Date: Tue, 4 Jun 2002 23:00:22 -0400 (EDT) From: Nguyen-Tuong Long Le <le@cs.unc.edu> To: freebsd-net@FreeBSD.ORG Cc: Nguyen-Tuong Long Le <le@cs.unc.edu> Subject: Re: Problem with SYN cache in FreeBSD 4.5 Message-ID: <Pine.GSO.4.10.10206042250540.19770-100000@capefear.cs.unc.edu> In-Reply-To: <20020604194538.J42854-100000@patrocles.silby.com>
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Hi,
On Tue, 4 Jun 2002, Mike Silbersack wrote:
>
> On Tue, 4 Jun 2002, jayanth wrote:
>
> > Can you dump the output of netstat -s -p tcp ?
> > Checking for listen queue overflows and syncache bucket overflows.
> >
> > jayanth
>
Here is the output of "netstat -s -p tcp".
tcp:
264136 packets sent
104124 data packets (127937368 bytes)
286 data packets (344573 bytes) retransmitted
0 resends initiated by MTU discovery
147203 ack-only packets (127 delayed)
0 URG only packets
2 window probe packets
3 window update packets
12518 control packets
747675 packets received
85799 acks (for 127931017 bytes)
3247 duplicate acks
0 acks for unsent data
83750 packets (11689418 bytes) received in-sequence
89 completely duplicate packets (5552 bytes)
0 old duplicate packets
0 packets with some dup. data (0 bytes duped)
2 out-of-order packets (796 bytes)
0 packets (0 bytes) of data after window
0 window probes
30312 window update packets
0 packets received after close
0 discarded for bad checksums
0 discarded for bad header offset fields
0 discarded because packet too short
14 connection requests
17243 connection accepts
372055 bad connection attempts
87501 listen queue overflows
17257 connections established (including accepts)
16695 connections closed (including 1 drop)
830 connections updated cached RTT on close
830 connections updated cached RTT variance on close
178 connections updated cached ssthresh on close
0 embryonic connections dropped
85798 segments updated rtt (of 50455 attempts)
201 retransmit timeouts
0 connections dropped by rexmit timeout
0 persist timeouts
0 connections dropped by persist timeout
0 keepalive timeouts
0 keepalive probes sent
0 connections dropped by keepalive
376 correct ACK header predictions
61279 correct data packet header predictions
104747 syncache entries added
189 retransmitted
285 dupsyn
0 dropped
17243 completed
0 bucket overflow
0 cache overflow
3 reset
0 stale
87501 aborted
0 badack
0 unreach
0 zone failures
0 cookies sent
0 cookies received
> And "netstat -La" too, please. I'm interested in if you're accepting
> sockets fast enough.
Here is the output of "netstat -La"
Current listen queue sizes (qlen/incqlen/maxqlen)
Proto Listen Local Address
tcp4 3/0/8192 *.6789
I wonder why the listen queue overflows when there are so few
connections in the queue. The number of listen queue overflows
is equal to the number of syncache aborts. Is it a coincidence
or are they related?
Thanks,
-- long
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