svn commit: r213912 - head/sys/netinet
Lawrence Stewart
lstewart at FreeBSD.org
Sat Oct 16 05:37:45 UTC 2010
Author: lstewart
Date: Sat Oct 16 05:37:45 2010
New Revision: 213912
URL: http://svn.freebsd.org/changeset/base/213912
Log:
- Switch the "net.inet.tcp.reass.cursegments" and
"net.inet.tcp.reass.maxsegments" sysctl variables to be based on UMA zone
stats. The value returned by the cursegments sysctl is approximate owing to
the way in which uma_zone_get_cur is implemented.
- Discontinue use of V_tcp_reass_qsize as a global reassembly segment count
variable in the reassembly implementation. The variable was used without
proper synchronisation and was duplicating accounting done by UMA already. The
lack of synchronisation was particularly problematic on SMP systems
terminating many TCP sessions, resulting in poor TCP performance for
connections with non-zero packet loss.
Sponsored by: FreeBSD Foundation
Reviewed by: andre, gnn, rpaulo (as part of a larger patch)
MFC after: 2 weeks
Modified:
head/sys/netinet/tcp_reass.c
Modified: head/sys/netinet/tcp_reass.c
==============================================================================
--- head/sys/netinet/tcp_reass.c Sat Oct 16 04:41:45 2010 (r213911)
+++ head/sys/netinet/tcp_reass.c Sat Oct 16 05:37:45 2010 (r213912)
@@ -74,19 +74,22 @@ __FBSDID("$FreeBSD$");
#include <netinet/tcp_debug.h>
#endif /* TCPDEBUG */
+static int tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS);
+static int tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS);
+
SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
"TCP Segment Reassembly Queue");
static VNET_DEFINE(int, tcp_reass_maxseg) = 0;
#define V_tcp_reass_maxseg VNET(tcp_reass_maxseg)
-SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
- &VNET_NAME(tcp_reass_maxseg), 0,
+SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN,
+ &VNET_NAME(tcp_reass_maxseg), 0, &tcp_reass_sysctl_maxseg, "I",
"Global maximum number of TCP Segments in Reassembly Queue");
static VNET_DEFINE(int, tcp_reass_qsize) = 0;
#define V_tcp_reass_qsize VNET(tcp_reass_qsize)
-SYSCTL_VNET_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
- &VNET_NAME(tcp_reass_qsize), 0,
+SYSCTL_VNET_PROC(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
+ &VNET_NAME(tcp_reass_qsize), 0, &tcp_reass_sysctl_qsize, "I",
"Global number of TCP Segments currently in Reassembly Queue");
static VNET_DEFINE(int, tcp_reass_maxqlen) = 48;
@@ -148,7 +151,6 @@ tcp_reass_flush(struct tcpcb *tp)
m_freem(qe->tqe_m);
uma_zfree(V_tcp_reass_zone, qe);
tp->t_segqlen--;
- V_tcp_reass_qsize--;
}
KASSERT((tp->t_segqlen == 0),
@@ -156,6 +158,20 @@ tcp_reass_flush(struct tcpcb *tp)
tp, tp->t_segqlen));
}
+static int
+tcp_reass_sysctl_maxseg(SYSCTL_HANDLER_ARGS)
+{
+ V_tcp_reass_maxseg = uma_zone_get_max(V_tcp_reass_zone);
+ return (sysctl_handle_int(oidp, arg1, arg2, req));
+}
+
+static int
+tcp_reass_sysctl_qsize(SYSCTL_HANDLER_ARGS)
+{
+ V_tcp_reass_qsize = uma_zone_get_cur(V_tcp_reass_zone);
+ return (sysctl_handle_int(oidp, arg1, arg2, req));
+}
+
int
tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
{
@@ -184,12 +200,10 @@ tcp_reass(struct tcpcb *tp, struct tcphd
* Limit the number of segments in the reassembly queue to prevent
* holding on to too many segments (and thus running out of mbufs).
* Make sure to let the missing segment through which caused this
- * queue. Always keep one global queue entry spare to be able to
- * process the missing segment.
+ * queue.
*/
if (th->th_seq != tp->rcv_nxt &&
- (V_tcp_reass_qsize + 1 >= V_tcp_reass_maxseg ||
- tp->t_segqlen >= V_tcp_reass_maxqlen)) {
+ tp->t_segqlen >= V_tcp_reass_maxqlen) {
V_tcp_reass_overflows++;
TCPSTAT_INC(tcps_rcvmemdrop);
m_freem(m);
@@ -209,7 +223,6 @@ tcp_reass(struct tcpcb *tp, struct tcphd
return (0);
}
tp->t_segqlen++;
- V_tcp_reass_qsize++;
/*
* Find a segment which begins after this one does.
@@ -236,7 +249,6 @@ tcp_reass(struct tcpcb *tp, struct tcphd
m_freem(m);
uma_zfree(V_tcp_reass_zone, te);
tp->t_segqlen--;
- V_tcp_reass_qsize--;
/*
* Try to present any queued data
* at the left window edge to the user.
@@ -273,7 +285,6 @@ tcp_reass(struct tcpcb *tp, struct tcphd
m_freem(q->tqe_m);
uma_zfree(V_tcp_reass_zone, q);
tp->t_segqlen--;
- V_tcp_reass_qsize--;
q = nq;
}
@@ -310,7 +321,6 @@ present:
sbappendstream_locked(&so->so_rcv, q->tqe_m);
uma_zfree(V_tcp_reass_zone, q);
tp->t_segqlen--;
- V_tcp_reass_qsize--;
q = nq;
} while (q && q->tqe_th->th_seq == tp->rcv_nxt);
ND6_HINT(tp);
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