Ah…u are right, @giuseros sorry i mislead u. I remembered wrong before. We will have one default value, it is 1 if i remember correctly. But even we could have one value, the value is not trusted, because we haven’t tuned it. We maybe could say we could fix it for 4 or 8, but I think it doesn’t bring much benefit, because when we enter into fallback, the performance we will not guarantee, if u really want to do it, you could set 4 or 8 like I said when to enter into fallback, but it doesn’t mean much.