misc/173859: Low throughput on intercontinental connections

[Marc Peters]

The following reply was made to PR misc/173859; it has been noted by GNATS.

From: Marc Peters <marc at mpeters.org>
To: bug-followup at FreeBSD.org, Marc Peters <marc at mpeters.org>
Cc:  
Subject: Re: misc/173859: Low throughput on intercontinental connections
Date: Fri, 23 Nov 2012 16:03:36 +0100

 As Adrian Chadd requested, the output of netstat -sp tcp before and
 after sending/receiving a 100MB testfile (created with dd if=/dev/random
 of=testfile bs=5M count=20 and copied by scp):
 
 
 sending host, before:
 
 tcp:
 	4 packets sent
 		4 data packets (2576 bytes)
 		0 data packets (0 bytes) retransmitted
 		0 data packets unnecessarily retransmitted
 		0 resends initiated by MTU discovery
 		0 ack-only packets (0 delayed)
 		0 URG only packets
 		0 window probe packets
 		0 window update packets
 		0 control packets
 	4 packets received
 		4 acks (for 2576 bytes)
 		0 duplicate acks
 		0 acks for unsent data
 		0 packets (0 bytes) received in-sequence
 		0 completely duplicate packets (0 bytes)
 		0 old duplicate packets
 		0 packets with some dup. data (0 bytes duped)
 		0 out-of-order packets (0 bytes)
 		0 packets (0 bytes) of data after window
 		0 window probes
 		0 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
 		0 discarded due to memory problems
 	0 connection requests
 	0 connection accepts
 	0 bad connection attempts
 	0 listen queue overflows
 	0 ignored RSTs in the windows
 	0 connections established (including accepts)
 	0 connections closed (including 0 drops)
 		0 connections updated cached RTT on close
 		0 connections updated cached RTT variance on close
 		0 connections updated cached ssthresh on close
 	0 embryonic connections dropped
 	4 segments updated rtt (of 1 attempt)
 	0 retransmit timeouts
 		0 connections dropped by rexmit timeout
 	0 persist timeouts
 		0 connections dropped by persist timeout
 	0 Connections (fin_wait_2) dropped because of timeout
 	0 keepalive timeouts
 		0 keepalive probes sent
 		0 connections dropped by keepalive
 	4 correct ACK header predictions
 	0 correct data packet header predictions
 	0 syncache entries added
 		0 retransmitted
 		0 dupsyn
 		0 dropped
 		0 completed
 		0 bucket overflow
 		0 cache overflow
 		0 reset
 		0 stale
 		0 aborted
 		0 badack
 		0 unreach
 		0 zone failures
 	0 cookies sent
 	0 cookies received
 	0 hostcache entries added
 		0 bucket overflow
 	0 SACK recovery episodes
 	0 segment rexmits in SACK recovery episodes
 	0 byte rexmits in SACK recovery episodes
 	0 SACK options (SACK blocks) received
 	0 SACK options (SACK blocks) sent
 	0 SACK scoreboard overflow
 	0 packets with ECN CE bit set
 	0 packets with ECN ECT(0) bit set
 	0 packets with ECN ECT(1) bit set
 	0 successful ECN handshakes
 	0 times ECN reduced the congestion window
 
 sending host, after:
 tcp:
 	45248 packets sent
 		44477 data packets (105036153 bytes)
 		6 data packets (7548 bytes) retransmitted
 		0 data packets unnecessarily retransmitted
 		0 resends initiated by MTU discovery
 		763 ack-only packets (0 delayed)
 		0 URG only packets
 		0 window probe packets
 		0 window update packets
 		2 control packets
 	63733 packets received
 		44518 acks (for 105036057 bytes)
 		823 duplicate acks
 		0 acks for unsent data
 		817 packets (40385 bytes) received in-sequence
 		169 completely duplicate packets (192 bytes)
 		132 old duplicate packets
 		0 packets with some dup. data (0 bytes duped)
 		12 out-of-order packets (1056 bytes)
 		0 packets (0 bytes) of data after window
 		0 window probes
 		14627 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
 		0 discarded due to memory problems
 	1 connection request
 	0 connection accepts
 	0 bad connection attempts
 	0 listen queue overflows
 	0 ignored RSTs in the windows
 	1 connection established (including accepts)
 	0 connections closed (including 0 drops)
 		0 connections updated cached RTT on close
 		0 connections updated cached RTT variance on close
 		0 connections updated cached ssthresh on close
 	0 embryonic connections dropped
 	44518 segments updated rtt (of 44248 attempts)
 	0 retransmit timeouts
 		0 connections dropped by rexmit timeout
 	0 persist timeouts
 		0 connections dropped by persist timeout
 	0 Connections (fin_wait_2) dropped because of timeout
 	0 keepalive timeouts
 		0 keepalive probes sent
 		0 connections dropped by keepalive
 	1245 correct ACK header predictions
 	670 correct data packet header predictions
 	0 syncache entries added
 		0 retransmitted
 		0 dupsyn
 		0 dropped
 		0 completed
 		0 bucket overflow
 		0 cache overflow
 		0 reset
 		0 stale
 		0 aborted
 		0 badack
 		0 unreach
 		0 zone failures
 	0 cookies sent
 	0 cookies received
 	0 hostcache entries added
 		0 bucket overflow
 	0 SACK recovery episodes
 	0 segment rexmits in SACK recovery episodes
 	0 byte rexmits in SACK recovery episodes
 	0 SACK options (SACK blocks) received
 	0 SACK options (SACK blocks) sent
 	0 SACK scoreboard overflow
 	0 packets with ECN CE bit set
 	0 packets with ECN ECT(0) bit set
 	0 packets with ECN ECT(1) bit set
 	0 successful ECN handshakes
 	0 times ECN reduced the congestion window
 
