[net-next PATCH v3 2/5] net: Use static_key for XPS maps
From: Amritha Nambiar <hidden>
Date: 2018-06-05 08:41:34
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Use static_key for XPS maps to reduce the cost of extra map checks, similar to how it is used for RPS and RFS. Signed-off-by: Amritha Nambiar <redacted> --- net/core/dev.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c
index 156acbe..bba755f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -2081,6 +2081,8 @@ int netdev_txq_to_tc(struct net_device *dev, unsigned int txq) EXPORT_SYMBOL(netdev_txq_to_tc); #ifdef CONFIG_XPS +struct static_key xps_needed __read_mostly; +EXPORT_SYMBOL(xps_needed); static DEFINE_MUTEX(xps_map_mutex); #define xmap_dereference(P) \ rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))
@@ -2189,6 +2191,7 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset, out_no_maps: type++; } + static_key_slow_dec(&xps_needed); mutex_unlock(&xps_map_mutex); }
@@ -2309,6 +2312,8 @@ int __netif_set_xps_queue(struct net_device *dev, const unsigned long *mask, if (!new_dev_maps) goto out_no_new_maps; + static_key_slow_inc(&xps_needed); + for (j = -1; j = attrmask_next(j, possible_mask, nr_ids), j < nr_ids;) { /* copy maps belonging to foreign traffic classes */
@@ -3481,6 +3486,9 @@ static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb) struct xps_map *map; int queue_index = -1; + if (!static_key_false(&xps_needed)) + return -1; + rcu_read_lock(); dev_maps = rcu_dereference(dev->xps_cpus_map); if (dev_maps) {