Date: Sat, 24 Jan 2009 23:26:20 +0100 From: Marcin Gryszkalis <mg@fork.pl> To: freebsd-net@freebsd.org Subject: FreeBSD 7.1 - syncache, tcp queue Message-ID: <200901242326.20595.mg@fork.pl>
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I upgraded 2 machines to 7.1 (i386 and amd64) - both are running nginx web server and both are experiencing problem with resetting connections. c -> s TCP 56473 > 80 [SYN] Seq=0 Win=5840 Len=0 MSS=1460 TSV=173160194 TSER=0 WS=6 s -> c TCP 80 > 56473 [SYN, ACK] Seq=0 Ack=1 Win=65535 [TCP CHECKSUM INCORRECT] Len=0 MSS=1460 WS=3 TSV=2680138265 TSER=173160194 c -> s TCP 56473 > 80 [ACK] Seq=1 Ack=1 Win=5888 Len=0 TSV=173160239 TSER=2680138265 s -> c TCP 80 > 56473 [RST] Seq=1 Win=0 [TCP CHECKSUM INCORRECT] Len=0 s -> c HTTP GET / HTTP/1.0 ... on the i386 I can see in debug log: kernel: TCP: [83.6.208.139]:1909 to [62.233.226.70]:80; syncache_socket: Socket create failed due to limits or memory shortage kernel: TCP: [83.6.208.139]:1909 to [62.233.226.70]:80 tcpflags 0x10<ACK>; tcp_input: Listen socket: Socket allocation failed due to limits or memory shortage, sending RST syncache.count is 0: net.inet.tcp.syncache.rst_on_sock_fail: 1 net.inet.tcp.syncache.rexmtlimit: 3 net.inet.tcp.syncache.hashsize: 512 net.inet.tcp.syncache.count: 0 net.inet.tcp.syncache.cachelimit: 15360 net.inet.tcp.syncache.bucketlimit: 30 and it seems that reason for the problem is that listen queue is overflown: Current listen queue sizes (qlen/incqlen/maxqlen) Proto Listen Local Address tcp4 193/0/128 10.2.3.1.80 I increased kern.ipc.somaxconn as temporary solution. netstat shows many (~193 - like the queue length) connections, mostly in CLOSED state (why aren't they purged?) I found some discussions about syncache changes in freebsd-net and other places but I'm not sure if my problem is known. Is there and reasoning and solution? regards -- Marcin Gryszkalis, PGP 0x9F183FA3 jabber jid:mg@fork.pl, gg:2532994 http://the.fork.pl
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