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authorEric Dumazet <edumazet@google.com>2012-08-07 02:19:56 +0000
committerDavid S. Miller <davem@davemloft.net>2012-08-07 16:24:55 -0700
commit425f09ab7d1c9da6ca4137dd639cb6fe3f8a88f3 (patch)
tree49c586d8025f671a8e47415f4364bfb818534569 /include/net
parente07b94f1352723994d8b588ac5ed8af91bcc9fb6 (diff)
net: output path optimizations
1) Avoid dirtying neighbour's confirmed field. TCP workloads hits this cache line for each incoming ACK. Lets write n->confirmed only if there is a jiffie change. 2) Optimize neigh_hh_output() for the common Ethernet case, were hh_len is less than 16 bytes. Replace the memcpy() call by two inlined 64bit load/stores on x86_64. Bench results using udpflood test, with -C option (MSG_CONFIRM flag added to sendto(), to reproduce the n->confirmed dirtying on UDP) 24 threads doing 1.000.000 UDP sendto() on dummy device, 4 runs. before : 2.247s, 2.235s, 2.247s, 2.318s after : 1.884s, 1.905s, 1.891s, 1.895s Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/dst.h10
-rw-r--r--include/net/neighbour.h14
2 files changed, 16 insertions, 8 deletions
diff --git a/include/net/dst.h b/include/net/dst.h
index baf597890064..77f52f7dc823 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -396,11 +396,15 @@ static inline void dst_confirm(struct dst_entry *dst)
static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
struct sk_buff *skb)
{
- struct hh_cache *hh;
+ const struct hh_cache *hh;
+
+ if (dst->pending_confirm) {
+ unsigned long now = jiffies;
- if (unlikely(dst->pending_confirm)) {
- n->confirmed = jiffies;
dst->pending_confirm = 0;
+ /* avoid dirtying neighbour */
+ if (n->confirmed != now)
+ n->confirmed = now;
}
hh = &n->hh;
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 344d8988842a..0dab173e27da 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -334,18 +334,22 @@ static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
}
#endif
-static inline int neigh_hh_output(struct hh_cache *hh, struct sk_buff *skb)
+static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
{
unsigned int seq;
int hh_len;
do {
- int hh_alen;
-
seq = read_seqbegin(&hh->hh_lock);
hh_len = hh->hh_len;
- hh_alen = HH_DATA_ALIGN(hh_len);
- memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
+ if (likely(hh_len <= HH_DATA_MOD)) {
+ /* this is inlined by gcc */
+ memcpy(skb->data - HH_DATA_MOD, hh->hh_data, HH_DATA_MOD);
+ } else {
+ int hh_alen = HH_DATA_ALIGN(hh_len);
+
+ memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
+ }
} while (read_seqretry(&hh->hh_lock, seq));
skb_push(skb, hh_len);