Playing with fq_codel in 2.4

dtaht

@strangegopher sch_cake is an advanced version of "sqm" with an integral shaper and a zillion other features that we worked on for the last 5 years. It's now in linux 4.19. With all the "second system syndrome" ideas in it, it's about twice as cpu intensive as htb + fq_codel. :(. There's a lot in cake I don't like. And I'm one of the authors! I wanted something faster and more elegant.

details:

https://www.bufferbloat.net/projects/codel/wiki/CakeTechnical/
https://lwn.net/Articles/758353/

It's really mostly targetted at sub 20Mbit uplinks but we have got it to 50Gbit on heavy duty hw.

But: some of the good ideas are amazing - per host fq, ack-filtering, robust classificaton, and easy one line setup. Specific to your question was how by matching the docsis or dsl framing overhead you can get to ~100% of your outbound line rate - ripping that idea out of cake and making it work generically in freebsd's limiters would let outbound match the isp rate, as I said. cake is dual bsd/gpl licensed for this reason, but unlike fq_codel, I'd kind of prefer people lift the best ideas out of it and use them rather than slavishly copy the code.

some details about how you could make freebsd's limiter obey docsis framing on this thread here:

https://github.com/dtaht/sch_cake/issues/48

dtaht

someone try this at 100mbit+ speeds:

hw.igb.max_interrupt_rate="128000"

I don't know where to increase the rx ring, in linux we use "ethtool". Probably these?

hw.igb.rxd="4096"
hw.igb.txd="4096"

dtaht

for the record, this is cake:

root@office:~# tc -s qdisc show dev eth0
qdisc cake 8010: root refcnt 9 bandwidth 9Mbit diffserv3 triple-isolate nat nowash ack-filter split-gso rtt 100.0ms noatm overhead 18 mpu 64 
 Sent 3823129438 bytes 27251388 pkt (dropped 2316876, overlimits 34025373 requeues 343) 
 backlog 0b 0p requeues 343
 memory used: 313464b of 4Mb
 capacity estimate: 9Mbit
 min/max network layer size:           28 /    1500
 min/max overhead-adjusted size:       64 /    1518
 average network hdr offset:           14

                   Bulk  Best Effort        Voice
  thresh      562496bit        9Mbit     2250Kbit
  target         32.3ms        5.0ms        8.1ms
  interval      127.3ms      100.0ms      103.1ms
  pk_delay          0us        1.8ms         27us
  av_delay          0us        132us          6us
  sp_delay          0us          4us          4us
  backlog            0b           0b           0b
  pkts                0     29491122        77142
  bytes               0   3971468896     11505073
  way_inds            0      1290904         1214
  way_miss            0       474687         3673
  way_cols            0            0            0
  drops               0         1029            0
  marks               0            4            0
  ack_drop            0      2315847            0
  sp_flows            0            2            1
  bk_flows            0            2            0
  un_flows            0            0            0
  max_len             0        28766         1198
  quantum           300          300          300

I have a feeling y'all here like fiddling with classification and rules and so on, but
sometimes it's nice to just type

tc qdisc add dev eth0 root cake bandwidth 9mbit nat docsis ack-filter

and be done with it.

dtaht

note: I have $dayjob and sailing tomorrow. don't expect replies.I sure hope the icmp issue is nailed....

Happy debloating!

uptownVagrant

@dtaht

Here is the Atom C2758 doing 500mbit.

Here are the customized sysctl values:

net.inet.tcp.tso="0"
net.inet.tcp.lro="0"
dev.igb.0.fc="0"
dev.igb.1.fc="0"
dev.igb.2.fc="0"
dev.igb.3.fc="0"
dev.igb.0.eee_disabled="1"
dev.igb.1.eee_disabled="1"
dev.igb.2.eee_disabled="1"
dev.igb.3.eee_disabled="1"
hw.igb.rxd="4096"
hw.igb.txd="4096"
hw.igb.rx_process_limit="-1"
hw.igb.tx_process_limit="-1"
hw.igb.num_queues="8"
hw.igb.max_interrupt_rate="128000"
net.inet.tcp.hostcache.cachelimit="0"
net.inet.tcp.syncache.bucketlimit="100"
net.inet.tcp.syncache.hashsize="1024"

Here is 500mbit without ECN.

0_1538717644506_8e4e8f5b-9b34-4942-8f2e-072a3b048de1-image.png
0_1538717701396_rrul-2018-10-04T221358.673929.UptownVagrant_C2758_pfSense2_4_4_500Mbit.flent.gz

Here is 500mbit with end-to-end ECN enabled.

