self._comm_task.wait()
                 grad_func()
                 opt_step()
 

python/paddle/fluid/tests/unittests/collective/fleet/dygraph_group_sharded_stage2_comm_overlap.py

+# -*- coding: UTF-8 -*-
+
+# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import shutil
+import numpy as np
+import argparse
+import tempfile
+import ast
+import time
+import paddle
+import paddle.fluid as fluid
+from paddle.fluid.dygraph.nn import Linear
+from paddle.distributed import fleet
+from paddle.fluid.dygraph import nn
+from paddle.fluid.framework import _test_eager_guard
+
+from paddle.distributed.fleet.meta_parallel.sharding.group_sharded_optimizer_stage2 import GroupShardedOptimizerStage2
+from paddle.distributed.fleet.meta_parallel.sharding.group_sharded_stage2 import GroupShardedStage2
+
+seed = 2022
+epoch = 2
+linear_size = 1000
+
+np.random.seed(seed)
+paddle.seed(seed)
+
+
+class MLP(fluid.Layer):
+
+    def __init__(self, linear_size=1000, param_attr=None, bias_attr=None):
+        super(MLP, self).__init__()
+
+        self._linear1 = Linear(linear_size, linear_size)
+        self._linear2 = Linear(linear_size, linear_size)
+        self._linear3 = Linear(linear_size, 10)
+
+    def forward(self, inputs):
+        y = self._linear1(inputs)
+        y = self._linear2(y)
+        y = self._linear3(y)
+        return y
+
+
+def reader_decorator(linear_size=1000):
+
+    def __reader__():
+        for _ in range(100):
+            img = np.random.rand(linear_size).astype('float32')
+            label = np.ones(1).astype('int64')
+            yield img, label
+
+    return __reader__
+
+
+def optimizer_setting(model, use_pure_fp16, opt_group=False):
+    clip = paddle.nn.ClipGradByGlobalNorm(clip_norm=1.0)
+    optimizer = paddle.optimizer.AdamW(parameters=[{
+        "params": model.parameters(),
+    }] if opt_group else model.parameters(),
+                                       learning_rate=0.001,
+                                       weight_decay=0.00001,
+                                       grad_clip=clip,
+                                       multi_precision=use_pure_fp16)
+
+    return optimizer
+
+
+def train_mlp(model,
+              sharding_stage,
+              batch_size=100,
+              use_pure_fp16=False,
+              accumulate_grad=False,
+              opt_group=False,
+              save_model=False,
+              test_minimize=False):
+    if sharding_stage != "dp":
+        group = paddle.distributed.new_group([0, 1], backend="nccl")
+    if opt_group:
+        optimizer = optimizer_setting(model=model,
+                                      use_pure_fp16=use_pure_fp16,
+                                      opt_group=opt_group)
+    else:
+        optimizer = optimizer_setting(model=model, use_pure_fp16=use_pure_fp16)
+
+    if sharding_stage == 2:
+        optimizer = GroupShardedOptimizerStage2(
+            params=optimizer._parameter_list, optim=optimizer, group=group)
+        model = GroupShardedStage2(model,
+                                   optimizer,
+                                   group=group,
+                                   buffer_max_size=2**21)
+        model._set_comm_overlap(True)
+    else:
+        model = paddle.DataParallel(model)
+
+    # check optimizer.minimize() error
+    if test_minimize:
+        try:
+            optimizer.minimize()
+        except:
+            print(
+                "====== Find sharding_stage2_optimizer.minimize() error ======")
+        return
+
+    train_reader = paddle.batch(reader_decorator(),
+                                batch_size=batch_size,
+                                drop_last=True)
+
+    train_loader = paddle.io.DataLoader.from_generator(capacity=32,
+                                                       use_double_buffer=True,
+                                                       iterable=True,
+                                                       return_list=True,
+                                                       use_multiprocess=True)
+    train_loader.set_sample_list_generator(train_reader)
+
+    if sharding_stage == 2:
+        model.to(device="gpu")
+
+    for eop in range(epoch):
+        model.train()
+
+        for batch_id, data in enumerate(train_loader()):
+            img, label = data
