[Cake] [PATCH 0/3] Add Common Applications Kept Enhanced (sch_cake) qdisc
Sebastian Moeller
moeller0 at gmx.de
Wed Nov 22 06:02:31 EST 2017
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 at 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 at 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 at 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 at 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 at 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 at 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 at 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
>
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