Enable megatron core loggers for GPT pretraining (#8354) (#8384)

* Logging changes tested for gpt_pretraining



* Additional args



* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Signed-off-by: Aishwarya Bhandare <[email protected]>
Co-authored-by: ashbhandare <[email protected]>
Co-authored-by: Aishwarya Bhandare <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Eric Harper <[email protected]>

examples/nlp/language_modeling/conf/megatron_gpt_config.yaml

@@ -211,6 +211,13 @@ model:
   ## Network
   sharp: False # Enable the use of SHARP for NCCL data-parallel communications. This is going to be ignored if the network doesn't support SHARP.
 
+  ## Megatron timers
+  enable_megatron_timers: False
+  megatron_timer_kwargs:
+    log_every_n_steps: 10
+    log_mode: minmax
+    barrier: False
+
   data:
    # Path to data must be specified by the user.
     # Supports List, String and Dictionary

examples/nlp/language_modeling/conf/megatron_model_base_config.yaml

@@ -37,4 +37,5 @@ normalize_attention_scores: True # Whether to scale the output Q * K^T by 1 / sq
 num_moe_experts: 1 # When >1, FFNs are changed to MoE layers
 moe_frequency: 1 # every Nth ffn layer will be made MoE 
 moe_dropout: 0.0 # Dropout value for MoE layers
-use_flash_attention: false # Use flash attention in self-attention module
+use_flash_attention: false # Use flash attention in self-attention module
+enable_megatron_timers: false # Megatron timers

nemo/collections/nlp/models/language_modeling/megatron_base_model.py

@@ -69,6 +69,13 @@
 
     HAVE_MEGATRON_CORE = False
 
+try:
+    from megatron.core import Timers
+
+    HAVE_MEGATRON_CORE_TIMERS = True
+except (ImportError, ModuleNotFoundError):
+    HAVE_MEGATRON_CORE_TIMERS = False
+
 __all__ = ["MegatronBaseModel"]
 
 
@@ -124,6 +131,17 @@ def __init__(self, cfg: DictConfig, trainer: Trainer, no_lm_init=True):
             else torch.float32
         )
 
+        self.megatron_timers = None
+        if self.cfg.get('enable_megatron_timers', False) and HAVE_MEGATRON_CORE_TIMERS:
+            self.megatron_timers_cfg = dict(self.cfg.get('megatron_timer_kwargs', dict()))
+            if 'log_every_n_steps' not in self.megatron_timers_cfg:
+                self.megatron_timers_cfg['log_every_n_steps'] = self.trainer.log_every_n_steps
+            if 'log_option' not in self.megatron_timers_cfg:
+                self.megatron_timers_cfg['log_option'] = 'minmax'  # minmax, max, all
+            if 'barrier' not in self.megatron_timers_cfg:
+                self.megatron_timers_cfg['barrier'] = False
+            self.megatron_timers = Timers(log_level=2, log_option=self.megatron_timers_cfg['log_option'])
+
         # set the megatron core model parallel config
         self.model_parallel_config: ModelParallelConfig = self.build_model_parallel_config()
 
@@ -615,6 +633,13 @@ def sync_overlap_parameters(self, params=None):
     def on_train_batch_end(self, outputs, dataloader_iter: Any, batch_idx: int, unused: Optional[int] = 0) -> None:
         super().on_train_batch_end(outputs, dataloader_iter, batch_idx)
 
+        # Megatron Timers
+        if self.megatron_timers:
+            if self.global_step % self.megatron_timers_cfg["log_every_n_steps"] == 0:
+                logging.info(
+                    "\n " + self.megatron_timers.get_all_timers_string(barrier=self.megatron_timers_cfg["barrier"])
+                )
+
         # TODO: Replace with newer override for scheduler.step() instead of
         # search for plugins for fp16 GradScalar
         if self.trainer.precision_plugin is not None and isinstance(
@@ -1044,7 +1069,7 @@ def build_model_parallel_config(self) -> ModelParallelConfig:
             and megatron_amp_O2,  # NeMo does not currently support fp16 training with megatron amp O2, eval and inference is supported
             "bf16": self.torch_dtype == torch.bfloat16 and megatron_amp_O2,
             "params_dtype": self.params_dtype,
-            "timers": None,  # NeMo does not currently support megatron core timers
+            "timers": self.megatron_timers,
             "async_tensor_model_parallel_allreduce": self.cfg.get('tensor_model_parallel_world_size', 1) > 1
             and not self.cfg.get('sequence_parallel', False),
             "pipeline_dtype": pipeline_dtype,
@@ -1157,3 +1182,16 @@ def configure_sharded_model(self):
             # Move the CPU-initialized model (with `use_cpu_initialization=True`) to GPU, which is to avoid
             # out-of-memory carash before sharding. In case of GPU-initialized model, this is no-op.
             self.model = self.model.cuda(torch.cuda.current_device())
+
+    def megatron_timer_start(self, name, log_level):
+        if self.megatron_timers:
+            self.megatron_timers(name, log_level).start(barrier=False)
+
+    def megatron_timer_stop(self, name):
+        if self.megatron_timers:
+            self.megatron_timers(name).stop()
+
+    def optimizer_step(self, *args, **kwargs):
+        self.megatron_timer_start('optimizer', log_level=1)
+        super().optimizer_step(*args, **kwargs)
+        self.megatron_timer_stop('optimizer')

nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py

@@ -654,8 +654,11 @@ def training_step(self, dataloader_iter, batch_idx):
 
         # when using sequence parallelism, the sequence parallel layernorm grads must be all-reduced
         if self.cfg.get('tensor_model_parallel_size', 1) > 1 and self.cfg.get('sequence_parallel', False):
+            self.megatron_timer_start('allreduce_sequence_parallel_gradients', log_level=1)
             self.allreduce_sequence_parallel_gradients()
+            self.megatron_timer_stop('allreduce_sequence_parallel_gradients')
 
+        self.megatron_timer_start('gradient_allreduce', log_level=1)
         if self.use_fsdp:
             # Reduce the gradients omitted from FSDP-sharding
             self.allreduce_fsdp_sharding_omitted_gradients()
@@ -673,12 +676,15 @@ def training_step(self, dataloader_iter, batch_idx):
             # async grad allreduce is not currently implemented for O1/autocasting mixed precision training
             # so we all-reduce gradients after the pipeline
             self.allreduce_gradients()  # @sangkug we think this is causing memory to blow up (hurts perf)
+        self.megatron_timer_stop('gradient_allreduce')
 
         if self.cfg.get('pipeline_model_parallel_size', 1) > 1 and self.cfg.get(
             'share_embeddings_and_output_weights', True
         ):
+            self.megatron_timer_start('allreduce_first_last_embeddings', log_level=1)
             # when using pipeline parallelism the first and last stage must keep embeddings in sync
             self.allreduce_first_last_embeddings()
+            self.megatron_timer_stop('allreduce_first_last_embeddings')
 
         ## logging
         if self.log_train_loss: