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net: Use static_key for XPS maps 

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 <amritha.nambiar@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Amritha Nambiar 2018-06-29 21:26:46 -07:00 committed by David S. Miller
parent 80d19669ec
commit 04157469b7
1 changed files with 25 additions and 6 deletions
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31
net/core/dev.c
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@ -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))
@ -2168,14 +2172,18 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
struct xps_dev_maps *dev_maps;
unsigned int nr_ids;
if (!static_key_false(&xps_needed))
return;
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);
}
}
dev_maps = xmap_dereference(dev->xps_cpus_map);
@ -2189,6 +2197,10 @@ static void netif_reset_xps_queues(struct net_device *dev, u16 offset,
false);
out_no_maps:
if (static_key_enabled(&xps_rxqs_needed))
static_key_slow_dec(&xps_rxqs_needed);
static_key_slow_dec(&xps_needed);
mutex_unlock(&xps_map_mutex);
}
@ -2297,6 +2309,10 @@ 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 = netif_attrmask_next(j, possible_mask, nr_ids),
j < nr_ids;) {
/* copy maps belonging to foreign traffic classes */
@ -3450,6 +3466,9 @@ 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) {