(11/1/13 4:17 PM), Davidlohr Bueso wrote:
While caching the last used vma already does a nice job avoiding having to iterate the rbtree in find_vma, we can improve. After studying the hit rate on a load of workloads and environments, it was seen that it was around 45-50% - constant for a standard desktop system (gnome3 + evolution + firefox + a few xterms), and multiple java related workloads (including Hadoop/terasort), and aim7, which indicates it's better than the 35% value documented in the code. By also caching the largest vma, that is, the one that contains most addresses, there is a steady 10-15% hit rate gain, putting it above the 60% region. This improvement comes at a very low overhead for a miss. Furthermore, systems with !CONFIG_MMU keep the current logic.
I'm slightly surprised this cache makes 15% hit. Which application get a benefit? You listed a lot of applications, but I'm not sure which is highly depending on largest vma. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>