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Date: Wed, 11 Jul 2018 17:15:53 +0800
From: Li RongQing <lirongqing@...du.com>
To: netdev@...r.kernel.org
Subject: [PATCH] net: convert gro_count to bitmask
gro_hash size is 192 bytes, and uses 3 cache lines, if there is few
flows, gro_hash may be not fully used, so it is unnecessary to iterate
all gro_hash in napi_gro_flush(), to occupy unnecessary cacheline.
convert gro_count to a bitmask, and rename it as gro_bitmask, each bit
represents a element of gro_hash, only flush a gro_hash element if the
related bit is set, to speed up napi_gro_flush().
and update gro_bitmask only if it will be changed, to reduce cache
update
Suggested-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Li RongQing <lirongqing@...du.com>
---
include/linux/netdevice.h | 2 +-
net/core/dev.c | 35 +++++++++++++++++++++++------------
2 files changed, 24 insertions(+), 13 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index b683971e500d..df49b36ef378 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -322,7 +322,7 @@ struct napi_struct {
unsigned long state;
int weight;
- unsigned int gro_count;
+ unsigned long gro_bitmask;
int (*poll)(struct napi_struct *, int);
#ifdef CONFIG_NETPOLL
int poll_owner;
diff --git a/net/core/dev.c b/net/core/dev.c
index d13cddcac41f..a08dbdd217a6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5171,9 +5171,11 @@ static void __napi_gro_flush_chain(struct napi_struct *napi, u32 index,
return;
list_del_init(&skb->list);
napi_gro_complete(skb);
- napi->gro_count--;
napi->gro_hash[index].count--;
}
+
+ if (!napi->gro_hash[index].count)
+ clear_bit(index, &napi->gro_bitmask);
}
/* napi->gro_hash[].list contains packets ordered by age.
@@ -5184,8 +5186,10 @@ void napi_gro_flush(struct napi_struct *napi, bool flush_old)
{
u32 i;
- for (i = 0; i < GRO_HASH_BUCKETS; i++)
- __napi_gro_flush_chain(napi, i, flush_old);
+ for (i = 0; i < GRO_HASH_BUCKETS; i++) {
+ if (test_bit(i, &napi->gro_bitmask))
+ __napi_gro_flush_chain(napi, i, flush_old);
+ }
}
EXPORT_SYMBOL(napi_gro_flush);
@@ -5277,8 +5281,8 @@ static void gro_flush_oldest(struct list_head *head)
if (WARN_ON_ONCE(!oldest))
return;
- /* Do not adjust napi->gro_count, caller is adding a new SKB to
- * the chain.
+ /* Do not adjust napi->gro_hash[].count, caller is adding a new
+ * SKB to the chain.
*/
list_del(&oldest->list);
napi_gro_complete(oldest);
@@ -5352,7 +5356,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
if (pp) {
list_del_init(&pp->list);
napi_gro_complete(pp);
- napi->gro_count--;
napi->gro_hash[hash].count--;
}
@@ -5365,7 +5368,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
if (unlikely(napi->gro_hash[hash].count >= MAX_GRO_SKBS)) {
gro_flush_oldest(gro_head);
} else {
- napi->gro_count++;
napi->gro_hash[hash].count++;
}
NAPI_GRO_CB(skb)->count = 1;
@@ -5380,6 +5382,12 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
if (grow > 0)
gro_pull_from_frag0(skb, grow);
ok:
+ if (napi->gro_hash[hash].count)
+ if (!test_bit(hash, &napi->gro_bitmask))
+ set_bit(hash, &napi->gro_bitmask);
+ else if (test_bit(hash, &napi->gro_bitmask))
+ clear_bit(hash, &napi->gro_bitmask);
+
return ret;
normal:
@@ -5778,7 +5786,7 @@ bool napi_complete_done(struct napi_struct *n, int work_done)
NAPIF_STATE_IN_BUSY_POLL)))
return false;
- if (n->gro_count) {
+ if (n->gro_bitmask) {
unsigned long timeout = 0;
if (work_done)
@@ -5987,7 +5995,7 @@ 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 (napi->gro_count && !napi_disable_pending(napi) &&
+ if (napi->gro_bitmask && !napi_disable_pending(napi) &&
!test_and_set_bit(NAPI_STATE_SCHED, &napi->state))
__napi_schedule_irqoff(napi);
@@ -6002,7 +6010,7 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
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;
+ napi->gro_bitmask = 0;
for (i = 0; i < GRO_HASH_BUCKETS; i++) {
INIT_LIST_HEAD(&napi->gro_hash[i].list);
napi->gro_hash[i].count = 0;
@@ -6062,7 +6070,7 @@ void netif_napi_del(struct napi_struct *napi)
napi_free_frags(napi);
flush_gro_hash(napi);
- napi->gro_count = 0;
+ napi->gro_bitmask = 0;
}
EXPORT_SYMBOL(netif_napi_del);
@@ -6104,7 +6112,7 @@ static int napi_poll(struct napi_struct *n, struct list_head *repoll)
goto out_unlock;
}
- if (n->gro_count) {
+ if (n->gro_bitmask) {
/* flush too old packets
* If HZ < 1000, flush all packets.
*/
@@ -9151,6 +9159,9 @@ static struct hlist_head * __net_init netdev_create_hash(void)
/* Initialize per network namespace state */
static int __net_init netdev_init(struct net *net)
{
+ BUILD_BUG_ON(GRO_HASH_BUCKETS >
+ FIELD_SIZEOF(struct napi_struct, gro_bitmask));
+
if (net != &init_net)
INIT_LIST_HEAD(&net->dev_base_head);
--
2.16.2
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