0_1538717673989_6e870160-9e6f-48e2-bc17-6ef0eca87fdc-image.png
0_1538717713043_rrul-2018-10-04T222431.621780.UptownVagrant_C2758_pfSense2_4_4_500Mbit_ECN.flent.gz

I have confirmed that disabling NAT removes the dropped icmp behaviour, traceroute loops, when limiters are used on an interface with NAT.

zwck

@dtaht

I switched to a server closer and upped the computing power :D

This is shaped to 800Mbps
1_1538719369675_rrul-2018-10-05T075404.739377.zwck-shaper_on_800Mbit.flent.gz 0_1538719369675_RRUL_Test001_bufferbloat-shaper_on_800Mbit.png

dtaht

@uptownvagrant awesome. Is there a path for y'all to report this problem back to netgate and the freebsd devs? I'm totally over my head there. With nat you are using more cpu of course and there may be more variables worth tuning for more resources, the gc interval, and so on.

Your .5ms of smoothish jitter is a little puzzling but I can live with it. freebsd does not have sub 1ms timestamp resolution so perhaps that's it. What's 500usec between friends? :)

another nice flent thing is the ability to do comparison plots. The ecn result has smoother throughput.

0_1538719774640_smoother_ecn.4.4_500Mbit.png

dtaht

@zwck you sure you shaped the dl to 800mbits? 'cause that's 28mbit. could also be your server or client has a fifo on it too, fq_codel or sch_fq on linux help with bidir tests a lot, also. or it could be flent-london... (flent's tcp_download test? the rrul test is extreme you can drill down with simpler tests)

(I thought you might be near england! It's really weird that I have such a grasp of worldwide rtts)

zwck

@dtaht

Hi and goodmoring. (for me at least)

Also i included @uptownVagrant 's tuning as we have more or less the same pfsense setup :D
Sorry that such a newbie, such as i, is posting here too, sadly the topic is far from my expertise.

ipfw sched show
10000: 500.000 Mbit/s    0 ms burst 0
q75536  50 sl. 0 flows (1 buckets) sched 10000 weight 0 lmax 0 pri 0 droptail
 sched 10000 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10000
BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp
  0 ip           0.0.0.0/0             0.0.0.0/0        3      144  0    0   0
10001: 500.000 Mbit/s    0 ms burst 0
q75537  50 sl. 0 flows (1 buckets) sched 10001 weight 0 lmax 0 pri 0 droptail
 sched 10001 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10001
  0 ip           0.0.0.0/0             0.0.0.0/0        6      540  0    0   0

and rrd 1_1538720733109_RRUL_Test001_bufferbloat-shaper_on_500Mbit.png

0_1538720733109_rrul-2018-10-05T081320.821182.zwck-shaper_on_500Mbit.flent.gz

dtaht

It;s awesome to have more folk doing bidir network stress testing with flent. nobody in product marketing wants you to do that.

@zwck ok, I rebooted the box in london (it had a tcp tweak i didn't like), It should be back up in a minute. It looks to me though you just peak out at 1gbit total, though, on this hw...)

dtaht

@zwck said in Playing with fq_codel in 2.4:

burst 0

Is there a way to tune the "burst" value in the limiter above? It's nice to see the dscp values actually being respected e2e here also. that never happens.

dtaht

btw, the rrul test does not account for tcp ack traffic. When i see ~480Mbit of perfect fq_codeled bandwidth at 500mbit, it's a good assumption the remaining ~20mbit was acks as there's about a 20x1 ratio there

dtaht

@zwck said in Playing with fq_codel in 2.4:

ipfw sched show

during a test would be interesting.

