On Thu 05-10-17 14:43:26, Waiman Long wrote:
> The dlock list needs one list for each of the CPUs available. However,
> for sibling CPUs, they are sharing the L2 and probably L1 caches
> too. As a result, there is not much to gain in term of avoiding
> cacheline contention while increasing the cacheline footprint of the
> L1/L2 caches as separate lists may need to be in the cache.
>
> This patch makes all the sibling CPUs share the same list, thus
> reducing the number of lists that need to be maintained in each
> dlock list without having any noticeable impact on performance. It
> also improves dlock list iteration performance as fewer lists need
> to be iterated.
>
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
...
> @@ -118,7 +156,7 @@ bool dlock_lists_empty(struct dlock_list_heads *dlist)
> {
> int idx;
>
> - for (idx = 0; idx < nr_cpu_ids; idx++)
> + for (idx = 0; idx < nr_dlock_lists; idx++)
> if (!list_empty(&dlist->heads[idx].list))
> return false;
> return true;
> @@ -207,7 +245,7 @@ struct dlock_list_node *__dlock_list_next_list(struct dlock_list_iter *iter)
> /*
> * Try next list
> */
> - if (++iter->index >= nr_cpu_ids)
> + if (++iter->index >= nr_dlock_lists)
> return NULL; /* All the entries iterated */
>
> if (list_empty(&iter->head[iter->index].list))
Why these two do not need a similar treatment as alloc_dlist_heads()?
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
