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Commit 28d64271 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: attempt high order allocations in sock_alloc_send_pskb() 



Adding paged frags skbs to af_unix sockets introduced a performance
regression on large sends because of additional page allocations, even
if each skb could carry at least 100% more payload than before.

We can instruct sock_alloc_send_pskb() to attempt high order
allocations.

Most of the time, it does a single page allocation instead of 8.

I added an additional parameter to sock_alloc_send_pskb() to
let other users to opt-in for this new feature on followup patches.

Tested:

Before patch :

$ netperf -t STREAM_STREAM
STREAM STREAM TEST
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

 2304  212992  212992    10.00    46861.15

After patch :

$ netperf -t STREAM_STREAM
STREAM STREAM TEST
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

 2304  212992  212992    10.00    57981.11

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e370a723

drivers/net/macvtap.c

+1 −1
Original line number Diff line number Diff line
@@ -524,7 +524,7 @@ static inline struct sk_buff *macvtap_alloc_skb(struct sock *sk, size_t prepad, 
		linear = len;



	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,

				   err);

				   err, 0);

	if (!skb)

		return NULL;

drivers/net/tun.c

+1 −1
Original line number Diff line number Diff line
@@ -949,7 +949,7 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile, 
		linear = len;



	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,

				   &err);

				   &err, 0);

	if (!skb)

		return ERR_PTR(err);

include/net/sock.h

+2 −1
Original line number Diff line number Diff line
@@ -1539,7 +1539,8 @@ extern struct sk_buff *sock_alloc_send_pskb(struct sock *sk, 
						      unsigned long header_len,

						      unsigned long data_len,

						      int noblock,

						      int *errcode);

						      int *errcode,

						      int max_page_order);

extern void *sock_kmalloc(struct sock *sk, int size,

			  gfp_t priority);

extern void sock_kfree_s(struct sock *sk, void *mem, int size);

net/core/sock.c

+51 −49
Original line number Diff line number Diff line
@@ -1741,24 +1741,23 @@ static long sock_wait_for_wmem(struct sock *sk, long timeo) 


struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len,

				     unsigned long data_len, int noblock,

				     int *errcode)

				     int *errcode, int max_page_order)

{

	struct sk_buff *skb;

	struct sk_buff *skb = NULL;

	unsigned long chunk;

	gfp_t gfp_mask;

	long timeo;

	int err;

	int npages = (data_len + (PAGE_SIZE - 1)) >> PAGE_SHIFT;

	struct page *page;

	int i;



	err = -EMSGSIZE;

	if (npages > MAX_SKB_FRAGS)

		goto failure;



	gfp_mask = sk->sk_allocation;

	if (gfp_mask & __GFP_WAIT)

		gfp_mask |= __GFP_REPEAT;



	timeo = sock_sndtimeo(sk, noblock);

	while (1) {

	while (!skb) {

		err = sock_error(sk);

		if (err != 0)

			goto failure;
@@ -1767,50 +1766,52 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len, 
		if (sk->sk_shutdown & SEND_SHUTDOWN)

			goto failure;



		if (atomic_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf) {

			skb = alloc_skb(header_len, gfp_mask);

			if (skb) {

				int i;

		if (atomic_read(&sk->sk_wmem_alloc) >= sk->sk_sndbuf) {

			set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

			set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);

			err = -EAGAIN;

			if (!timeo)

				goto failure;

			if (signal_pending(current))

				goto interrupted;

			timeo = sock_wait_for_wmem(sk, timeo);

			continue;

		}



				/* No pages, we're done... */

				if (!data_len)

					break;

		err = -ENOBUFS;

		gfp_mask = sk->sk_allocation;

		if (gfp_mask & __GFP_WAIT)

			gfp_mask |= __GFP_REPEAT;



		skb = alloc_skb(header_len, gfp_mask);

		if (!skb)

			goto failure;



		skb->truesize += data_len;

				skb_shinfo(skb)->nr_frags = npages;

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

					struct page *page;



					page = alloc_pages(sk->sk_allocation, 0);

					if (!page) {

						err = -ENOBUFS;

						skb_shinfo(skb)->nr_frags = i;

						kfree_skb(skb);

						goto failure;

					}

		for (i = 0; npages > 0; i++) {

			int order = max_page_order;



					__skb_fill_page_desc(skb, i,

							page, 0,

							(data_len >= PAGE_SIZE ?

							 PAGE_SIZE :

							 data_len));

					data_len -= PAGE_SIZE;

			while (order) {

				if (npages >= 1 << order) {

					page = alloc_pages(sk->sk_allocation |

							   __GFP_COMP | __GFP_NOWARN,

							   order);

					if (page)

						goto fill_page;

				}



				/* Full success... */

				break;

				order--;

			}

			err = -ENOBUFS;

			page = alloc_page(sk->sk_allocation);

			if (!page)

				goto failure;

fill_page:

			chunk = min_t(unsigned long, data_len,

				      PAGE_SIZE << order);

			skb_fill_page_desc(skb, i, page, 0, chunk);

			data_len -= chunk;

			npages -= 1 << order;

		}

		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);

		err = -EAGAIN;

		if (!timeo)

			goto failure;

		if (signal_pending(current))

			goto interrupted;

		timeo = sock_wait_for_wmem(sk, timeo);

	}



	skb_set_owner_w(skb, sk);
@@ -1819,6 +1820,7 @@ struct sk_buff *sock_alloc_send_pskb(struct sock *sk, unsigned long header_len, 
interrupted:

	err = sock_intr_errno(timeo);

failure:

	kfree_skb(skb);

	*errcode = err;

	return NULL;

}
@@ -1827,7 +1829,7 @@ EXPORT_SYMBOL(sock_alloc_send_pskb); 
struct sk_buff *sock_alloc_send_skb(struct sock *sk, unsigned long size,

				    int noblock, int *errcode)

{

	return sock_alloc_send_pskb(sk, size, 0, noblock, errcode);

	return sock_alloc_send_pskb(sk, size, 0, noblock, errcode, 0);

}

EXPORT_SYMBOL(sock_alloc_send_skb);

net/packet/af_packet.c

+1 −1
Original line number Diff line number Diff line
@@ -2181,7 +2181,7 @@ static struct sk_buff *packet_alloc_skb(struct sock *sk, size_t prepad, 
		linear = len;



	skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,

				   err);

				   err, 0);

	if (!skb)

		return NULL;