From 0c54b85f2828128274f319a1eb3ce7f604fe2a53 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ilpo=20J=C3=A4rvinen?= Date: Sat, 14 Mar 2009 14:23:05 +0000 Subject: [PATCH] tcp: simplify tcp_current_mss MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit There's very little need for most of the callsites to get tp->xmit_goal_size updated. That will cost us divide as is, so slice the function in two. Also, the only users of the tp->xmit_goal_size are directly behind tcp_current_mss(), so there's no need to store that variable into tcp_sock at all! The drop of xmit_goal_size currently leaves 16-bit hole and some reorganization would again be necessary to change that (but I'm aiming to fill that hole with u16 xmit_goal_size_segs to cache the results of the remaining divide to get that tso on regression). Bring xmit_goal_size parts into tcp.c Signed-off-by: Ilpo Järvinen Cc: Evgeniy Polyakov Cc: Ingo Molnar Signed-off-by: David S. Miller --- include/linux/tcp.h | 1 - include/net/tcp.h | 13 +++++++++++-- net/ipv4/tcp.c | 43 +++++++++++++++++++++++++++++++++++-------- net/ipv4/tcp_input.c | 2 +- net/ipv4/tcp_output.c | 41 +++++++---------------------------------- 5 files changed, 54 insertions(+), 46 deletions(-) diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 4b86ad7..ad2021c 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -248,7 +248,6 @@ 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; /* Goal for segmenting output packets */ /* * Header prediction flags diff --git a/include/net/tcp.h b/include/net/tcp.h index 255ca35..e54c76d 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -481,7 +481,16 @@ static inline void tcp_clear_xmit_timers(struct sock *sk) } extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); -extern unsigned int tcp_current_mss(struct sock *sk, int large); +extern unsigned int tcp_current_mss(struct sock *sk); + +/* Bound MSS / TSO packet size with the half of the window */ +static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) +{ + if (tp->max_window && pktsize > (tp->max_window >> 1)) + return max(tp->max_window >> 1, 68U - tp->tcp_header_len); + else + return pktsize; +} /* tcp.c */ extern void tcp_get_info(struct sock *, struct tcp_info *); @@ -822,7 +831,7 @@ static inline void tcp_push_pending_frames(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); - __tcp_push_pending_frames(sk, tcp_current_mss(sk, 1), tp->nonagle); + __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); } static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index d3f9bee..886596f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -661,6 +661,37 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp) return NULL; } +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; + + xmit_size_goal = mss_now; + + if (large_allowed && sk_can_gso(sk)) { + xmit_size_goal = ((sk->sk_gso_max_size - 1) - + inet_csk(sk)->icsk_af_ops->net_header_len - + inet_csk(sk)->icsk_ext_hdr_len - + tp->tcp_header_len); + + xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal); + xmit_size_goal -= (xmit_size_goal % mss_now); + } + + return xmit_size_goal; +} + +static int tcp_send_mss(struct sock *sk, int *size_goal, int flags) +{ + int mss_now; + + mss_now = tcp_current_mss(sk); + *size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB)); + + return mss_now; +} + static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffset, size_t psize, int flags) { @@ -677,8 +708,7 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffse clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); - mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); - size_goal = tp->xmit_size_goal; + mss_now = tcp_send_mss(sk, &size_goal, flags); copied = 0; err = -EPIPE; @@ -761,8 +791,7 @@ wait_for_memory: if ((err = sk_stream_wait_memory(sk, &timeo)) != 0) goto do_error; - mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); - size_goal = tp->xmit_size_goal; + mss_now = tcp_send_mss(sk, &size_goal, flags); } out: @@ -844,8 +873,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg, /* This should be in poll */ clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); - mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); - size_goal = tp->xmit_size_goal; + mss_now = tcp_send_mss(sk, &size_goal, flags); /* Ok commence sending. */ iovlen = msg->msg_iovlen; @@ -1007,8 +1035,7 @@ wait_for_memory: if ((err = sk_stream_wait_memory(sk, &timeo)) != 0) goto do_error; - mss_now = tcp_current_mss(sk, !