>> I certainly am thankful for your work, and believe you deserve $CAKE
>> and $BEVERAGE, I am also leaf to believe 'the cake is a lie'
>> https://m.youtube.com/watch?v=qdrs3gr_GAs ;)
>
> Haha, yes, of course I am aware that the cake really is a lie. Which
> makes us in league with GLADOS, I
Thank you for the review! A few comments below, I'll fix the rest.
> [...]
>
> So sch_cake doesn't accept normal tc filters? Is this intentional?
> If so, why?
For two reasons:
- The two-level scheduling used in CAKE (tins / diffserv classes, and
flow hashing) does not map in an obvious way
The ACK filter is an optional feature of CAKE which is designed to improve
performance on links with very asymmetrical rate limits. On such links
(which are unfortunately quite prevalent, especially for DSL and cable
subscribers), the downstream throughput can be limited by the number of
ACKs
When CAKE is deployed on a gateway that also performs NAT (which is a
common deployment mode), the host fairness mechanism cannot distinguish
internal hosts from each other, and so fails to work correctly.
To fix this, we add an optional NAT awareness mode, which will query the
kernel conntrack
This adds support for DiffServ-based priority queueing to CAKE. If the
shaper is in use, each priority tier gets its own virtual clock, which
limits that tier's rate to a fraction of the overall shaped rate, to
discourage trying to game the priority mechanism.
CAKE defaults to a simple,
sch_cake targets the home router use case and is intended to squeeze the
most bandwidth and 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 a cable ISP uplink:
tc qdisc add dev eth0 cake bandwidth
At lower bandwidths, the transmission time of a single GSO segment can add
an unacceptable amount of latency due to HOL blocking. Furthermore, with a
software shaper, any tuning mechanism employed by the kernel to control the
maximum size of GSO segments is thrown off by the artificial limit on
The ingress mode is meant to be enabled when CAKE runs downlink of the
actual bottleneck (such as on an IFB device). The mode changes the shaper
to also account dropped packets to the shaped rate, as these have already
traversed the bottleneck.
Enabling ingress mode will also tune the AQM to
...since no one complained. If no one continues to complain, I'll
resubmit to net-next with that version later today :)
-Toke
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