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Commit 07d78363 authored by David Miller's avatar David Miller Committed by David S. Miller
Browse files

net: Convert NAPI gro list into a small hash table. 



Improve the performance of GRO receive by splitting flows into
multiple hash chains.

Suggested-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d4546c25

include/linux/netdevice.h

+2 −1
Original line number Diff line number Diff line
@@ -305,6 +305,7 @@ int __init netdev_boot_setup(char *str); 
/*

 * Structure for NAPI scheduling similar to tasklet but with weighting

 */

#define GRO_HASH_BUCKETS	8

struct napi_struct {

	/* The poll_list must only be managed by the entity which

	 * changes the state of the NAPI_STATE_SCHED bit.  This means
@@ -322,7 +323,7 @@ struct napi_struct { 
	int			poll_owner;

#endif

	struct net_device	*dev;

	struct list_head	gro_list;

	struct list_head	gro_hash[GRO_HASH_BUCKETS];

	struct sk_buff		*skb;

	struct hrtimer		timer;

	struct list_head	dev_list;

net/core/dev.c

+79 −26
Original line number Diff line number Diff line
@@ -4875,15 +4875,12 @@ static int napi_gro_complete(struct sk_buff *skb) 
	return netif_receive_skb_internal(skb);

}



/* napi->gro_list contains packets ordered by age.

 * youngest packets at the head of it.

 * Complete skbs in reverse order to reduce latencies.

 */

void napi_gro_flush(struct napi_struct *napi, bool flush_old)

static void __napi_gro_flush_chain(struct napi_struct *napi, struct list_head *head,

				   bool flush_old)

{

	struct sk_buff *skb, *p;



	list_for_each_entry_safe_reverse(skb, p, &napi->gro_list, list) {

	list_for_each_entry_safe_reverse(skb, p, head, list) {

		if (flush_old && NAPI_GRO_CB(skb)->age == jiffies)

			return;

		list_del_init(&skb->list);
@@ -4891,15 +4888,33 @@ void napi_gro_flush(struct napi_struct *napi, bool flush_old) 
		napi->gro_count--;

	}

}



/* napi->gro_hash contains packets ordered by age.

 * youngest packets at the head of it.

 * Complete skbs in reverse order to reduce latencies.

 */

void napi_gro_flush(struct napi_struct *napi, bool flush_old)

{

	int i;



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

		struct list_head *head = &napi->gro_hash[i];



		__napi_gro_flush_chain(napi, head, flush_old);

	}

}

EXPORT_SYMBOL(napi_gro_flush);



static void gro_list_prepare(struct napi_struct *napi, struct sk_buff *skb)

static struct list_head *gro_list_prepare(struct napi_struct *napi,

					  struct sk_buff *skb)

{

	unsigned int maclen = skb->dev->hard_header_len;

	u32 hash = skb_get_hash_raw(skb);

	struct list_head *head;

	struct sk_buff *p;



	list_for_each_entry(p, &napi->gro_list, list) {

	head = &napi->gro_hash[hash & (GRO_HASH_BUCKETS - 1)];

	list_for_each_entry(p, head, list) {

		unsigned long diffs;



		NAPI_GRO_CB(p)->flush = 0;
@@ -4922,6 +4937,8 @@ static void gro_list_prepare(struct napi_struct *napi, struct sk_buff *skb) 
				       maclen);

		NAPI_GRO_CB(p)->same_flow = !diffs;

	}



	return head;

}



static void skb_gro_reset_offset(struct sk_buff *skb)
@@ -4964,11 +4981,45 @@ static void gro_pull_from_frag0(struct sk_buff *skb, int grow) 
	}

}



static void gro_flush_oldest(struct napi_struct *napi)

{

	struct sk_buff *oldest = NULL;

	unsigned long age = jiffies;

	int i;



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

		struct list_head *head = &napi->gro_hash[i];

		struct sk_buff *skb;



		if (list_empty(head))

			continue;



		skb = list_last_entry(head, struct sk_buff, list);

		if (!oldest || time_before(NAPI_GRO_CB(skb)->age, age)) {

			oldest = skb;

			age = NAPI_GRO_CB(skb)->age;

		}

	}



	/* We are called with napi->gro_count >= MAX_GRO_SKBS, so this is

	 * impossible.

	 */

	if (WARN_ON_ONCE(!oldest))

		return;



	/* Do not adjust napi->gro_count, caller is adding a new SKB to

	 * the chain.

