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net: add netdev_txq_bql_{enqueue, complete}_prefetchw() helpers 

Add two helpers so that drivers do not have to care of BQL being
available or not.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jim Davis <jim.epost@gmail.com>
Fixes: 29d40c9032 ("net/mlx4_en: Use prefetch in tx path")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-10-08 08:19:27 -07:00 committed by David S. Miller
parent 709c48b39e
commit 535114539b
2 changed files with 32 additions and 2 deletions
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5
drivers/net/ethernet/mellanox/mlx4/en_tx.c
View File

@ -392,7 +392,8 @@ static bool mlx4_en_process_tx_cq(struct net_device *dev,
if (!priv->port_up)
return true;
prefetchw(&ring->tx_queue->dql.limit);
netdev_txq_bql_complete_prefetchw(ring->tx_queue);
index = cons_index & size_mask;
cqe = mlx4_en_get_cqe(buf, index, priv->cqe_size) + factor;
last_nr_txbb = ACCESS_ONCE(ring->last_nr_txbb);
@ -737,7 +738,7 @@ netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev)
vlan_tag = vlan_tx_tag_get(skb);
prefetchw(&ring->tx_queue->dql);
netdev_txq_bql_enqueue_prefetchw(ring->tx_queue);
/* Track current inflight packets for performance analysis */
AVG_PERF_COUNTER(priv->pstats.inflight_avg,

29
include/linux/netdevice.h
View File

@ -30,6 +30,7 @@
#include <linux/bug.h>
#include <linux/delay.h>
#include <linux/atomic.h>
#include <linux/prefetch.h>
#include <asm/cache.h>
#include <asm/byteorder.h>
@ -2480,6 +2481,34 @@ netif_xmit_frozen_or_drv_stopped(const struct netdev_queue *dev_queue)
return dev_queue->state & QUEUE_STATE_DRV_XOFF_OR_FROZEN;
}
/**
* netdev_txq_bql_enqueue_prefetchw - prefetch bql data for write
* @dev_queue: pointer to transmit queue
*
* BQL enabled drivers might use this helper in their ndo_start_xmit(),
* to give appropriate hint to the cpu.
*/
static inline void netdev_txq_bql_enqueue_prefetchw(struct netdev_queue *dev_queue)
{
#ifdef CONFIG_BQL
prefetchw(&dev_queue->dql.num_queued);
#endif
}
/**
* netdev_txq_bql_complete_prefetchw - prefetch bql data for write
* @dev_queue: pointer to transmit queue
*
* BQL enabled drivers might use this helper in their TX completion path,
* to give appropriate hint to the cpu.
*/
static inline void netdev_txq_bql_complete_prefetchw(struct netdev_queue *dev_queue)
{
#ifdef CONFIG_BQL
prefetchw(&dev_queue->dql.limit);
#endif
}
static inline void netdev_tx_sent_queue(struct netdev_queue *dev_queue,
unsigned int bytes)
{