On Wed, Oct 23, 2013 at 09:29:24PM +0800, Xiao Guangrong wrote: > Change the algorithm to: > 1) always add new desc to the first desc (pointed by parent_ptes/rmap) > that is good to implement rcu-nulls-list-like lockless rmap > walking > > 2) always move the entry in the first desc to the the position we want > to remove when delete a spte in the parent_ptes/rmap （backward-move). > It is good for us to implement lockless rmap walk since in the current > code, when a spte is deleted from the "desc", another spte in the last > "desc" will be moved to this position to replace the deleted one. If the > deleted one has been accessed and we do not access the replaced one, the > replaced one is missed when we do lockless walk. > To fix this case, we do not backward move the spte, instead, we forward > move the entry: when a spte is deleted, we move the entry in the first > desc to that position > > Both of these also can reduce cache miss > > Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx> Reviewed-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> -- 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
