[Make-wifi-fast] [Cake] Cake in mac80211
toke at redhat.com
Wed Feb 5 11:16:44 EST 2020
Dave Taht <dave at taht.net> writes:
> Bjørn Ivar Teigen <bjorn at domos.no> writes:
>> Thanks for the feedback!
>> Some comments and questions added inline.
>> On Tue, 4 Feb 2020 at 18:07, Dave Taht <dave.taht at gmail.com> wrote:
>> On Tue, Feb 4, 2020 at 7:25 AM Jonathan Morton
>> <chromatix99 at gmail.com> wrote:
>> > > On 4 Feb, 2020, at 5:20 pm, Bjørn Ivar Teigen <bjorn at domos.no>
>> > >
>> > > Are there any plans, work or just comments on the idea of
>> implementing cake in mac80211 as was done with fq_codel?
>> > To consider doing that, there'd have to be a concrete benefit to
>> doing so.
>> Research is research! :) Everything is worth trying! There's got
>> to be
>> some better ideas out there, and we have a long list of things we
>> could have done to keep improving wifi had funding not run out.
>> We barely scratched the surface of this list.
>> > Most of Cake's most useful features, beyond what fq_codel
>> already supports, are actually implied or even done better by the
>> WiFi environment and the mac80211 layer adaptation (particularly
>> airtime fairness).
>> In my opinion(s)
>> A) I think ack-filtering will help somewhat on 802.11n, but it's
>> worth the added cpu cost on an AP and I'd prefer hosts reduce
>> ack load in the tcp stack (IMHO, others may differ, it's worth
>> B) The underlying wifi scheduler essentially does per host fq
>> than cake can (because it's layer 2 vs layer 3), as per jonathan's
>> comment above
>> C) Instead of using a 8 way set associative hash and 1024 queues,
>> fq_codel for wifi uses 4096 with a disambiguation pointer for
>> collisions. Seems good enough.
>> Didn't catch that before. Are the extra queues there because of the
>> different access categories on Wi-Fi? Seems like that would mean most
>> of them are not in use considering how little traffic is marked with
> I wasn't counting those. There's one set of 4k queues per access
Nit: not per access class; they're shared across the whole phy.
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