the performance of server written by libev, when the client just do "connect" and "close"

[fatmck]

at 2011-11-24 16:38, debuguo said:
> My test result is not only slow but also strange.
> 0.4 second at the most of the time, but sometimes it would be 3 sec.
>
I tried again, change loop count to a very big value, nowthe connect() 
blocked 3 sec sometimes.
tcpdump shows somethings:
011-11-24 17:29:47.749655 IP localhost.38363 > localhost.socks: Flags 
[F.], seq 3855382321, ack 3394797453, win 257, options [nop,nop,TS val 
28573710 ecr 28573651], length 0
2011-11-24 17:29:47.749702 IP localhost.38364 > localhost.socks: Flags 
[F.], seq 496093496, ack 3389089195, win 257, options [nop,nop,TS val 
28573710 ecr 28573651], length 0
2011-11-24 17:29:47.749894 IP localhost.socks > localhost.38363: Flags 
[R.], seq 1, ack 1, win 256, options [nop,nop,TS val 28573710 ecr 
28573710], length 0
2011-11-24 17:29:47.749987 IP localhost.socks > localhost.38364: Flags 
[R.], seq 1, ack 1, win 256, options [nop,nop,TS val 28573710 ecr 
28573710], length 0
2011-11-24 17:29:50.517717 IP localhost.38365 > localhost.socks: Flags 
[S], seq 4037677770, win 32792, options [mss 16396,sackOK,TS val 
28574402 ecr 0,nop,wscale 7], length 0
2011-11-24 17:29:50.517751 IP localhost.socks > localhost.38365: Flags 
[S.], seq 743007410, ack 4037677771, win 32768, options [mss 
16396,sackOK,TS val 28574402 ecr 28574402,nop,wscale 7], length 0
2011-11-24 17:29:50.517778 IP localhost.38365 > localhost.socks: Flags 
[.], ack 1, win 257, options [nop,nop,TS val 28574402 ecr 28574402], 
length 0
2011-11-24 17:30:02.464295 IP localhost.socks > localhost.38365: Flags 
[R.], seq 1, ack 1, win 256, options [nop,nop,TS val 28577388 ecr 
28574402], length 0

from 17:29:47 to 17:29:50, there is a 3 seconds gap. the connect() was 
invoked at 17:29:47, and its first SYN was sent out at 17:29:50. what 
happened in the 3 seconds? any one can explain this?