(flags&MSG_OOB)); - size_goal = tp->xmit_size_goal; + mss_now = tcp_send_mss(sk, &size_goal, flags); } } diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 311c30f..fae78e3 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2864,7 +2864,7 @@ void tcp_simple_retransmit(struct sock *sk) const struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; - unsigned int mss = tcp_current_mss(sk, 0); + unsigned int mss = tcp_current_mss(sk); u32 prior_lost = tp->lost_out; tcp_for_write_queue(skb, sk) { diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 3256580..c1f259d 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -921,7 +921,7 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) * factor and mss. */ if (tcp_skb_pcount(skb) > 1) - tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk, 1)); + tcp_set_skb_tso_segs(sk, skb, tcp_current_mss(sk)); return 0; } @@ -982,15 +982,6 @@ void tcp_mtup_init(struct sock *sk) icsk->icsk_mtup.probe_size = 0; } -/* Bound MSS / TSO packet size with the half of the window */ -static int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) -{ - if (tp->max_window && pktsize > (tp->max_window >> 1)) - return max(tp->max_window >> 1, 68U - tp->tcp_header_len); - else - return pktsize; -} - /* This function synchronize snd mss to current pmtu/exthdr set. tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts @@ -1037,22 +1028,17 @@ unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) /* Compute the current effective MSS, taking SACKs and IP options, * and even PMTU discovery events into account. */ -unsigned int tcp_current_mss(struct sock *sk, int large_allowed) +unsigned int tcp_current_mss(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); struct dst_entry *dst = __sk_dst_get(sk); u32 mss_now; - u16 xmit_size_goal; - int doing_tso = 0; unsigned header_len; struct tcp_out_options opts; struct tcp_md5sig_key *md5; mss_now = tp->mss_cache; - if (large_allowed && sk_can_gso(sk)) - doing_tso = 1; - if (dst) { u32 mtu = dst_mtu(dst); if (mtu != inet_csk(sk)->icsk_pmtu_cookie) @@ -1070,19 +1056,6 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed) mss_now -= delta; } - xmit_size_goal = mss_now; - - if (doing_tso) { - xmit_size_goal = ((sk->sk_gso_max_size - 1) - - inet_csk(sk)->icsk_af_ops->net_header_len - - inet_csk(sk)->icsk_ext_hdr_len - - tp->tcp_header_len); - - xmit_size_goal = tcp_bound_to_half_wnd(tp, xmit_size_goal); - xmit_size_goal -= (xmit_size_goal % mss_now); - } - tp->xmit_size_goal = xmit_size_goal; - return mss_now; } @@ -1264,7 +1237,7 @@ int tcp_may_send_now(struct sock *sk) struct sk_buff *skb = tcp_send_head(sk); return (skb && - tcp_snd_test(sk, skb, tcp_current_mss(sk, 1), + tcp_snd_test(sk, skb, tcp_current_mss(sk), (tcp_skb_is_last(sk, skb) ? tp->nonagle : TCP_NAGLE_PUSH))); } @@ -1421,7 +1394,7 @@ static int tcp_mtu_probe(struct sock *sk) return -1; /* Very simple search strategy: just double the MSS. */ - mss_now = tcp_current_mss(sk, 0); + mss_now = tcp_current_mss(sk); probe_size = 2 * tp->mss_cache; size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) { @@ -1903,7 +1876,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) return -EHOSTUNREACH; /* Routing failure or similar. */ - cur_mss = tcp_current_mss(sk, 0); + cur_mss = tcp_current_mss(sk); /* If receiver has shrunk his window, and skb is out of * new window, do not retransmit it. The exception is the @@ -2111,7 +2084,7 @@ void tcp_send_fin(struct sock *sk) * unsent frames. But be careful about outgoing SACKS * and IP options. */ - mss_now = tcp_current_mss(sk, 1); + mss_now = tcp_current_mss(sk); if (tcp_send_head(sk) != NULL) { TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_FIN; @@ -2523,7 +2496,7 @@ int tcp_write_wakeup(struct sock *sk) if ((skb = tcp_send_head(sk)) != NULL && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { int err; - unsigned int mss = tcp_current_mss(sk, 0); + unsigned int mss = tcp_current_mss(sk); unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) -- 2.7.4