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| author | Eric Dumazet <edumazet@google.com> | 2014-09-15 04:19:51 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-15 14:41:07 -0400 |
| commit | e11ecddf5128011c936cc5360780190cbc901fdc (patch) | |
| tree | d7723697219a35e66ae7c1dab9e85832a0d19e11 /net/ipv4/tcp_ipv4.c | |
| parent | 13bb5180e82349d9fcfa11cd17b3c1e7b558a902 (diff) | |
| download | lwn-e11ecddf5128011c936cc5360780190cbc901fdc.tar.gz lwn-e11ecddf5128011c936cc5360780190cbc901fdc.zip | |
tcp: use TCP_SKB_CB(skb)->tcp_flags in input path
Input path of TCP do not currently uses TCP_SKB_CB(skb)->tcp_flags,
which is only used in output path.
tcp_recvmsg(), looks at tcp_hdr(skb)->syn for every skb found in receive queue,
and its unfortunate because this bit is located in a cache line right before
the payload.
We can simplify TCP by copying tcp flags into TCP_SKB_CB(skb)->tcp_flags.
This patch does so, and avoids the cache line miss in tcp_recvmsg()
Following patches will
- allow a segment with FIN being coalesced in tcp_try_coalesce()
- simplify tcp_collapse() by not copying the headers.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_ipv4.c')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 7881b96d2b72..006b045716d8 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1638,6 +1638,7 @@ int tcp_v4_rcv(struct sk_buff *skb) TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + skb->len - th->doff * 4); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); + TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); TCP_SKB_CB(skb)->tcp_tw_isn = 0; TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); TCP_SKB_CB(skb)->sacked = 0; |