Update optimize_model=True in llama2 chatglm2 arc examples (#8878)

* add optimize_model=True in llama2 chatglm2 examples

* add ipex optimize in gpt-j example

python/llm/example/gpu/chatglm2/generate.py

@@ -44,7 +44,7 @@ if __name__ == '__main__':
     # which convert the relevant layers in the model into INT4 format
     model = AutoModel.from_pretrained(model_path,
                                       load_in_4bit=True,
-                                      optimize_model=False,
+                                      optimize_model=True,
                                       trust_remote_code=True)
     model = model.to('xpu')
 

python/llm/example/gpu/gpt-j/generate.py

@@ -45,6 +45,7 @@ if __name__ == '__main__':
                                                  optimize_model=False,
                                                  trust_remote_code=True)
     model = model.to('xpu')
+    model = ipex.optimize(model.eval(), dtype="float16", inplace=True)
 
     # Load tokenizer
     tokenizer = AutoTokenizer.from_pretrained(model_path,

python/llm/example/gpu/llama2/generate.py

@@ -57,7 +57,7 @@ if __name__ == '__main__':
     # which convert the relevant layers in the model into INT4 format
     model = AutoModelForCausalLM.from_pretrained(model_path,
                                                  load_in_4bit=True,
-                                                 optimize_model=False,
+                                                 optimize_model=True,
                                                  trust_remote_code=True)
     model = model.to('xpu')