Re: [Cake] cake flenter results round 1

[Sebastian Moeller <moeller0@gmx.de>]

But 444.35 + 443.65 = 888, no?

> On Nov 27, 2017, at 18:33, Dave Taht <dave.taht@gmail.com> wrote:
> 
> georgios
> 
> the result you got was "fair", but you shoul have seen something
> closer to 900mbit than 400.
> 
> On Mon, Nov 27, 2017 at 8:17 AM, Georgios Amanakis <gamanakis@gmail.com> wrote:
>> Dear Pete,
>> 
>> I am trying to replicate the unfair behaviour you are seeing with
>> dual-{src,dst}host, albeit on different hardware and I am getting a fair
>> distribution. Hardware are Xeon E3-1220Lv2 (router), i3-3110M(Clients). All
>> running Archlinux, latest cake and patched iproute2-4.14.1, connected with
>> Gbit ethernet, TSO/GSO/GRO enabled.
>> 
>> Qdisc setup:
>> ----------------
>> Router:
>> qdisc cake 8003: dev ens4 root refcnt 2 bandwidth 900Mbit diffserv3
>> dual-dsthost rtt 100.0ms raw
>> 
>> Client A(kernel default):
>> qdisc fq_codel 0: dev eno2 root refcnt 2 limit 10240p flows 1024 quantum
>> 1514 target 5.0ms interval 100.0ms memory_limit 32Mb ecn
>> 
>> Client B (kernel default):
>> qdisc fq_codel 0: dev enp1s0 root refcnt 2 limit 10240p flows 1024 quantum
>> 1514 target 5.0ms interval 100.0ms memory_limit 32Mb ecn
>> ----------------
>> 
>> 
>> Cli:
>> ----------------
>> Router:
>> netserver &
>> 
>> Client A:
>> flent tcp_1down -H router
>> 
>> Client B:
>> flent tcp_12down -H router
>> ----------------
>> 
>> 
>> Results:
>> ----------------
>> Router:
>> qdisc cake 8003: root refcnt 2 bandwidth 900Mbit diffserv3 dual-dsthost rtt
>> 100.0ms raw
>> Sent 7126680117 bytes 4725904 pkt (dropped 10, overlimits 4439745 requeues
>> 0)
>> backlog 0b 0p requeues 0
>> memory used: 1224872b of 15140Kb
>> capacity estimate: 900Mbit
>>                 Bulk   Best Effort      Voice
>>  thresh     56250Kbit     900Mbit     225Mbit
>>  target         5.0ms       5.0ms       5.0ms
>>  interval     100.0ms     100.0ms     100.0ms
>>  pk_delay        14us       751us         7us
>>  av_delay         2us       642us         1us
>>  sp_delay         1us         1us         1us
>>  pkts          109948     4601651       14315
>>  bytes      160183242  6964893773     1618242
>>  way_inds           0       21009           0
>>  way_miss         160         188           5
>>  way_cols           0           0           0
>>  drops              0          10           0
>>  marks              0           0           0
>>  ack_drop           0           0           0
>>  sp_flows           0           1           1
>>  bk_flows           1           0           0
>>  un_flows           0           0           0
>>  max_len         7570       68130        1022
>> 
>> 
>> Client A:
>>                           avg       median          # data pts
>> Ping (ms) ICMP :         0.11         0.08 ms              350
>> TCP download   :       443.65       430.38 Mbits/s         301
>> 
>> 
>> Client B:
>>                             avg       median          # data pts
>> Ping (ms) ICMP   :         0.09         0.06 ms              350
>> TCP download avg :        37.03        35.87 Mbits/s         301
>> TCP download sum :       444.35       430.40 Mbits/s         301
>> TCP download::1  :        37.00        35.87 Mbits/s         301
>> TCP download::10 :        37.01        35.87 Mbits/s         301
>> TCP download::11 :        37.02        35.87 Mbits/s         301
>> TCP download::12 :        37.00        35.87 Mbits/s         301
>> TCP download::2  :        37.03        35.87 Mbits/s         301
>> TCP download::3  :        36.99        35.87 Mbits/s         301
>> TCP download::4  :        37.03        35.87 Mbits/s         301
>> TCP download::5  :        37.07        35.87 Mbits/s         301
>> TCP download::6  :        37.00        35.87 Mbits/s         301
>> TCP download::7  :        37.12        35.87 Mbits/s         301
>> TCP download::8  :        37.05        35.87 Mbits/s         301
>> TCP download::9  :        37.03        35.87 Mbits/s         301
>> ----------------
>> 
>> Does this suggest that it is indeed a problem of an underpowered CPU in your
>> case?
>> 
>> George
>> 
>> 
>> On Mon, Nov 27, 2017 at 10:53 AM, Pete Heist <peteheist@gmail.com> wrote:
>>> 
>>> 
>>> On Nov 27, 2017, at 3:48 PM, Jonathan Morton <chromatix99@gmail.com>
>>> wrote:
>>> 
>>> It's not at all obvious how we'd detect that.  Packets are staying in the
>>> queue for less time than the codel target, which is exactly what you'd get
>>> if you weren't saturated at all.
>>> 
>>> That makes complete sense when you put it that way. Cake has no way of
>>> knowing why the input rate is lower than expected, even if it’s part of the
>>> cause.
>>> 
>>> I don’t think flent can know this either. It can’t easily know the cause
>>> for its total output to be lower than expected.
>>> 
>>> All I know is, this is a common problem in deployments, particularly on
>>> low-end hardware like ER-Xs, that can be tricky for users to figure out.
>>> 
>>> I don’t even think monitoring CPU in general would work. The CPU could be
>>> high because it’s doing other calculations, but there’s still enough for
>>> cake at a low rate, and there’s no need to warn in that case. I’d be
>>> interested in any ideas on how to know this is happening in the system as a
>>> whole. So far, there are just various clues that one needs to piece together
>>> (no or few drops or marks, less total throughput that expected, high cpu
>>> without other external usage, etc). Then it needs to be proven with a test.
>>> 
>>> Anyway thanks, your clue was what I needed! I need to remember to review
>>> the qdisc stats when something unexpected happens.
>>> 
>>> _______________________________________________
>>> Cake mailing list
>>> Cake@lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/cake
>>> 
>> 
>> 
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> 
> 
> 
> -- 
> 
> Dave Täht
> CEO, TekLibre, LLC
> http://www.teklibre.com
> Tel: 1-669-226-2619
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