[Cake] cake flenter results round 1
Dave Taht
dave.taht at gmail.com
Mon Nov 27 12:33:12 EST 2017
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 at 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 at gmail.com> wrote:
>>
>>
>> On Nov 27, 2017, at 3:48 PM, Jonathan Morton <chromatix99 at 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 at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/cake
>>
>
>
> _______________________________________________
> Cake mailing list
> Cake at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake
>
--
Dave Täht
CEO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-669-226-2619
More information about the Cake
mailing list