	 */

	list_del(&oldest->list);

	napi_gro_complete(oldest);

}



static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff *skb)

{

	struct list_head *head = &offload_base;

	struct packet_offload *ptype;

	__be16 type = skb->protocol;

	struct list_head *gro_head;

	struct sk_buff *pp = NULL;

	enum gro_result ret;

	int same_flow;
@@ -4977,7 +5028,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff 
	if (netif_elide_gro(skb->dev))

		goto normal;



	gro_list_prepare(napi, skb);

	gro_head = gro_list_prepare(napi, skb);



	rcu_read_lock();

	list_for_each_entry_rcu(ptype, head, list) {
@@ -5011,7 +5062,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff 
			NAPI_GRO_CB(skb)->csum_valid = 0;

		}



		pp = ptype->callbacks.gro_receive(&napi->gro_list, skb);

		pp = ptype->callbacks.gro_receive(gro_head, skb);

		break;

	}

	rcu_read_unlock();
@@ -5040,11 +5091,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff 
		goto normal;



	if (unlikely(napi->gro_count >= MAX_GRO_SKBS)) {

		struct sk_buff *nskb;



		nskb = list_last_entry(&napi->gro_list, struct sk_buff, list);

		list_del(&nskb->list);

		napi_gro_complete(nskb);

		gro_flush_oldest(napi);

	} else {

		napi->gro_count++;

	}
@@ -5052,7 +5099,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff 
	NAPI_GRO_CB(skb)->age = jiffies;

	NAPI_GRO_CB(skb)->last = skb;

	skb_shinfo(skb)->gso_size = skb_gro_len(skb);

	list_add(&skb->list, &napi->gro_list);

	list_add(&skb->list, gro_head);

	ret = GRO_HELD;



pull:
@@ -5458,7 +5505,7 @@ bool napi_complete_done(struct napi_struct *n, int work_done) 
				 NAPIF_STATE_IN_BUSY_POLL)))

		return false;



	if (!list_empty(&n->gro_list)) {

	if (n->gro_count) {

		unsigned long timeout = 0;



		if (work_done)
@@ -5667,7 +5714,7 @@ static enum hrtimer_restart napi_watchdog(struct hrtimer *timer) 
	/* Note : we use a relaxed variant of napi_schedule_prep() not setting

	 * NAPI_STATE_MISSED, since we do not react to a device IRQ.

	 */

	if (!list_empty(&napi->gro_list) && !napi_disable_pending(napi) &&

	if (napi->gro_count && !napi_disable_pending(napi) &&

	    !test_and_set_bit(NAPI_STATE_SCHED, &napi->state))

		__napi_schedule_irqoff(napi);
@@ -5677,11 +5724,14 @@ static enum hrtimer_restart napi_watchdog(struct hrtimer *timer) 
void netif_napi_add(struct net_device *dev, struct napi_struct *napi,

		    int (*poll)(struct napi_struct *, int), int weight)

{

	int i;



	INIT_LIST_HEAD(&napi->poll_list);

	hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);

	napi->timer.function = napi_watchdog;

	napi->gro_count = 0;

	INIT_LIST_HEAD(&napi->gro_list);

	for (i = 0; i < GRO_HASH_BUCKETS; i++)

		INIT_LIST_HEAD(&napi->gro_hash[i]);

	napi->skb = NULL;

	napi->poll = poll;

	if (weight > NAPI_POLL_WEIGHT)
@@ -5714,13 +5764,17 @@ void napi_disable(struct napi_struct *n) 
}

EXPORT_SYMBOL(napi_disable);



static void gro_list_free(struct list_head *head)

static void flush_gro_hash(struct napi_struct *napi)

{

	struct sk_buff *skb, *p;

	int i;



	list_for_each_entry_safe(skb, p, head, list)

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

		struct sk_buff *skb, *n;



		list_for_each_entry_safe(skb, n, &napi->gro_hash[i], list)

			kfree_skb(skb);

	}

}



/* Must be called in process context */

void netif_napi_del(struct napi_struct *napi)
@@ -5731,8 +5785,7 @@ void netif_napi_del(struct napi_struct *napi) 
	list_del_init(&napi->dev_list);

	napi_free_frags(napi);



	gro_list_free(&napi->gro_list);

	INIT_LIST_HEAD(&napi->gro_list);

	flush_gro_hash(napi);

	napi->gro_count = 0;

}

EXPORT_SYMBOL(netif_napi_del);
@@ -5775,7 +5828,7 @@ static int napi_poll(struct napi_struct *n, struct list_head *repoll) 
		goto out_unlock;

	}



	if (!list_empty(&n->gro_list)) {

	if (n->gro_count) {

		/* flush too old packets

		 * If HZ < 1000, flush all packets.

		 */