[zero] polish low level optimizer (#2473)

hpcaitech · Jan 13, 2023 · a5dc425 · a5dc425
1 parent 8b7495d
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Showing 7 changed files with 95 additions and 124 deletions.
diff --git a/colossalai/zero/sharded_optim/_utils.py b/colossalai/zero/sharded_optim/_utils.py
@@ -103,7 +103,11 @@ def split_half_float_double(tensor_list):
     return buckets
 
 
-def reduce_tensor_dp_group(tensor, dtype=None, dst_rank=None, pg: Optional[ProcessGroup] = None):
+def reduce_tensor_dp_group(tensor: torch.Tensor,
+                           dtype: Optional[torch.dtype] = None,
+                           dst_local_rank: Optional[int] = None,
+                           dst_global_rank: Optional[int] = None,
+                           group: Optional[dist.ProcessGroup] = None):
     """
     Reduce the tensor in the data parallel process group
 
@@ -128,36 +132,22 @@ def reduce_tensor_dp_group(tensor, dtype=None, dst_rank=None, pg: Optional[Proce
     else:
         tensor_to_reduce = tensor
 
-    if isinstance(pg, ProcessGroup):
-        group = pg.dp_process_group()
-        world_size = pg.dp_world_size()
-    else:
-        world_size = gpc.get_world_size(ParallelMode.DATA)
-        group = gpc.get_group(ParallelMode.DATA)
-
+    world_size = dist.get_world_size(group=group)
     tensor_to_reduce.div_(world_size)
 
     # if rank is None, all reduce will be used
     # else, reduce is used
-    use_all_reduce = dst_rank is None
+    use_all_reduce = dst_local_rank is None
 
     if use_all_reduce:
         dist.all_reduce(tensor_to_reduce, group=group)
     else:
-        if pg is not None:
-            ranks_in_group = pg.dp_rank_list()
-        else:
-            ranks_in_group = gpc.get_ranks_in_group(ParallelMode.DATA)
-        global_rank = ranks_in_group[dst_rank]
-        dist.reduce(tensor=tensor_to_reduce, dst=global_rank, group=group)
+        dist.reduce(tensor=tensor_to_reduce, dst=dst_global_rank, group=group)
 
     # recover the original dtype
     if tensor.dtype != dtype and tensor is not tensor_to_reduce:
-        if pg is not None:
-            local_rank = pg.dp_local_rank()
-        else:
-            local_rank = gpc.get_local_rank(ParallelMode.DATA)
-        if use_all_reduce or dst_rank == local_rank:
+        local_rank = dist.get_rank(group=group)
+        if use_all_reduce or dst_local_rank == local_rank:
             tensor.copy_(tensor_to_reduce)
 
     return tensor

diff --git a/colossalai/zero/sharded_optim/bookkeeping/base_store.py b/colossalai/zero/sharded_optim/bookkeeping/base_store.py
@@ -1,19 +1,12 @@
-from typing import Optional
-
-from colossalai.context import ParallelMode
-from colossalai.core import global_context as gpc
-from colossalai.tensor import ProcessGroup
+import torch.distributed as dist
+from torch.distributed import ProcessGroup
 
 
 class BaseStore:
 
-    def __init__(self, pg: Optional[ProcessGroup] = None):
-        if isinstance(pg, ProcessGroup):
-            self._world_size = pg.dp_world_size()
-            self._local_rank = pg.dp_local_rank()
-        else:
-            self._world_size = gpc.get_world_size(ParallelMode.DATA)
-            self._local_rank = gpc.get_local_rank(ParallelMode.DATA)
+    def __init__(self, torch_pg: ProcessGroup):
+        self._world_size = dist.get_world_size(group=torch_pg)
+        self._local_rank = dist.get_rank(group=torch_pg)
 
     @property
     def world_size(self):

diff --git a/colossalai/zero/sharded_optim/bookkeeping/bucket_store.py b/colossalai/zero/sharded_optim/bookkeeping/bucket_store.py
@@ -1,14 +1,12 @@
-from typing import Optional
-
-from colossalai.tensor import ProcessGroup
+from torch.distributed import ProcessGroup
 
 from .base_store import BaseStore
 
 
 class BucketStore(BaseStore):
 
