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Commit f9e06c45 authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
Browse files

tuntap: free XDP dropped packets in a batch 



Thanks to the batched XDP buffs through msg_control. Instead of
calling put_page() for each page which involves a atomic operation,
let's batch them by record the last page that needs to be freed and
its refcnt count and free them in a batch.

Testpmd(virtio-user + vhost_net) + XDP_DROP shows 3.8% improvement.

Before: 4.71Mpps
After : 4.89Mpps

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e4dab1e6

drivers/net/tun.c

+26 −3
Original line number Diff line number Diff line
@@ -188,6 +188,11 @@ struct tun_file { 
	struct xdp_rxq_info xdp_rxq;

};



struct tun_page {

	struct page *page;

	int count;

};



struct tun_flow_entry {

	struct hlist_node hash_link;

	struct rcu_head rcu;
@@ -2377,9 +2382,16 @@ static void tun_sock_write_space(struct sock *sk) 
	kill_fasync(&tfile->fasync, SIGIO, POLL_OUT);

}



static void tun_put_page(struct tun_page *tpage)

{

	if (tpage->page)

		__page_frag_cache_drain(tpage->page, tpage->count);

}



static int tun_xdp_one(struct tun_struct *tun,

		       struct tun_file *tfile,

		       struct xdp_buff *xdp, int *flush)

		       struct xdp_buff *xdp, int *flush,

		       struct tun_page *tpage)

{

	struct tun_xdp_hdr *hdr = xdp->data_hard_start;

	struct virtio_net_hdr *gso = &hdr->gso;
@@ -2390,6 +2402,7 @@ static int tun_xdp_one(struct tun_struct *tun, 
	int buflen = hdr->buflen;

	int err = 0;

	bool skb_xdp = false;

	struct page *page;



	xdp_prog = rcu_dereference(tun->xdp_prog);

	if (xdp_prog) {
@@ -2416,7 +2429,14 @@ static int tun_xdp_one(struct tun_struct *tun, 
		case XDP_PASS:

			break;

		default:

			put_page(virt_to_head_page(xdp->data));

			page = virt_to_head_page(xdp->data);

			if (tpage->page == page) {

				++tpage->count;

			} else {

				tun_put_page(tpage);

				tpage->page = page;

				tpage->count = 1;

			}

			return 0;

		}

	}
@@ -2480,6 +2500,7 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) 
		return -EBADFD;



	if (ctl && (ctl->type == TUN_MSG_PTR)) {

		struct tun_page tpage = {0};

		int n = ctl->num;

		int flush = 0;
@@ -2488,7 +2509,7 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) 


		for (i = 0; i < n; i++) {

			xdp = &((struct xdp_buff *)ctl->ptr)[i];

			tun_xdp_one(tun, tfile, xdp, &flush);

			tun_xdp_one(tun, tfile, xdp, &flush, &tpage);

		}



		if (flush)
@@ -2497,6 +2518,8 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len) 
		rcu_read_unlock();

		local_bh_enable();



		tun_put_page(&tpage);



		ret = total_len;

		goto out;

	}