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Date: Sun, 24 Jun 2018 14:14:02 +0900 (KST)
From: David Miller <davem@...emloft.net>
To: netdev@...r.kernel.org
CC: edumazet@...gle.com
Subject: [PATCH RFC 2/2] 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: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
---
include/linux/netdevice.h | 3 +-
net/core/dev.c | 105 ++++++++++++++++++++++++++++----------
2 files changed, 81 insertions(+), 27 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f176d9873910..c6b377a15869 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -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;
diff --git a/net/core/dev.c b/net/core/dev.c
index aa61b9344b46..dffed642e686 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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)
@@ -5714,12 +5764,16 @@ 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)
- kfree_skb(skb);
+ 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 */
@@ -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.
*/
--
2.17.1
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