-    def __init__(self, pg: Optional[ProcessGroup] = None):
-        super().__init__(pg)
+    def __init__(self, torch_pg: ProcessGroup):
+        super().__init__(torch_pg)
         self._grads = dict()
         self._params = dict()
         self._num_elements_in_bucket = dict()

diff --git a/colossalai/zero/sharded_optim/bookkeeping/parameter_store.py b/colossalai/zero/sharded_optim/bookkeeping/parameter_store.py
@@ -1,16 +1,15 @@
-from typing import List, Optional
+from typing import List
 
 from torch import Tensor
-
-from colossalai.tensor import ProcessGroup
+from torch.distributed import ProcessGroup
 
 from .base_store import BaseStore
 
 
 class ParameterStore(BaseStore):
 
-    def __init__(self, pg: Optional[ProcessGroup] = None):
-        super().__init__(pg)
+    def __init__(self, torch_pg: ProcessGroup):
+        super().__init__(torch_pg)
         # param partitioning data structures
         self._fp16_param_to_rank = dict()
         self._rank_groupid_to_fp16_param_list = dict()

diff --git a/colossalai/zero/sharded_optim/low_level_optim.py b/colossalai/zero/sharded_optim/low_level_optim.py
@@ -10,7 +10,7 @@
 from colossalai.core import global_context as gpc
 from colossalai.logging import get_dist_logger
 from colossalai.nn.optimizer import ColossalaiOptimizer
-from colossalai.tensor import ProcessGroup
+from colossalai.tensor import ColoParameter, ProcessGroup
 from colossalai.utils.cuda import get_current_device
 
 from ._utils import (
@@ -34,32 +34,21 @@ class LowLevelZeroOptimizer(ColossalaiOptimizer):
     def __init__(
             self,
             optimizer: Optimizer,
-            pg: Optional[ProcessGroup] = None,
-    # grad scaler config
-            initial_scale=2**16,
-            min_scale=1,
-            growth_factor=2,
-            backoff_factor=0.5,
-            growth_interval=2000,
-            hysteresis=2,
+            initial_scale: int = 2**16,    # grad scaler config
+            min_scale: int = 1,
+            growth_factor: float = 2.,
+            backoff_factor: float = .5,
+            growth_interval: int = 2000,
+            hysteresis: int = 2,
             max_scale: int = 2**24,
-
-    # grad clipping
-            clip_grad_norm=0.0,
-            verbose=False,
-
-    # communication
-            reduce_bucket_size=1024 * 1024,
-            communication_dtype=None,
-            overlap_communication=False,
-
-    # stage 2
-            partition_grad=False,
-    # cpu offload
-            cpu_offload=False,
-
-    # forced dtype
-            forced_dtype=None):
+            clip_grad_norm: float = 0.0,    # grad clipping
+            verbose: bool = False,
+            reduce_bucket_size: int = 1024 * 1024,    # communication
+            communication_dtype: Optional[torch.dtype] = None,
+            overlap_communication: bool = False,
+            partition_grad: bool = False,    # stage 2
+            cpu_offload: bool = False,    # cpu offload
+            forced_dtype: Optional[torch.dtype] = None):
 
         # TODO: add support for
         # 1. fp16 master weights
@@ -76,31 +65,30 @@ def __init__(
 
         self._cpu_offload = cpu_offload
 
-        self._pg = pg
-        if isinstance(pg, ProcessGroup):
-            self._local_rank = pg.dp_local_rank()
-            self._world_size = pg.dp_world_size()
-            self._dp_group = pg.dp_process_group()
-            if pg.tp_world_size() > 1:
-                self._mp_group = pg.tp_process_group()
-            else:
-                self._mp_group = None
-        elif pg is None:
+        colo_pg = self._search_colo_process_group()
+        if isinstance(colo_pg, ProcessGroup):
+            self._local_rank = colo_pg.dp_local_rank()
+            self._world_size = colo_pg.dp_world_size()
+            self._dp_global_ranks = colo_pg.get_ranks_in_dp()
+            self._dp_torch_group = colo_pg.dp_process_group()
+            self._mp_torch_group = None
+            if colo_pg.tp_world_size() > 1:
+                self._mp_torch_group = colo_pg.tp_process_group()
+        elif colo_pg is None:
             dp_parallel_mode = ParallelMode.DATA
             mp_parallel_mode = ParallelMode.MODEL
 
