[Ecn-sane] osx ecn

Thu Aug 29 06:30:26 EDT 2019

On Wed, 28 Aug 2019, Dave Taht wrote:

> Could you hit it really hard with flent locally and see what happens?
>
> flent -H myownlanboxalsoatgige --te=upload_streams=200 tcp_nup
>
> and poll the netstat option.
>
> My guess is it just triggers on vms

I ran two concurrent sessions against two machines at home, each with 100 
streams (just to make sure I wasn't bottlenecking anything else apart from 
the iMac port).

TCP upload sum  :       473.50       464.35 Mbits/s         304

TCP upload sum  :       487.96       475.68 Mbits/s         304

My iMac has 30 hours uptime, so there's some other traffic in there as 
well.

en0: flags=8963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 
1500 index 7
 	eflags=400009c0<ACCEPT_RTADV,TXSTART,RXPOLL,ARPLL,FASTLN_ON>
 	options=10b<RXCSUM,TXCSUM,VLAN_HWTAGGING,AV>
...
 	nd6 options=201<PERFORMNUD,DAD>
 	media: autoselect (1000baseT <full-duplex>)
 	status: active
 	type: Ethernet
 	link quality: 100 (good)
 	state availability: 0 (true)
 	scheduler: FQ_CODEL
 	link rate: 1.00 Gbps
 	qosmarking enabled: yes mode: none
 	low power mode: disabled

