--- share/man/man4/tcp.4.orig +++ share/man/man4/tcp.4 @@ -436,6 +436,20 @@ Reseeding should not be necessary, and will break .Dv TIME_WAIT recycling for a few minutes. +.It Va reass.cursegments +The current total number of segments present in all reassembly queues. +.It Va reass.maxsegments +The maximum limit on the total number of segments across all reassembly +queues. +The limit can be adjusted as a tunable. +.It Va reass.maxqueuelen +The maximum number of segments allowed in each reassembly queue. +By default, the system chooses a limit based on each TCP connection's +receive buffer size and maximum segment size (MSS). +The actual limit applied to a session's reassembly queue will be the lower of +the system-calculated automatic limit and the user-specified +.Va reass.maxqueuelen +limit. .It Va rexmit_min , rexmit_slop Adjust the retransmit timer calculation for .Tn TCP . --- sys/netinet/tcp_reass.c.orig +++ sys/netinet/tcp_reass.c @@ -96,6 +96,11 @@ static uma_zone_t tcp_reass_zone; +static u_int tcp_reass_maxqueuelen = 100; +SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, + &tcp_reass_maxqueuelen, 0, + "Maximum number of TCP Segments per Reassembly Queue"); + /* Initialize TCP reassembly queue */ static void tcp_reass_zone_change(void *tag) @@ -184,6 +189,10 @@ * socket receive buffer determines our advertised window and grows * automatically when socket buffer autotuning is enabled. Use it as the * basis for our queue limit. + * + * However, allow the user to specify a ceiling for the number of + * segments in each queue. + * * Always let the missing segment through which caused this queue. * NB: Access to the socket buffer is left intentionally unlocked as we * can tolerate stale information here. @@ -194,7 +203,8 @@ * is understood. */ if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && - tp->t_segqlen >= (so->so_rcv.sb_hiwat / tp->t_maxseg) + 1) { + tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, + tcp_reass_maxqueuelen)) { tcp_reass_overflows++; TCPSTAT_INC(tcps_rcvmemdrop); m_freem(m);