             self._dp_parallel_mode = dp_parallel_mode
             self._mp_parallel_mode = mp_parallel_mode
             self._local_rank = gpc.get_local_rank(dp_parallel_mode)
             self._world_size = gpc.get_world_size(dp_parallel_mode)
-
-            self._dp_group = gpc.get_group(dp_parallel_mode)
+            self._dp_global_ranks = gpc.get_ranks_in_group(dp_parallel_mode)
+            self._dp_torch_group = gpc.get_group(dp_parallel_mode)
+            self._mp_torch_group = None
             if gpc.is_initialized(mp_parallel_mode) and gpc.get_world_size(mp_parallel_mode) > 1:
-                self._mp_group = gpc.get_group(mp_parallel_mode)
-            else:
-                self._mp_group = None
+                self._mp_torch_group = gpc.get_group(mp_parallel_mode)
         else:
-            raise TypeError(f"pg should be None or a ProcesGroup")
+            raise NotImplementedError
         # fp16 and fp32 params for mixed precision training
         self._fp16_param_groups = dict()
         self._fp32_flat_param_groups_of_current_rank = dict()
@@ -136,14 +124,9 @@ def __init__(
 
         # ParameterStore will manage the tensor buffers used for zero
         # it will not manage the tensors used by mixed precision training
-        if self._pg is not None:
-            self._param_store = ParameterStore(self._pg)
-            self._grad_store = GradientStore(self._pg)
-            self._bucket_store = BucketStore(self._pg)
-        else:
-            self._param_store = ParameterStore(self._dp_parallel_mode)
-            self._grad_store = GradientStore(self._dp_parallel_mode)
-            self._bucket_store = BucketStore(self._dp_parallel_mode)
+        self._param_store = ParameterStore(self._dp_torch_group)
+        self._grad_store = GradientStore(self._dp_torch_group)
+        self._bucket_store = BucketStore(self._dp_torch_group)
 
         # iterate over the param group in the optimizer
         # partition these param groups for data parallel training
@@ -224,6 +207,30 @@ def loss_scale(self):
     def num_param_groups(self):
         return len(self._fp16_param_groups)
 
+    def _sanity_checks(self):
+        assert torch.cuda.is_available(), 'CUDA is required'
+        for param_group in self.optim.param_groups:
+            group_params = param_group['params']
+            for param in group_params:
+                assert param.dtype == self._dtype, \
+                    f"Parameters are expected to have the same dtype `{self._dtype}`, but got `{param.dtype}`"
+
+    def _search_colo_process_group(self):
+        colo_flag = False
+        colo_pg = None
+        for param_group in self.optim.param_groups:
+            group_params = param_group['params']
+            for param in group_params:
+                if isinstance(param, ColoParameter):
+                    colo_flag = True
+                    if colo_pg is None:
+                        colo_pg = param.get_process_group()
+                    else:
+                        assert colo_pg == param.get_process_group(), "All parameters should be in a same process group"
+                elif colo_flag:
+                    raise RuntimeError("All parameters should be ColoParameter if you use ColoParameter.")
+        return colo_pg
+
     def _partition_param_list(self, param_list):
         params_per_rank = [[] for _ in range(self._world_size)]
         numel_per_rank = [0 for _ in range(self._world_size)]
@@ -241,14 +248,6 @@ def _partition_param_list(self, param_list):
             self._logger.info(f'Number of elements on ranks: {numel_per_rank}', ranks=[0])
         return params_per_rank
 
-    def _sanity_checks(self):
-        assert torch.cuda.is_available(), 'CUDA is required'
-        for param_group in self.optim.param_groups:
-            group_params = param_group['params']
-            for param in group_params:
-                assert param.dtype == self._dtype, \
-                    f"Parameters are expected to have the same dtype `{self._dtype}`, but got `{param.dtype}`"
-
     ###########################################################
     # Backward Reduction Hook
     ###########################################################
@@ -384,10 +383,14 @@ def _reduce_and_copy(self, bucket: TensorBucket, reduce_rank):
 
         with torch.cuda.stream(stream):
             flat = bucket.flatten()
+            reduce_global_rank = None
+            if reduce_rank is not None:
+                reduce_global_rank = self._dp_global_ranks[reduce_rank]
             reduced_flat = reduce_tensor_dp_group(tensor=flat,
                                                   dtype=self._communication_dtype,
-                                                  dst_rank=reduce_rank,
-                                                  pg=self._pg)
+                                                  dst_local_rank=reduce_rank,
+                                                  dst_global_rank=reduce_global_rank,
+                                                  group=self._dp_torch_group)
 
