Yii : set item per page CGridView

 public function search()  
 {  
     // Warning: Please modify the following code to remove attributes that  
     // should not be searched.  
     $criteria=new CDbCriteria;  
     ...  
     return new CActiveDataProvider('Client', array(  
         'criteria'=>$criteria,  
         'pagination'=>array(  
             'pageSize'=>50,  
         ),  
     ));  
 }