 receiving host, before:
 tcp:
 	8 packets sent
 		8 data packets (2768 bytes)
 		0 data packets (0 bytes) retransmitted
 		0 data packets unnecessarily retransmitted
 		0 resends initiated by MTU discovery
 		0 ack-only packets (0 delayed)
 		0 URG only packets
 		0 window probe packets
 		0 window update packets
 		0 control packets
 	1 packet received
 		1 ack (for 48 bytes)
 		0 duplicate acks
 		0 acks for unsent data
 		0 packets (0 bytes) received in-sequence
 		0 completely duplicate packets (0 bytes)
 		0 old duplicate packets
 		0 packets with some dup. data (0 bytes duped)
 		0 out-of-order packets (0 bytes)
 		0 packets (0 bytes) of data after window
 		0 window probes
 		0 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
 		0 discarded due to memory problems
 	0 connection requests
 	0 connection accepts
 	0 bad connection attempts
 	0 listen queue overflows
 	0 ignored RSTs in the windows
 	0 connections established (including accepts)
 	0 connections closed (including 0 drops)
 		0 connections updated cached RTT on close
 		0 connections updated cached RTT variance on close
 		0 connections updated cached ssthresh on close
 	0 embryonic connections dropped
 	1 segment updated rtt (of 0 attempts)
 	0 retransmit timeouts
 		0 connections dropped by rexmit timeout
 	0 persist timeouts
 		0 connections dropped by persist timeout
 	0 Connections (fin_wait_2) dropped because of timeout
 	0 keepalive timeouts
 		0 keepalive probes sent
 		0 connections dropped by keepalive
 	1 correct ACK header prediction
 	0 correct data packet header predictions
 	0 syncache entries added
 		0 retransmitted
 		0 dupsyn
 		0 dropped
 		0 completed
 		0 bucket overflow
 		0 cache overflow
 		0 reset
 		0 stale
 		0 aborted
 		0 badack
 		0 unreach
 		0 zone failures
 	0 cookies sent
 	0 cookies received
 	0 hostcache entries added
 		0 bucket overflow
 	0 SACK recovery episodes
 	0 segment rexmits in SACK recovery episodes
 	0 byte rexmits in SACK recovery episodes
 	0 SACK options (SACK blocks) received
 	0 SACK options (SACK blocks) sent
 	0 SACK scoreboard overflow
 	0 packets with ECN CE bit set
 	0 packets with ECN ECT(0) bit set
 	0 packets with ECN ECT(1) bit set
 	0 successful ECN handshakes
 	0 times ECN reduced the congestion window
 
 receiving host, after:
 tcp:
 	63748 packets sent
 		929 data packets (58374 bytes)
 		4 data packets (768 bytes) retransmitted
 		0 data packets unnecessarily retransmitted
 		0 resends initiated by MTU discovery
 		37099 ack-only packets (21 delayed)
 		0 URG only packets
 		0 window probe packets
 		25713 window update packets
 		3 control packets
 	84665 packets received
 		922 acks (for 57523 bytes)
 		27 duplicate acks
 		0 acks for unsent data
 		83191 packets (104368795 bytes) received in-sequence
 		0 completely duplicate packets (0 bytes)
 		0 old duplicate packets
 		0 packets with some dup. data (0 bytes duped)
 		523 out-of-order packets (653588 bytes)
 		0 packets (0 bytes) of data after window
 		0 window probes
 		1 window update packet
 		0 packets received after close
 		0 discarded for bad checksums
 		0 discarded for bad header offset fields
 		0 discarded because packet too short
 		0 discarded due to memory problems
 	0 connection requests
 	3 connection accepts
 	0 bad connection attempts
 	0 listen queue overflows
 	1 ignored RSTs in the window
 	3 connections established (including accepts)
 	66 connections closed (including 0 drops)
 		1 connection updated cached RTT on close
 		1 connection updated cached RTT variance on close
 		1 connection updated cached ssthresh on close
 	0 embryonic connections dropped
 	922 segments updated rtt (of 812 attempts)
 	0 retransmit timeouts
 		0 connections dropped by rexmit timeout
 	0 persist timeouts
 		0 connections dropped by persist timeout
 	0 Connections (fin_wait_2) dropped because of timeout
 	0 keepalive timeouts
 		0 keepalive probes sent
 		0 connections dropped by keepalive
 	786 correct ACK header predictions
 	83095 correct data packet header predictions
 	3 syncache entries added
 		0 retransmitted
 		0 dupsyn
 		0 dropped
 		3 completed
 		0 bucket overflow
 		0 cache overflow
 		0 reset
 		0 stale
 		0 aborted
 		0 badack
 		0 unreach
 		0 zone failures
 	3 cookies sent
 	0 cookies received
 	0 hostcache entries added
 		0 bucket overflow
 	0 SACK recovery episodes
 	0 segment rexmits in SACK recovery episodes
 	0 byte rexmits in SACK recovery episodes
 	0 SACK options (SACK blocks) received
 	0 SACK options (SACK blocks) sent
 	0 SACK scoreboard overflow
 	0 packets with ECN CE bit set
 	0 packets with ECN ECT(0) bit set
 	0 packets with ECN ECT(1) bit set
 	0 successful ECN handshakes
 	0 times ECN reduced the congestion window