             # update the reduced tensor
             if reduce_rank is None or reduce_rank == self._local_rank:
@@ -456,8 +459,8 @@ def step(self, closure=None):
             norm_group = compute_norm(gradients=self._grad_store._averaged_gradients[group_id],
                                       params=self._param_store.get_fp16_params_by_rank_group(group_id=group_id,
                                                                                              rank=self._local_rank),
-                                      dp_group=self._dp_group,
-                                      mp_group=self._mp_group)
+                                      dp_group=self._dp_torch_group,
+                                      mp_group=self._mp_torch_group)
             norm_groups.append(norm_group)
 
             # create flat gradient for the flat fp32 params
@@ -497,7 +500,7 @@ def step(self, closure=None):
         for group_id in range(self.num_param_groups):
             for rank in range(self._world_size):
                 fp16_param = self._param_store.get_flat_fp16_param_by_rank_group(rank=rank, group_id=group_id)
-                handle = dist.broadcast(fp16_param, src=rank, group=self._dp_group, async_op=True)
+                handle = dist.broadcast(fp16_param, src=rank, group=self._dp_torch_group, async_op=True)
                 handles.append(handle)
 
         for handle in handles:
@@ -519,11 +522,11 @@ def _check_overflow(self):
                     break
 
         # all-reduce across dp group
-        dist.all_reduce(self._found_overflow, op=dist.ReduceOp.MAX, group=self._dp_group)
+        dist.all_reduce(self._found_overflow, op=dist.ReduceOp.MAX, group=self._dp_torch_group)
 
         # all-reduce over model parallel group
-        if self._mp_group:
-            dist.all_reduce(self._found_overflow, op=dist.ReduceOp.MAX, group=self._mp_group)
+        if self._mp_torch_group:
+            dist.all_reduce(self._found_overflow, op=dist.ReduceOp.MAX, group=self._mp_torch_group)
 
         if self._found_overflow.item() > 0:
             return True

diff --git a/tests/test_zero/low_level_zero/test_grad_acc.py b/tests/test_zero/low_level_zero/test_grad_acc.py
@@ -35,18 +35,15 @@ def exam_zero_1_2_grad_acc():
     # create model
     zero1_model = TestModel().cuda()
     zero2_model = copy.deepcopy(zero1_model)
-    pg = ProcessGroup()
     # create optimizer
     zero1_optimizer = torch.optim.Adam(zero1_model.parameters(), lr=1)
     zero2_optimizer = torch.optim.Adam(zero2_model.parameters(), lr=1)
     zero1_optimizer = LowLevelZeroOptimizer(zero1_optimizer,
-                                            pg=pg,
                                             overlap_communication=True,
                                             initial_scale=32,
                                             clip_grad_norm=1.0,
                                             verbose=True)
     zero2_optimizer = LowLevelZeroOptimizer(zero2_optimizer,
-                                            pg=pg,
                                             overlap_communication=True,
                                             partition_grad=True,
                                             initial_scale=32,
@@ -86,7 +83,7 @@ def fwd_bwd_func(number, cur_data):
         assert torch.equal(z1p.data, z2p.data)
 
 
-def exam_zero_1_grad_acc(use_pg=True):
+def exam_zero_1_grad_acc():
     local_rank = torch.distributed.get_rank()
     grad_scale = 32
     seed_all(2008)
@@ -105,9 +102,7 @@ def exam_zero_1_grad_acc(use_pg=True):
     # we only test stage 1 here
     # in `check_sharded_param_consistency.py`, we will test whether
     # level 1 and 2 will produce exactly the same results
-    pg = ProcessGroup() if use_pg else None    #ProcessGroup()
     zero_optimizer = LowLevelZeroOptimizer(zero_optimizer,
-                                           pg=pg,
                                            overlap_communication=False,
                                            initial_scale=grad_scale,
                                            reduce_bucket_size=262144,
@@ -158,9 +153,8 @@ def fwd_bwd_func(number, cur_data, check_flag):
 def run_dist(rank, world_size, port):
     colossalai.launch(config=dict(), rank=rank, world_size=world_size, port=port, host='localhost')
 
-    exam_zero_1_grad_acc(True)
-    exam_zero_1_grad_acc(False)
-    # exam_zero_1_2_grad_acc()
+    exam_zero_1_grad_acc()
+    exam_zero_1_2_grad_acc()
 
 
 @pytest.mark.dist