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From: Sebastian Moeller <moeller0@gmx.de>
To: "Dave Täht" <dave.taht@gmail.com>
Cc: cake@lists.bufferbloat.net
Subject: Re: [Cake] [PATCH 0/3] Add Common Applications Kept Enhanced (sch_cake) qdisc
Date: Wed, 22 Nov 2017 12:02:31 +0100	[thread overview]
Message-ID: <FDEBB87D-866B-4734-A26D-57AB3B13DDB7@gmx.de> (raw)
In-Reply-To: <1511309382-24060-1-git-send-email-dave.taht@gmail.com>

Hi All,

Tl;dr: Automatic accounting of the kernel added dev->hard_header_len seems currently broken at least in the cobalt branch...


as far as I can tell overhead accounting is still busted:


user@work-horse:~/CODE/sch_cake$ sudo ../tc-adv/tc/tc qdisc delete dev eth0 root; sudo ../tc-adv/tc/tc qdisc replace dev eth0 root cake raw overhead 5; ../tc-adv/tc/tc -s qdisc show dev eth0
sudo: unable to resolve host work-horse
sudo: unable to resolve host work-horse
qdisc cake 8014: root refcnt 6 unlimited diffserv3 triple-isolate rtt 100.0ms noatm overhead 19 via-ethernet total_overhead 19 hard_header_len 14 
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) 
 backlog 0b 0p requeues 0 
 memory used: 0b of 15140Kb
 capacity estimate: 0bit
                 Bulk   Best Effort      Voice
  thresh          0bit        0bit        0bit
  target         5.0ms       5.0ms       5.0ms
  interval     100.0ms     100.0ms      10.0ms
  pk_delay         0us         0us         0us
  av_delay         0us         0us         0us
  sp_delay         0us         0us         0us
  pkts               0           0           0
  bytes              0           0           0
  way_inds           0           0           0
  way_miss           0           0           0
  way_cols           0           0           0
  drops              0           0           0
  marks              0           0           0
  ack_drop           0           0           0
  sp_flows           0           0           0
  bk_flows           0           0           0
  un_flows           0           0           0
  max_len            0           0           0

user@work-horse:~/CODE/sch_cake$ sudo ../tc-adv/tc/tc qdisc delete dev eth0 root; sudo ../tc-adv/tc/tc qdisc replace dev eth0 root cake overhead 5; ../tc-adv/tc/tc -s qdisc show dev eth0
sudo: unable to resolve host work-horse
sudo: unable to resolve host work-horse
qdisc cake 8015: root refcnt 6 unlimited diffserv3 triple-isolate rtt 100.0ms raw total_overhead 14 hard_header_len 14 
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) 
 backlog 0b 0p requeues 0 
 memory used: 0b of 15140Kb
 capacity estimate: 0bit
                 Bulk   Best Effort      Voice
  thresh          0bit        0bit        0bit
  target         5.0ms       5.0ms       5.0ms
  interval     100.0ms     100.0ms      10.0ms
  pk_delay         0us         0us         0us
  av_delay         0us         0us         0us
  sp_delay         0us         0us         0us
  pkts               0           0           0
  bytes              0           0           0
  way_inds           0           0           0
  way_miss           0           0           0
  way_cols           0           0           0
  drops              0           0           0
  marks              0           0           0
  ack_drop           0           0           0
  sp_flows           0           0           0
  bk_flows           0           0           0
  un_flows           0           0           0
  max_len            0           0           0

user@work-horse:~/CODE/sch_cake$ 


The first seems okay, but the second should not have reported "raw" but rather total_overhead 5 hard_header_len 14 if I understand the intention of the overhead keyword correctly. This also affects the keywords like conservative:

user@work-horse:~/CODE/sch_cake$ sudo ../tc-adv/tc/tc qdisc delete dev eth0 root; sudo ../tc-adv/tc/tc qdisc replace dev eth0 root cake conservative; ../tc-adv/tc/tc -s qdisc show dev eth0
sudo: unable to resolve host work-horse
sudo: unable to resolve host work-horse
qdisc cake 8019: root refcnt 6 unlimited diffserv3 triple-isolate rtt 100.0ms atm overhead 14 via-ethernet total_overhead 14 hard_header_len 14 
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) 
 backlog 0b 0p requeues 0 
 memory used: 0b of 15140Kb
 capacity estimate: 0bit
                 Bulk   Best Effort      Voice
  thresh          0bit        0bit        0bit
  target         5.0ms       5.0ms       5.0ms
  interval     100.0ms     100.0ms      10.0ms
  pk_delay         0us         0us         0us
  av_delay         0us         0us         0us
  sp_delay         0us         0us         0us
  pkts               0           0           0
  bytes              0           0           0
  way_inds           0           0           0
  way_miss           0           0           0
  way_cols           0           0           0
  drops              0           0           0
  marks              0           0           0
  ack_drop           0           0           0
  sp_flows           0           0           0
  bk_flows           0           0           0
  un_flows           0           0           0
  max_len            0           0           0

user@work-horse:~/CODE/sch_cake$ sudo ../tc-adv/tc/tc qdisc delete dev eth0 root; sudo ../tc-adv/tc/tc qdisc replace dev eth0 root cake raw conservative; ../tc-adv/tc/tc -s qdisc show dev eth0
sudo: unable to resolve host work-horse
sudo: unable to resolve host work-horse
qdisc cake 801a: root refcnt 6 unlimited diffserv3 triple-isolate rtt 100.0ms atm overhead 62 via-ethernet total_overhead 62 hard_header_len 14 
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) 
 backlog 0b 0p requeues 0 
 memory used: 0b of 15140Kb
 capacity estimate: 0bit
                 Bulk   Best Effort      Voice
  thresh          0bit        0bit        0bit
  target         5.0ms       5.0ms       5.0ms
  interval     100.0ms     100.0ms      10.0ms
  pk_delay         0us         0us         0us
  av_delay         0us         0us         0us
  sp_delay         0us         0us         0us
  pkts               0           0           0
  bytes              0           0           0
  way_inds           0           0           0
  way_miss           0           0           0
  way_cols           0           0           0
  drops              0           0           0
  marks              0           0           0
  ack_drop           0           0           0
  sp_flows           0           0           0
  bk_flows           0           0           0
  un_flows           0           0           0
  max_len            0           0           0

user@work-horse:~/CODE/sch_cake$ 


So in other words currently the automatic accounting for the kernel added hard_header_len seems broken as the raw keyword disables that functionality. I will try to look deeper into that, but I guess with my limited C skills this might do more harm than good...

