dataloader_type argument fix + randomsampler fix

megatron/arguments.py

@@ -124,6 +124,9 @@ def parse_args(extra_args_provider=None, defaults={},
         print('using {} for parameters ...'.format(args.params_dtype),
               flush=True)
 
+    if args.dataloader_type is None:
+        args.dataloader_type = 'single'
+
     # Consumed tokens.
     args.consumed_train_samples = 0
     args.consumed_valid_samples = 0
@@ -365,7 +368,7 @@ def _add_training_args(parser):
     group.add_argument('--optimizer', type=str, default='adam',
                        choices=['adam', 'sgd'],
                        help='Optimizer function')
-    group.add_argument('--dataloader_type', type=str, default='single',
+    group.add_argument('--dataloader-type', type=str, default=None,
                        choices=['single', 'cyclic'],
                        help='Single pass vs multiple pass data loader')
     return parser

megatron/data/data_samplers.py

@@ -105,6 +105,8 @@ class MegatronPretrainingRandomSampler:
         self.data_parallel_size = data_parallel_size
         self.micro_batch_times_data_parallel_size = \
             self.micro_batch_size * data_parallel_size
+        self.last_batch_size = \
+            self.total_samples % self.micro_batch_times_data_parallel_size
 
         # Sanity checks.
         assert self.total_samples > 0, \
@@ -119,8 +121,9 @@ class MegatronPretrainingRandomSampler:
         return self.total_samples
 
     def __iter__(self):
-        self.epoch = self.consumed_samples // self.total_samples
-        current_epoch_samples = self.consumed_samples % self.total_samples
+        active_total_samples = self.total_samples - self.last_batch_size
+        self.epoch = self.consumed_samples // active_total_samples
+        current_epoch_samples = self.consumed_samples % active_total_samples
         assert current_epoch_samples % self.micro_batch_times_data_parallel_size == 0
 
         # data sharding and random sampling
@@ -142,4 +145,3 @@ class MegatronPretrainingRandomSampler:
                 self.consumed_samples += self.micro_batch_times_data_parallel_size
                 yield batch
                 batch = []
-        self.consumed_samples += self.total_samples % self.micro_batch_times_data_parallel_size