+            label.stop_gradient = True
+            img.stop_gradient = True
+
+            out = model(img)
+            loss = paddle.nn.functional.cross_entropy(input=out, label=label)
+
+            avg_loss = paddle.mean(x=loss.cast(dtype=paddle.float32))
+            if batch_size == 20:
+                avg_loss = avg_loss / 5
+            avg_loss.backward()
+
+            if not accumulate_grad:
+                optimizer.step()
+                optimizer.clear_grad()
+
+        if accumulate_grad:
+            optimizer.step()
+            optimizer.clear_grad()
+
+    if save_model:
+        return model, optimizer
+    return model.parameters()
+
+
+def test_dp_stage2():
+    paddle.distributed.init_parallel_env()
+    mlp = MLP()
+    state_dict = mlp.state_dict()
+    mlp1 = MLP()
+    mlp2 = MLP()
+    mlp3 = MLP()
+    mlp4 = MLP()
+    mlp5 = MLP()
+    mlp6 = MLP()
+    mlp7 = MLP()
+    mlp1.set_state_dict(state_dict)
+    mlp2.set_state_dict(state_dict)
+    mlp3.set_state_dict(state_dict)
+    mlp4.set_state_dict(state_dict)
+    mlp5.set_state_dict(state_dict)
+    mlp6.set_state_dict(state_dict)
+    mlp7.set_state_dict(state_dict)
+
+    # DP VS stage2
+    dp_params = train_mlp(mlp1,
+                          sharding_stage="dp",
+                          use_pure_fp16=False,
+                          opt_group=False)
+    stage2_params = train_mlp(mlp2,
+                              sharding_stage=2,
+                              use_pure_fp16=False,
+                              opt_group=False)
+    for i in range(len(dp_params)):
+        np.testing.assert_allclose(dp_params[i].numpy(),
+                                   stage2_params[i].numpy(),
+                                   rtol=1e-6)
+
+    # stage2 accumulate grad
+    stage2_params = train_mlp(mlp3, sharding_stage=2, accumulate_grad=True)
+    stage2_accumulate_grad = train_mlp(mlp4,
+                                       sharding_stage=2,
+                                       batch_size=20,
+                                       accumulate_grad=True)
+    for i in range(len(stage2_params)):
+        np.testing.assert_allclose(stage2_params[i].numpy(),
+                                   stage2_accumulate_grad[i].numpy(),
+                                   rtol=1e-5,
+                                   atol=1e-5)
+
+    # stage2 param list VS param group
+    stage2_params = train_mlp(mlp5,
+                              sharding_stage=2,
+                              use_pure_fp16=False,
+                              opt_group=True)
+    for i in range(len(dp_params)):
+        np.testing.assert_allclose(dp_params[i].numpy(),
+                                   stage2_params[i].numpy(),
+                                   rtol=1e-6)
+
+    # save/load model
+    output_dir = tempfile.mkdtemp()
+    model_file = os.path.join(output_dir, "model.pdmodel")
+    optimizer_file = os.path.join(output_dir, "model.pdopt")
+    model_stage2, optimizer_stage2 = train_mlp(mlp6,
+                                               sharding_stage=2,
+                                               use_pure_fp16=False,
+                                               opt_group=False,
+                                               save_model=True)
+    paddle.save(model_stage2.state_dict(), model_file)
+    paddle.save(optimizer_stage2.state_dict(), optimizer_file)
+    m_state_dict = paddle.load(model_file)
+    opt_state_dict = paddle.load(optimizer_file)
+    model_stage2.set_state_dict(m_state_dict)
+    optimizer_stage2.set_state_dict(opt_state_dict)
+    shutil.rmtree(output_dir)
+
+    # check optimizer.minimize() error
+    train_mlp(mlp7, sharding_stage=2, test_minimize=True)
+    return
+
+
+if __name__ == '__main__':
+    with _test_eager_guard():
+        test_dp_stage2()

python/paddle/fluid/tests/unittests/collective/fleet/test_dygraph_sharding_stage2.py

@@ -31,6 +31,9 @@ class TestDygraphShardingStage2(TestMultipleGpus):
         self.run_mnist_2gpu('dygraph_sharding_stage2_offload.py',
                             eager_mode=False)
 
+    def test_dygraph_sharding_stage2_with_comm_overlap(self):
+        self.run_mnist_2gpu('dygraph_group_sharded_stage2_comm_overlap.py')
+
 
 if __name__ == "__main__":
     os.environ["FLAGS_enable_eager_mode"] = "1"