Best Regards
	Sebastian


> On Nov 22, 2017, at 01:09, Dave Taht <dave.taht@gmail.com> wrote:
> 
> sch_cake is intended to squeeze the most bandwidth and lowest latency out
> of even the slowest ISP links and routers, while presenting an API simple
> enough that even an ISP can configure it.
> 
> Example of use on an ISP uplink:
> 
> tc qdisc add dev eth0 cake bandwidth 20Mbit nat docsis ack-filter
> 
> Cake can also be used in unlimited mode to drive packets at the speed
> of the underlying link.
> 
> Cake is filled with:
> 
> * A hybrid Codel/Blue AQM algorithm, “Cobalt”, tied to an FQ_Codel
>  derived Flow Queuing system, which autoconfigures based on the bandwidth.
> * A unique "triple-isolate" mode (the default) which balances per-flow
>  and per-host flow FQ even through NAT.
> * An integral deficit based shaper with extensive dsl and docsis support
>  that can also be used in unlimited mode.
> * 8 way set associative queuing to reduce flow collisions to a minimum.
> * A reasonable interpretation of various diffserv latency/loss tradeoffs.
> * Support for washing diffserv for entering and exiting traffic.
> * Perfect support for interacting with Docsis 3.0 shapers.
> * Extensive support for DSL framing types.
> * (New) Support for ack filtering.
>  - 20 % better throughput at a 16x1 down/up ratio on the rrul test.
> * Extensive statistics for measuring loss, ecn markings, latency variation.
> 
> There are some features still considered experimental, notably the
> ingress_autorate bandwidth estimator and cobalt itself.
> 
> Various versions shipping have been available as an out of tree build for
> kernel versions going back to 3.10, as the embedded router world has been
> running a few years behind mainline Linux. A stable version has been
> generally available on lede-17.01 and later.
> 
> sch_cake replaces a combination of iptables, tc filter, htb and fq_codel in
> the sqm-scripts, with sane defaults and vastly easier configuration.
> 
> Cake's principal author is Jonathan Morton, with contributions from
> Kevin Darbyshire-Bryant, Toke Høiland-Jørgensen, Sebastian Moeller,
> Ryan Mounce, Dean Scarff, Guido Sarducci, Nils Andreas Svee, Dave Täht, and
> Loganaden Velvindron.
> 
> Dave Taht (3):
>  pkt_sched.h: add support for sch_cake API
>  Add Common Applications Kept Enhanced (sch_cake) qdisc
>  Add support for building the new cake qdisc
> 
> include/net/cobalt.h           |  152 +++
> include/uapi/linux/pkt_sched.h |   58 +
> net/sched/Kconfig              |   11 +
> net/sched/Makefile             |    1 +
> net/sched/sch_cake.c           | 2551 ++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 2773 insertions(+)
> create mode 100644 include/net/cobalt.h
> create mode 100644 net/sched/sch_cake.c
> 
> -- 
> 2.7.4
> 
> _______________________________________________
> Cake mailing list
> Cake@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake


  parent reply	other threads:[~2017-11-22 11:02 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-22  0:09 Dave Taht
2017-11-22  0:09 ` [Cake] [PATCH 1/3] pkt_sched.h: add support for sch_cake API Dave Taht
2017-11-22  0:55   ` Stephen Hemminger
2017-11-22  0:58     ` Dave Taht
2017-11-22 21:38       ` Stephen Hemminger
2017-11-22 22:35         ` Dave Taht
2017-11-24 13:33       ` Marcelo Ricardo Leitner
2017-11-24 20:53         ` Dave Taht
     [not found]     ` <CAJq5cE2j9o1vHhxEecHkKMUv65d-BxDvXNJXPWh=WHmXVqNUQA@mail.gmail.com>
     [not found]       ` <CAJq5cE36nijxKM6dpRPK2d8axZwf=35a8D=2oArPjusRKALLpA@mail.gmail.com>
2017-11-22  6:59         ` Jonathan Morton
2017-11-22  0:09 ` [Cake] [PATCH 2/3] Add Common Applications Kept Enhanced (sch_cake) qdisc Dave Taht
2017-11-22  0:55   ` Dave Taht
2017-11-22  2:33     ` Ryan Mounce
2017-11-22  7:46     ` Toke Høiland-Jørgensen
2017-11-22  0:09 ` [Cake] [PATCH 3/3] Add support for building the new cake qdisc Dave Taht
2017-11-22 11:02 ` Sebastian Moeller [this message]
2017-11-22 18:03   ` [Cake] [PATCH 0/3] Add Common Applications Kept Enhanced (sch_cake) qdisc Dave Taht
2017-11-23  7:54     ` Sebastian Moeller
2017-11-23 21:43     ` Sebastian Moeller
2017-11-23 22:02       ` Sebastian Moeller
2017-11-23 22:20         ` Sebastian Moeller
2017-11-23 22:26           ` Dave Taht

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