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Code Issues Releases Activity

The TCPPCAP debugging feature caches recently-used mbufs for use in

Browse Source 
debugging TCP connections. This commit provides a mechanism to free those
mbufs when the system is under memory pressure.

Because this will result in lost debugging information, the behavior is
controllable by a sysctl. The default setting is to free the mbufs.

Reviewed by:	gnn
Approved by:	re (gjb)
Differential Revision:	https://reviews.freebsd.org/D6931
Input from:	novice_techie.com
This commit is contained in:
Jonathan T. Looney 2016-07-06 16:17:13 +00:00
parent 7e12dfe5ef
commit 24b9bb5614
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=302374
3 changed files with 13 additions and 0 deletions
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4
sys/netinet/tcp_pcap.c
View File

@ -42,9 +42,13 @@
#define M_LEADINGSPACE_NOWRITE(m) \
((m)->m_data - M_START(m))
int tcp_pcap_aggressive_free = 1;
static int tcp_pcap_clusters_referenced_cur = 0;
static int tcp_pcap_clusters_referenced_max = 0;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_pcap_aggressive_free,
CTLFLAG_RW, &tcp_pcap_aggressive_free, 0,
"Free saved packets when the memory system comes under pressure");
SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_pcap_clusters_referenced_cur,
CTLFLAG_RD, &tcp_pcap_clusters_referenced_cur, 0,
"Number of clusters currently referenced on TCP PCAP queues");

2
sys/netinet/tcp_pcap.h
View File

@ -36,4 +36,6 @@ void tcp_pcap_tcpcb_init(struct tcpcb *tp);
void tcp_pcap_set_sock_max(struct mbufq *queue, int newval);
int tcp_pcap_get_sock_max(struct mbufq *queue);
extern int tcp_pcap_aggressive_free;
#endif /* _NETINET_TCP_PCAP_H_ */

7
sys/netinet/tcp_subr.c
View File

@ -1605,6 +1605,13 @@ tcp_drain(void)
if ((tcpb = intotcpcb(inpb)) != NULL) {
tcp_reass_flush(tcpb);
tcp_clean_sackreport(tcpb);
#ifdef TCPPCAP
if (tcp_pcap_aggressive_free) {
/* Free the TCP PCAP queues. */
tcp_pcap_drain(&(tcpb->t_inpkts));
tcp_pcap_drain(&(tcpb->t_outpkts));
}
#endif
}
INP_WUNLOCK(inpb);
}