Currently t_template of tcpcb is a mbuf cluster. This happened when
max_linkhdr is increased from 16 to 64 (1.44 of
sys/kern/uipc_domain.c).
I found this because I wonder why my company, IIJ's HTTP proxy servers
started using a lot of mbuf clusters after a certain version.
ok?
It doesn't seem to be necessary to have any extra space for the
t_template of tcpcb.
Index: sys/netinet/tcp_subr.c
===================================================================
RCS file: /cvs/src/sys/netinet/tcp_subr.c,v
retrieving revision 1.171
diff -u -p -r1.171 tcp_subr.c
--- sys/netinet/tcp_subr.c 8 May 2018 15:10:33 -0000 1.171
+++ sys/netinet/tcp_subr.c 12 Jun 2018 04:29:20 -0000
@@ -207,20 +207,15 @@ tcp_template(struct tcpcb *tp)
break;
#endif /* INET6 */
}
- m->m_len += sizeof (struct tcphdr);
- /*
- * The link header, network header, TCP header, and TCP options
- * all must fit in this mbuf. For now, assume the worst case of
- * TCP options size. Eventually, compute this from tp flags.
- */
- if (m->m_len + MAX_TCPOPTLEN + max_linkhdr >= MHLEN) {
+ if (m->m_len + sizeof(struct tcphdr) >= MHLEN) {
MCLGET(m, M_DONTWAIT);
if ((m->m_flags & M_EXT) == 0) {
m_free(m);
return (0);
}
}
+ m->m_len += sizeof(struct tcphdr);
}
switch(tp->pf) {
