fixed jit default setting (#154)

colossalai/kernel/jit/__init__.py

-from .option import _set_jit_fusion_options
+from .option import set_jit_fusion_options
 from .bias_dropout_add import bias_dropout_add_fused_train, bias_dropout_add_fused_inference
 from .bias_gelu import bias_gelu_impl
-_set_jit_fusion_options()
 
 __all__ = [
     "bias_dropout_add_fused_train", "bias_dropout_add_fused_inference", "bias_gelu_impl",
+    "set_jit_fusion_options"
 ]

colossalai/kernel/jit/option.py

@@ -3,8 +3,11 @@ import torch
 JIT_OPTIONS_SET = False
 
 
-def _set_jit_fusion_options():
-    """Set PyTorch JIT layer fusion options."""
+def set_jit_fusion_options():
+    """Set PyTorch JIT layer fusion options.
+    """
+    # LSG: the latest pytorch and CUDA versions may not support 
+    # the following jit settings
     global JIT_OPTIONS_SET
     if JIT_OPTIONS_SET == False:
         # flags required to enable jit fusion kernels