zwck

@dtaht

speedtest

aftre london rebooted :D

1_1538721917996_rrul-2018-10-05T083834.071452.zwck-shaper_on_500Mbit.flent.gz

0_1538721917996_RRUL_Test001_bufferbloat-shaper_on_500Mbit.png

admin@pfsense:~ # ipfw sched show
10000: 500.000 Mbit/s    0 ms burst 0
q75536  50 sl. 0 flows (1 buckets) sched 10000 weight 0 lmax 0 pri 0 droptail
 sched 10000 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10000
BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp
  0 ip           0.0.0.0/0             0.0.0.0/0     2357  2546546  0    0   0
10001: 500.000 Mbit/s    0 ms burst 0
q75537  50 sl. 0 flows (1 buckets) sched 10001 weight 0 lmax 0 pri 0 droptail
 sched 10001 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10001
  0 ip           0.0.0.0/0             0.0.0.0/0     306719 434714257 106 154656   7
admin@pfsense:~ # ipfw sched show
10000: 500.000 Mbit/s    0 ms burst 0
q75536  50 sl. 0 flows (1 buckets) sched 10000 weight 0 lmax 0 pri 0 droptail
 sched 10000 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10000
BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp
  0 ip           0.0.0.0/0             0.0.0.0/0     4507  5174782  8 6208   0
10001: 500.000 Mbit/s    0 ms burst 0
q75537  50 sl. 0 flows (1 buckets) sched 10001 weight 0 lmax 0 pri 0 droptail
 sched 10001 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10001
  0 ip           0.0.0.0/0             0.0.0.0/0     362125 513262875 133 199500   7
admin@pfsense:~ # ipfw sched show
10000: 500.000 Mbit/s    0 ms burst 0
q75536  50 sl. 0 flows (1 buckets) sched 10000 weight 0 lmax 0 pri 0 droptail
 sched 10000 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10000
BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp
  0 ip           0.0.0.0/0             0.0.0.0/0       46    61760  0    0   0
10001: 500.000 Mbit/s    0 ms burst 0
q75537  50 sl. 0 flows (1 buckets) sched 10001 weight 0 lmax 0 pri 0 droptail
 sched 10001 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10001
  0 ip           0.0.0.0/0             0.0.0.0/0     5427  7667181  0    0   0
admin@pfsense:~ # ipfw sched show
10000: 500.000 Mbit/s    0 ms burst 0
q75536  50 sl. 0 flows (1 buckets) sched 10000 weight 0 lmax 0 pri 0 droptail
 sched 10000 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10000
BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp
  0 ip           0.0.0.0/0             0.0.0.0/0     3294  3669449 14 10864   0
10001: 500.000 Mbit/s    0 ms burst 0
q75537  50 sl. 0 flows (1 buckets) sched 10001 weight 0 lmax 0 pri 0 droptail
 sched 10001 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10001
  0 ip           0.0.0.0/0             0.0.0.0/0     90572 128064966 100 147104   1

dtaht

well, the 500mbit results are awesome. there's 4 bursty drop episodes on the download that could be coming from anywhere for any cause - my box, yours, linode's shapers, the path, cosmic radiation.

try a rrul_be test to see if you get that big bursy drop. It's midnight here. I'm fading

zwck

@dtaht Thanks for the awesome help. It's in am's over here and i need to get to work. I have to read your flent documentation properly, enjoy your sailing trip.

dtaht

I don't have much insight into that drop but the recovery pattern looks normal

0_1538722775830_bigdrop.4.4_500Mbit_ECN.png

I dont have bbr on that box so can't try that, and is not the miracle of the juniper bushes enough? 800mbit still weird, though?

this also show's diffserv cs1 being respected.

.... you normally shouldn't see all 3 flows dropping a packet at the same time, just one (and you'd see, as in earlier in the test the flows trading bandwidth back and forth in the tcp sawtooth pattern). with 3 simultaneous drops they all cut their bandwidth in half and utilization is lowered while they recover.

dtaht

This post is deleted!

dtaht

have a song: https://plus.google.com/u/0/107942175615993706558/posts/UtcLY2W9NXy

zwck

@dtaht have fun

10000: 800.000 Mbit/s    0 ms burst 0
q75536  50 sl. 0 flows (1 buckets) sched 10000 weight 0 lmax 0 pri 0 droptail
 sched 10000 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10000
BKT Prot ___Source IP/port____ ____Dest. IP/port____ Tot_pkt/bytes Pkt/Byte Drp
  0 ip           0.0.0.0/0             0.0.0.0/0     3780  4324863  0    0   0
10001: 800.000 Mbit/s    0 ms burst 0
q75537  50 sl. 0 flows (1 buckets) sched 10001 weight 0 lmax 0 pri 0 droptail
 sched 10001 type FQ_CODEL flags 0x0 512 buckets 1 active
 FQ_CODEL target 5ms interval 60ms quantum 1514 limit 10240 flows 1024 ECN
   Children flowsets: 10001
  0 ip           0.0.0.0/0             0.0.0.0/0     107473 153093543 201 297156   1

1_1538723446600_RRUL_Test001_bufferbloat-shaper_on_800Mbit.png

0_1538723446599_rrul-2018-10-05T090400.526623.zwck-shaper_on_800Mbit.flent.gz