On Tue 12-04-16 18:54:43, Waiman Long wrote: > Linked list is used everywhere in the Linux kernel. However, if many > threads are trying to add or delete entries into the same linked list, > it can create a performance bottleneck. > > This patch introduces a new per-cpu list subystem with associated > per-cpu locks for protecting each of the lists individually. This > allows list entries insertion and deletion operations to happen in > parallel instead of being serialized with a global list and lock. > > List entry insertion is strictly per cpu. List deletion, however, can > happen in a cpu other than the one that did the insertion. So we still > need lock to protect the list. Because of that, there may still be > a small amount of contention when deletion is being done. > > A new header file include/linux/percpu-list.h will be added with the > associated pcpu_list_head and pcpu_list_node structures. The following > functions are provided to manage the per-cpu list: > > 1. int init_pcpu_list_head(struct pcpu_list_head **ppcpu_head) > 2. void pcpu_list_add(struct pcpu_list_node *node, > struct pcpu_list_head *head) > 3. void pcpu_list_del(struct pcpu_list *node) > > Iteration of all the list entries within a group of per-cpu > lists is done by calling either the pcpu_list_iterate() or > pcpu_list_iterate_safe() functions in a while loop. They correspond > to the list_for_each_entry() and list_for_each_entry_safe() macros > respectively. The iteration states are keep in a pcpu_list_state > structure that is passed to the iteration functions. > > Signed-off-by: Waiman Long <Waiman.Long@xxxxxxx> The patch looks good to me now. So you can add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
