use just one mbuf when sending small data segments;

truncate sbspace to our max window

SCCS-vsn: sys/netinet/tcp_output.c 7.14

diff --git a/usr/src/sys/netinet/tcp_output.c b/usr/src/sys/netinet/tcp_output.c
index 8dc2b7e..400d45e 100644 (file)
--- a/usr/src/sys/netinet/tcp_output.c
+++ b/usr/src/sys/netinet/tcp_output.c
@@ -9,7 +9,7 @@
  * software without specific prior written permission. This software
  * is provided ``as is'' without express or implied warranty.
  *
  * software without specific prior written permission. This software
  * is provided ``as is'' without express or implied warranty.
  *

- *     @(#)tcp_output.c        7.13.1.2 (Berkeley) %G%
+ *     @(#)tcp_output.c        7.14 (Berkeley) %G%

  */
 
 #include "param.h"
  */
 
 #include "param.h"


@@ -48,7 +48,7 @@ tcp_output(tp)
        register struct tcpcb *tp;
 {
        register struct socket *so = tp->t_inpcb->inp_socket;
        register struct tcpcb *tp;
 {
        register struct socket *so = tp->t_inpcb->inp_socket;

-       register int len, win;
+       register long len, win;

        struct mbuf *m0;
        int off, flags, error;
        register struct mbuf *m;
        struct mbuf *m0;
        int off, flags, error;
        register struct mbuf *m;


@@ -213,8 +213,11 @@ send:
        MGET(m, M_DONTWAIT, MT_HEADER);
        if (m == NULL)
                return (ENOBUFS);
        MGET(m, M_DONTWAIT, MT_HEADER);
        if (m == NULL)
                return (ENOBUFS);

-       m->m_off = MMAXOFF - sizeof (struct tcpiphdr);
+#define        MAXLINKHDR      32              /* belongs elsewhere */
+#define        DATASPACE  (MMAXOFF - (MMINOFF + MAXLINKHDR + sizeof (struct tcpiphdr)))
+       m->m_off = MMINOFF + MAXLINKHDR;

        m->m_len = sizeof (struct tcpiphdr);
        m->m_len = sizeof (struct tcpiphdr);

+       ti = mtod(m, struct tcpiphdr *);

        if (len) {
                if (tp->t_force && len == 1)
                        tcpstat.tcps_sndprobe++;
        if (len) {
                if (tp->t_force && len == 1)
                        tcpstat.tcps_sndprobe++;


@@ -225,9 +228,15 @@ send:
                        tcpstat.tcps_sndpack++;
                        tcpstat.tcps_sndbyte += len;
                }
                        tcpstat.tcps_sndpack++;
                        tcpstat.tcps_sndbyte += len;
                }

-               m->m_next = m_copy(so->so_snd.sb_mb, off, len);
-               if (m->m_next == 0)
-                       len = 0;
+               if (len <= DATASPACE) {
+                       m_copydata(so->so_snd.sb_mb, off, len,
+                           mtod(m, caddr_t) + sizeof(struct tcpiphdr));
+                       m->m_len += len;
+               } else {
+                       m->m_next = m_copy(so->so_snd.sb_mb, off, len);
+                       if (m->m_next == 0)
+                               len = 0;
+               }

        } else if (tp->t_flags & TF_ACKNOW)
                tcpstat.tcps_sndacks++;
        else if (flags & (TH_SYN|TH_FIN|TH_RST))
        } else if (tp->t_flags & TF_ACKNOW)
                tcpstat.tcps_sndacks++;
        else if (flags & (TH_SYN|TH_FIN|TH_RST))


@@ -237,7 +246,6 @@ send:
        else
                tcpstat.tcps_sndwinup++;
 
        else
                tcpstat.tcps_sndwinup++;
 

-       ti = mtod(m, struct tcpiphdr *);

        if (tp->t_template == 0)
                panic("tcp_output");
        bcopy((caddr_t)tp->t_template, (caddr_t)ti, sizeof (struct tcpiphdr));
        if (tp->t_template == 0)
                panic("tcp_output");
        bcopy((caddr_t)tp->t_template, (caddr_t)ti, sizeof (struct tcpiphdr));


@@ -294,6 +302,8 @@ send:
         */
        if (win < so->so_rcv.sb_hiwat / 4 && win < tp->t_maxseg)
                win = 0;
         */
        if (win < so->so_rcv.sb_hiwat / 4 && win < tp->t_maxseg)
                win = 0;

+       if (win > IP_MAXPACKET)
+               win = IP_MAXPACKET;

        if (win < (int)(tp->rcv_adv - tp->rcv_nxt))
                win = (int)(tp->rcv_adv - tp->rcv_nxt);
        if (win > IP_MAXPACKET)
        if (win < (int)(tp->rcv_adv - tp->rcv_nxt))
                win = (int)(tp->rcv_adv - tp->rcv_nxt);
        if (win > IP_MAXPACKET)