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Date: Sun, 15 Mar 2009 02:23:05 +0200
From: "Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: [PATCH 5/7] tcp: simplify tcp_current_mss
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 <ilpo.jarvinen@...sinki.fi>
Cc: Evgeniy Polyakov <zbr@...emap.net>
Cc: Ingo Molnar <mingo@...e.hu>
---
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))
--
1.5.6.5
--
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