[net-next PATCH v5 2/7] net: Use static_key for XPS maps
From: Amritha Nambiar <hidden>
Date: 2018-06-28 03:33:26
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. This includes static_key 'xps_needed' for XPS and another for 'xps_rxqs_needed' for XPS using Rx queues map. Signed-off-by: Amritha Nambiar <redacted> --- net/core/dev.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 6ca62df..09cba23 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -2081,6 +2081,10 @@ 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); +struct static_key xps_rxqs_needed __read_mostly; +EXPORT_SYMBOL(xps_rxqs_needed); static DEFINE_MUTEX(xps_map_mutex); #define xmap_dereference(P) \ rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))
@@ -2170,12 +2174,14 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset, mutex_lock(&xps_map_mutex); - dev_maps = xmap_dereference(dev->xps_rxqs_map); - if (dev_maps) { - nr_ids = dev->num_rx_queues; - clean_xps_maps(dev, possible_mask, dev_maps, nr_ids, offset, - count, true); - + if (static_key_false(&xps_rxqs_needed)) { + dev_maps = xmap_dereference(dev->xps_rxqs_map); + if (dev_maps) { + nr_ids = dev->num_rx_queues; + clean_xps_maps(dev, possible_mask, dev_maps, nr_ids, + offset, count, true); + } + static_key_slow_dec(&xps_rxqs_needed); } dev_maps = xmap_dereference(dev->xps_cpus_map);
@@ -2189,6 +2195,7 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset, false); out_no_maps: + static_key_slow_dec(&xps_needed); mutex_unlock(&xps_map_mutex); }
@@ -2297,6 +2304,10 @@ 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); + if (is_rxqs_map) + static_key_slow_inc(&xps_rxqs_needed); + for (j = -1; j = attrmask_next(j, possible_mask, nr_ids), j < nr_ids;) { /* copy maps belonging to foreign traffic classes */
@@ -3450,6 +3461,9 @@ 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) {