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xsk: Change the tx writeable condition 

Modify the tx writeable condition from the queue is not full to the
number of present tx queues is less than the half of the total number
of queues. Because the tx queue not full is a very short time, this will
cause a large number of EPOLLOUT events, and cause a large number of
process wake up.

Fixes: 35fcde7f8d ("xsk: support for Tx")
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/508fef55188d4e1160747ead64c6dcda36735880.1606555939.git.xuanzhuo@linux.alibaba.com
This commit is contained in:
Xuan Zhuo 2020-12-01 21:56:58 +08:00 committed by Daniel Borkmann
parent f5da54187e
commit 3413f04141
2 changed files with 19 additions and 3 deletions
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16
net/xdp/xsk.c
View File

@ -211,6 +211,14 @@ static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len,
return 0;
}
static bool xsk_tx_writeable(struct xdp_sock *xs)
{
if (xskq_cons_present_entries(xs->tx) > xs->tx->nentries / 2)
return false;
return true;
}
static bool xsk_is_bound(struct xdp_sock *xs)
{
if (READ_ONCE(xs->state) == XSK_BOUND) {
@ -296,7 +304,8 @@ void xsk_tx_release(struct xsk_buff_pool *pool)
rcu_read_lock();
list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list) {
__xskq_cons_release(xs->tx);
xs->sk.sk_write_space(&xs->sk);
if (xsk_tx_writeable(xs))
xs->sk.sk_write_space(&xs->sk);
}
rcu_read_unlock();
}
@ -436,7 +445,8 @@ static int xsk_generic_xmit(struct sock *sk)
out:
if (sent_frame)
sk->sk_write_space(sk);
if (xsk_tx_writeable(xs))
sk->sk_write_space(sk);
mutex_unlock(&xs->mutex);
return err;
@ -493,7 +503,7 @@ static __poll_t xsk_poll(struct file *file, struct socket *sock,
if (xs->rx && !xskq_prod_is_empty(xs->rx))
mask |= EPOLLIN | EPOLLRDNORM;
if (xs->tx && !xskq_cons_is_full(xs->tx))
if (xs->tx && xsk_tx_writeable(xs))
mask |= EPOLLOUT | EPOLLWRNORM;
return mask;

6
net/xdp/xsk_queue.h
View File

@ -264,6 +264,12 @@ static inline bool xskq_cons_is_full(struct xsk_queue *q)
q->nentries;
}
static inline u32 xskq_cons_present_entries(struct xsk_queue *q)
{
/* No barriers needed since data is not accessed */
return READ_ONCE(q->ring->producer) - READ_ONCE(q->ring->consumer);
}
/* Functions for producers */
static inline bool xskq_prod_is_full(struct xsk_queue *q)