Hello Avi, On Sun, 2010-08-01 at 11:18 +0300, Avi Kivity wrote: > I don't understand. Under what conditions do you use > get_user_pages() > instead of get_user_pages_fast()? Why? The code always calls get_user_pages_fast, however, the page will be unpinned in skb_free if the same page is not used again for a new buffer. The reason for unpin the page is we don't want to pin all of the guest kernel memory(memory over commit). So get_user_pages_fast will call slow path get_user_pages. Your previous comment is suggesting to keep the page pinned for get_user_pages_fast fast path? Thanks Shirley -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html