[Gemini] add some code for reduce-scatter overlap, chunk prefetch in llama benchmark. (#5751)

* [bugs] fix args.profile=False DummyProfiler errro

* add args.prefetch_num for benchmark

examples/language/llama/benchmark.py

@@ -79,7 +79,7 @@ def main():
     parser.add_argument("--custom-ckpt", action="store_true", help="Customize checkpoint", default=False)
     parser.add_argument("--profile", action="store_true", help="Enable profiling", default=False)
     parser.add_argument("--disable-async-reduce", action="store_true", help="Customize checkpoint", default=False)
-
+    parser.add_argument("--prefetch_num", type=int, default=0, help="chunk prefetch max number")
     args = parser.parse_args()
 
     colossalai.launch_from_torch()
@@ -114,7 +114,7 @@ def main():
             extra_dp_size=args.extra_dp,
             enable_fused_normalization=torch.cuda.is_available(),
             enable_flash_attention=args.xformers,
-            max_prefetch=10,
+            max_prefetch=args.prefetch_num,
             enable_async_reduce=not args.disable_async_reduce,
         )
     elif args.plugin == "gemini_auto":
@@ -125,6 +125,8 @@ def main():
             tp_size=args.tp,
             extra_dp_size=args.extra_dp,
             enable_fused_normalization=torch.cuda.is_available(),
+            max_prefetch=args.prefetch_num,
+            enable_async_reduce=not args.disable_async_reduce,
             enable_flash_attention=args.xformers,
         )
     elif args.plugin == "fsdp":

examples/language/performance_evaluator.py

@@ -36,6 +36,12 @@ def get_profile_context(enable_flag, warmup_steps, active_steps, save_dir):
         def step(self):
             self.step_number += 1
 
+        def __enter__(self):
+            return self
+
+        def __exit__(self, exc_type, exc_value, traceback):
+            pass
+
     if enable_flag:
         return profile(
             activities=[ProfilerActivity.CPU, ProfilerActivity.CUDA],