tcp:
 	75183587 packets sent
 		59332651 data packets (3521003642 byte)
 		1387664 data packets (1738258246 bytes) retransmitted
 		0 resend initiated by MTU discovery
 		13380244 ack-only packets (765 delayed)
 		0 URG only packet
 		102 window probe packets
 		1072241 window update packets
 		23163 control packets
 		571945 data packets sent after flow control
 		61 challenge ACKs sent due to unexpected SYN
 		4 challenge ACKs sent due to unexpected RST
 		18314 checksummed in software
 			5196 segments (272795 bytes) over IPv4
 			13118 segments (1494655 bytes) over IPv6
 	45437408 packets received
 		20885349 acks (for 3523699640 byte)
 		2369692 duplicate acks
 		0 ack for unsent data
 		26469614 packets (3766989895 byte) received in-sequence
 		4634 completely duplicate packets (845184 bytes)
 		55 old duplicate packets
 		0 received packet dropped due to low memory
 		1 packet with some dup. data (9 bytes duped)
 		15064 out-of-order packets (21167582 bytes)
 		0 packet (0 byte) of data after window
 		0 window probe
 		300216 window update packets
 		808 packets recovered after loss
 		1584 packets received after close
 		4 bad resets
 		0 discarded for bad checksum
 		17245 checksummed in software
 			4655 segments (319983 bytes) over IPv4
 			12590 segments (1379223 bytes) over IPv6
 		0 discarded for bad header offset field
 		0 discarded because packet too short
 	13206 connection requests
 	83 connection accepts
 	15 bad connection attempts
 	0 listen queue overflow
 	12426 connections established (including accepts)
 	13687 connections closed (including 3494 drops)
 		2003 connections updated cached RTT on close
 		2003 connections updated cached RTT variance on close
 		283 connections updated cached ssthresh on close
 		2335 connections initialized RTT from route cache
 		2335 connections initialized RTT variance from route cache
 		291 connections initialized ssthresh from route cache
 	28 embryonic connections dropped
 	38165161 segments updated rtt (of 8172122 attempts)
 	60615 retransmit timeouts
 		123 connections dropped by rexmit timeout
 		0 connection dropped after retransmitting FIN
 		18 unnecessary packet retransmissionss
 	102 persist timeouts
 		0 connection dropped by persist timeout
 	18871 keepalive timeouts
 		18764 keepalive probes sent
 		20 connections dropped by keepalive
 	11710123 correct ACK header predictions
 	21748077 correct data packet header predictions
 	159802 SACK recovery episodes
 	984157 segment rexmits in SACK recovery episodes
 	1244806263 byte rexmits in SACK recovery episodes
 	3356069 SACK options (SACK blocks) received
 	16314 SACK options (SACK blocks) sent
 	0 SACK scoreboard overflow
 	0 LRO coalesced packet
 		0 time LRO flow table was full
 		0 collision in LRO flow table
 		0 time LRO coalesced 2 packets
 		0 time LRO coalesced 3 or 4 packets
 		0 time LRO coalesced 5 or more packets
 	321561 limited transmits done
 	1550 early retransmits done
 	9623 times cumulative ack advanced along with SACK
 	1069 probe timeouts
 		83 times retransmit timeout triggered after probe
 		0 time probe packets were sent for an interface
 		0 time couldn't send probe packets for an interface
 		13 times fast recovery after tail loss
 		186 times recovered last packet
 		96 SACK based rescue retransmits
 	8180 client connections attempted to negotiate ECN
 		3961 client connections successfully negotiated ECN
 		3489 times graceful fallback to Non-ECN connection
 		417 times lost ECN negotiating SYN, followed by retransmission
 		30 server connections attempted to negotiate ECN
 		30 server connections successfully negotiated ECN
 		0 time lost ECN negotiating SYN-ACK, followed by retransmission
 		23 times received congestion experienced (CE) notification
 		16 times CWR was sent in response to ECE
 		4998 times sent ECE notification
 		14 connections received CE atleast once
 		8 connections received ECE atleast once
 		308 connections using ECN have seen packet loss but no CE
 		2 connections using ECN have seen packet loss and CE
 		20 connections using ECN received CE but no packet loss
 		2 connections fell back to non-ECN due to SYN-loss
 		472 connections fell back to non-ECN due to reordering
 		0 connection fell back to non-ECN due to excessive CE-markings
 		0 connection fell back caused by connection drop due to RST
 		4 connections fell back due to drop after multiple retransmits
 		0 connection fell back due to RST after SYN
 	846 times packet reordering was detected on a connection
 		183836 times transmitted packets were reordered
 		145032 times fast recovery was delayed to handle reordering
 		183836 times retransmission was avoided by delaying recovery
 		0 retransmission not needed
 	22347 retransmissions due to tail loss
 	1146 times DSACK option was sent
 		8877 times DSACK option was received
 		97 times DSACK was disabled on a connection
 		761 times recovered from bad retransmission using DSACK
 		125 times ignored DSACK due to ack loss
 		94 times ignored old DSACK options
 	7 times PMTU Blackhole detection, size reverted
 	5 connections were dropped after long sleep
 	1 connection had stretch ack algorithm disabled
 	0 time a TFO-cookie has been announced
 	0 SYN with data and a valid TFO-cookie have been received
 	0 SYN with TFO-cookie-request received
 	0 time an invalid TFO-cookie has been received
 	0 time we requested a TFO-cookie
 		0 time the peer announced a TFO-cookie
 	0 time we combined SYN with data and a TFO-cookie
 		0 time our SYN with data has been acknowledged
 	0 time a connection-attempt with TFO fell back to regular TCP
 	0 time a TFO-connection blackhole'd
 	0 time a TFO-cookie we sent was wrong
 	0 time did not received a TFO-cookie we asked for
 	0 time TFO got disabled due to heuristicsn
 	0 time TFO got blackholed in the sending direction
 	0 time maximum segment size was changed to default
 	0 time maximum segment size was changed to medium
 	0 time maximum segment size was changed to low
 	842010 timer drifts less or equal to 1 ms
 	10837 timer drifts less or equal to 10 ms
 	2 timer drifts less or equal to 20 ms
 	5 timer drifts less or equal to 50 ms
 	3 timer drifts less or equal to 100 ms
 	6 timer drifts less or equal to 200 ms
 	0 timer drift less or equal to 500 ms
 	0 timer drift less or equal to 1000 ms
 	0 timer drift greater than to 1000 ms

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se