diff options
| author | Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> | 2009-03-14 22:45:16 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-03-15 20:09:55 -0700 |
| commit | 2a3a041c4e2c1685e668b280c121a5a40a029a03 (patch) | |
| tree | dab327c0cbebec79968c3c2207d064a9152857f0 | |
| parent | 0c54b85f2828128274f319a1eb3ce7f604fe2a53 (diff) | |
tcp: cache result of earlier divides when mss-aligning things
The results is very unlikely change every so often so we
hardly need to divide again after doing that once for a
connection. Yet, if divide still becomes necessary we
detect that and do the right thing and again settle for
non-divide state. Takes the u16 space which was previously
taken by the plain xmit_size_goal.
This should take care part of the tso vs non-tso difference
we found earlier.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/tcp.h | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp.c | 14 |
2 files changed, 13 insertions, 2 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index ad2021ccc55..9d5078bd23a 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -248,6 +248,7 @@ struct tcp_sock { /* inet_connection_sock has to be the first member of tcp_sock */ struct inet_connection_sock inet_conn; u16 tcp_header_len; /* Bytes of tcp header to send */ + u16 xmit_size_goal_segs; /* Goal for segmenting output packets */ /* * Header prediction flags diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 886596ff0aa..0db9f3b984f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -665,7 +665,7 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now, int large_allowed) { struct tcp_sock *tp = tcp_sk(sk); - u32 xmit_size_goal; + u32 xmit_size_goal, old_size_goal; xmit_size_goal = mss_now; @@ -676,7 +676,17 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now, tp->tcp_header_len); xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal); - xmit_size_goal -= (xmit_size_goal % mss_now); + + /* We try hard to avoid divides here */ + old_size_goal = tp->xmit_size_goal_segs * mss_now; + + if (likely(old_size_goal <= xmit_size_goal && + old_size_goal + mss_now > xmit_size_goal)) { + xmit_size_goal = old_size_goal; + } else { + tp->xmit_size_goal_segs = xmit_size_goal / mss_now; + xmit_size_goal = tp->xmit_size_goal_segs * mss_now; + } } return xmit_size_goal; |