diff options
| author | Eric Dumazet <edumazet@google.com> | 2014-09-24 04:11:22 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-09-28 16:36:48 -0400 |
| commit | cd7d8498c9a5d510c64db38d9f4f4fbc41790f09 (patch) | |
| tree | 4057e715ca8227a081db71f1ec1359011c5c1a00 /net/ipv4/tcp.c | |
| parent | dc83d4d8f6c897022c974a00769b7a6efee6aed8 (diff) | |
tcp: change tcp_skb_pcount() location
Our goal is to access no more than one cache line access per skb in
a write or receive queue when doing the various walks.
After recent TCP_SKB_CB() reorganizations, it is almost done.
Last part is tcp_skb_pcount() which currently uses
skb_shinfo(skb)->gso_segs, which is a terrible choice, because it needs
3 cache lines in current kernel (skb->head, skb->end, and
shinfo->gso_segs are all in 3 different cache lines, far from skb->cb)
This very simple patch reuses space currently taken by tcp_tw_isn
only in input path, as tcp_skb_pcount is only needed for skb stored in
write queue.
This considerably speeds up tcp_ack(), granted we avoid shinfo->tx_flags
to get SKBTX_ACK_TSTAMP, which seems possible.
This also speeds up all sack processing in general.
This speeds up tcp_sendmsg() because it no longer has to access/dirty
shinfo.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp.c')
| -rw-r--r-- | net/ipv4/tcp.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 553b01f52f71..87289e51be00 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -963,7 +963,7 @@ new_segment: skb->ip_summed = CHECKSUM_PARTIAL; tp->write_seq += copy; TCP_SKB_CB(skb)->end_seq += copy; - skb_shinfo(skb)->gso_segs = 0; + tcp_skb_pcount_set(skb, 0); if (!copied) TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_PSH; @@ -1261,7 +1261,7 @@ new_segment: tp->write_seq += copy; TCP_SKB_CB(skb)->end_seq += copy; - skb_shinfo(skb)->gso_segs = 0; + tcp_skb_pcount_set(skb, 0); from += copy; copied += copy; |