[HybridParallel]Support finetinue model for PipelineParallel (#35287)

* add cache for send_recv

* add eval_batch for pipeline

* add eval batch for pipelineparallel

* add style code

paddle/fluid/framework/distributed_strategy.proto

@@ -158,6 +158,7 @@ message PipelineConfig {
   optional int32 micro_batch_size = 1 [ default = 1 ];
   optional int32 accumulate_steps = 2 [ default = 1 ];
   optional string schedule_mode = 3 [ default = '1F1B' ];
+  optional bool p2p_cache_shape = 4 [ default = true ];
 }
 
 message TensorParallelConfig {

python/paddle/distributed/fleet/meta_parallel/pipeline_parallel.py

@@ -42,11 +42,13 @@ class PipelineParallel(MetaParallelBase):
         self.accumulate_steps = self._strategy.pipeline_configs[
             'accumulate_steps']
 
+        self._using_cache = self._strategy.pipeline_configs['p2p_cache_shape']
+
         self.num_stages = self._hcg.get_pipe_parallel_world_size()
         self.stage_id = self._hcg.get_stage_id()
         self.pp_group = self._hcg.get_pipe_parallel_group()
 
-        p2p.initialize_p2p_groups(hcg)
+        p2p.initialize_p2p_groups(hcg, self._using_cache)
 
         _initialize_recompute_hcg(hcg)
 
@@ -55,6 +57,8 @@ class PipelineParallel(MetaParallelBase):
         self.global_rank = self._hcg.get_global_rank()
         self.micro_batch_id = 0
 
+        self._compute_loss = True
+
         logger.info("Pipeline Info -- num_stages: {}, stage_id: {}".format(
             self.num_stages, self.stage_id))
 
@@ -85,6 +89,7 @@ class PipelineParallel(MetaParallelBase):
         self.lr_scheduler = lr_scheduler
         self.scaler = scaler
         self.data = data
+        self._compute_loss = True
 
         self._layers.train()
 
@@ -151,12 +156,57 @@ class PipelineParallel(MetaParallelBase):
 
         self._layers.allreduce_shared_weight_gradients()
 
-        self.train_loss = self._reduce_final_loss()
+        self.train_loss = self._broadcast_final_loss()
 
         # optimizer
         self._optimizer_step()
         return self.train_loss
 
+    def eval_batch(self, data, compute_loss=False):
+        self._layers.eval()
+        self._compute_loss = compute_loss
+
+        # save data for eval
+        self.data = data
+        # store data id for micro_batch
+        self.micro_batch_id = 0
+
+        # store total loss of entire batch
+        self.total_loss = None
+
+        startup_steps = (self.num_stages - self.stage_id - 1)
+        startup_steps = min(startup_steps, self.accumulate_steps)
+        steady_steps = self.accumulate_steps - startup_steps
+
+        input_buffers = []
+        output_buffers = []
+
+        for step_id in range(startup_steps):
+            input_tensor = p2p.recv_forward()
+
+            output_tensor = self._forward_step(input_tensor)
+            p2p.send_forward(output_tensor)
+
+            input_buffers.append(input_tensor)
+            output_buffers.append(output_tensor)
+
+        if steady_steps > 0:
+            input_tensor = p2p.recv_forward()
+
+        for i in range(steady_steps):
+            last_iter = (i == (steady_steps - 1))
+
+            output_tensor = self._forward_step(input_tensor)
+            p2p.send_forward(output_tensor)
+
+            input_buffers.append(input_tensor)
+            output_buffers.append(output_tensor)
+
+            if not last_iter:
+                input_tensor = p2p.recv_forward()
+
+        return self.total_loss if self._compute_loss else output_buffers
+
     def _forward_step(self, input_tensor):
         if self.stage_id == 0:
             input_tensor = self._load_micro_batch(self.micro_batch_id)
@@ -164,11 +214,14 @@ class PipelineParallel(MetaParallelBase):
         output_tensor = self._layers.forward(input_tensor)
 
         if self.is_last_stage:
+            # train calculate loss for train
+            if self._compute_loss:
+                assert self._layers._loss_fn is not None, "loss function should exist to compute loss"
                 labels = self._load_micro_batch(self.micro_batch_id)
                 output_tensor = self._layers._loss_fn(output_tensor, labels)
                 assert isinstance(
-                output_tensor, paddle.
-                Tensor), "Currently, loss_fn should obtain Paddle.Tensor dtype"
+                    output_tensor, paddle.Tensor
+                ), "Currently, loss_fn should obtain Paddle.Tensor dtype"
 
                 if self.accumulate_steps > 1:
                     output_tensor = output_tensor / self.accumulate_steps
@@ -245,7 +298,7 @@ class PipelineParallel(MetaParallelBase):
             # No data input is required for other stages
             inputs = None
 
-    def _reduce_final_loss(self):
+    def _broadcast_final_loss(self):
         if self.is_last_stage:
             assert self.total_loss is not None, "train_batch() in last stage should obtain vaild loss"
             loss = self.total_loss.detach()

python/paddle/distributed/fleet/meta_parallel/pp_utils/p2p_communication.py

@@ -19,11 +19,13 @@ import numpy as np
 from paddle import _C_ops
 
 _hcg = None
+_use_cache = False
 
 
-def initialize_p2p_groups(hcg):
-    global _hcg
+def initialize_p2p_groups(hcg, use_cache=True):
+    global _hcg, _use_cache
     _hcg = hcg
+    _use_cache = use_cache
     send_next_group, send_prev_group, recv_next_group, recv_prev_group = _hcg.get_p2p_groups(
     )
 
@@ -372,7 +374,7 @@ def recv_forward():
     else:
         if not _send_recv_meta.has_recv_meta:
             _send_recv_meta.recv_meta(_hcg.recv_prev_group)
-            _send_recv_meta.has_recv_meta = True
+            _send_recv_meta.has_recv_meta = _use_cache
 
         input_tensor, _ = _p2p_helper(
             tensor_send_next=None,
@@ -399,7 +401,7 @@ def send_forward(output_tensor):
         if not _send_recv_meta.has_send_meta:
             _send_recv_meta.set_send_message(output_tensor)
             _send_recv_meta.send_meta(output_tensor, _hcg.send_next_group)
-            _send_recv_meta.has_send_meta = True
+            _send_recv_meta.has_send_meta = _use_cache
 
         _p2p_helper(
             tensor_send_next=output_tensor,

python/paddle/fluid/tests/unittests/hybrid_parallel_pp_transformer.py

@@ -177,10 +177,13 @@ class TestDistPPTraning(unittest.TestCase):
             x_data = np.random.randint(0, vocab_size, size=[batch_size, length])
             x = paddle.to_tensor(x_data)
             x.stop_gradient = True
+
+            e_loss = model.eval_batch([x, x], True)
             loss = model.train_batch([x, x], optimizer, scheduler)
-            # TODO(shenliang03) add utest for loss
 
-            print("loss: ", loss)
+            # TODO(shenliang03) add utest for loss
+            if pp_id != 0:
+                np.testing.assert_allclose(loss.numpy(), e_loss.numpy())
 
 
 if __name__ == "__main__":