FreeBSD 7.0-RC1 syncache problems under high load

[s3raphi]

I am running web polygraph against a FreeBSD7.0-RC1 squid server and
experiencing problems. I have run the same test against the same hardware on
FreeBSD 6.1 without issue. This seems to be specific to FreeBSD 7. 
The problem is related to the number of client connections:
250 Clients - runs great.
500 Clients- scores well in polygraph, but does have a few errored requests
750-2000 Clients - Error rate spikes way up and performance takes a
nosedive. 

I turned on TCP debugging on the server and found lots of this: 

Jan 19 18:12:46 FlashCache kernel: TCP: [192.168.200.2]:60525 to
[192.168.200.1]:8080 tcpflags 0x10<ACK>; syncache_expand: Segment failed
SYNCOOKIE authentication, segment rejected (probably spoofed)
Jan 19 18:12:46 FlashCache kernel: TCP: [192.168.200.2]:50115 to
[192.168.200.1]:8080 tcpflags 0x2<SYN>; syncache_add: Received duplicate
SYN, resetting timer and retransmitting SYN|ACK
Jan 19 18:12:47 FlashCache kernel: TCP: [192.168.200.2]:50132 to
[192.168.200.1]:8080; syncache_timer: Response timeout, retransmitting (1)
SYN|ACK
Jan 19 18:12:48 FlashCache kernel: TCP: [192.168.200.2]:50132 to
[192.168.200.1]:8080 tcpflags 0x2<SYN>; syncache_add: Received duplicate
SYN, resetting timer and retransmitting SYN|ACK
Jan 19 18:12:48 FlashCache kernel: TCP: [192.168.200.2]:50138 to
[192.168.200.1]:8080 tcpflags 0x2<SYN>; syncache_add: Received duplicate
SYN, resetting timer and retransmitting SYN|ACK
Jan 19 18:12:48 FlashCache kernel: TCP: [192.168.200.2]:50144 to
[192.168.200.1]:8080 tcpflags 0x2<SYN>; syncache_add: Received duplicate
SYN, resetting timer and retransmitting SYN|ACK
Jan 19 18:12:49 FlashCache kernel: TCP: [192.168.200.2]:50169 to
[192.168.200.1]:8080 tcpflags 0x2<SYN>; syncache_add: Received duplicate
SYN, resetting timer and retransmitting SYN|ACK
Jan 19 18:12:49 FlashCache kernel: TCP: [192.168.200.2]:50170 to
[192.168.200.1]:8080 tcpflags 0x2<SYN>; syncache_add: Received duplicate
SYN, resetting timer and retransmitting SYN|ACK
Jan 19 18:12:52 FlashCache kernel: TCP: [192.168.200.2]:50203 to
[192.168.200.1]:8080 tcpflags 0x2<SYN>; syncache_add: Received duplicate
SYN, resetting timer and retransmitting SYN|ACK
Jan 19 18:12:52 FlashCache kernel: TCP: [192.168.200.2]:50167 to
[192.168.200.1]:8080; syncache_timer: Response timeout, retransmitting (1)
SYN|ACK
Jan 19 18:12:52 FlashCache kernel: TCP: [192.168.200.2]:50166 to
[192.168.200.1]:8080; syncache_timer: Response timeout, retransmitting (1)
SYN|ACK

This looks similar to something that has already been fixed in July. I am
assuming that the July fix is included in RC1?
http://www.nabble.com/FreeBSD-7-TCP-syncache-fix%3A-request-for-testers-to11515217.html#a11776616

I am using a generic kernel, and have this problem on both ethernet cards I
have tested with(nfe and bge)

These two machines were connected by a switch, but are now directly
connected and have the same problem regardless.
-- 
View this message in context: http://www.nabble.com/FreeBSD-7.0-RC1-syncache-problems-under-high-load-tp14977783p14977783.html
Sent from the freebsd-questions mailing list archive at Nabble.com.