[Make-wifi-fast] openwifi presentation

[Jon Pike]

Interesting stuff...   One thing that occurred to me,  that they didnt
mention...  doing an intermediate step,  i.e.  make a stripped down FPGA
dev board,  vs the Xylinx or whoever's standard dev board.  Even with a
radio chipset and parts also on it, could be done much cheaper, and still
be a dev platform.

I also understand that if you could raise the $$$$, and push an ASIC out,
theres a much greater chance of large scale acceptance.  But, it is a lot
of $$$$, and for a single version.

Putting out a dedicated FPGA dev board for $100-200 would let a lot of
people play with it,  students and SW developers.

On Tue, Jun 22, 2021, 9:00 AM <make-wifi-fast-request at lists.bufferbloat.net>
wrote:

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> Today's Topics:
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>    1. the myth of spectrum scarcity (Dave Taht)
>    2. openwifi presentation (Dave Taht)
>    3. Re: [PATCH mac80211-next v8] mac80211: Switch to a virtual
>       time-based airtime scheduler (Toke Høiland-Jørgensen)
>
>
>
> ---------- Forwarded message ----------
> From: Dave Taht <dave.taht at gmail.com>
> To: Make-Wifi-fast <make-wifi-fast at lists.bufferbloat.net>
> Cc:
> Bcc:
> Date: Mon, 21 Jun 2021 09:55:24 -0700
> Subject: [Make-wifi-fast] the myth of spectrum scarcity
> this was really good:
>
> https://ecfsapi.fcc.gov/file/7020396128.pdf
>
>
> --
> Latest Podcast:
> https://www.linkedin.com/feed/update/urn:li:activity:6791014284936785920/
>
> Dave Täht CTO, TekLibre, LLC
>
>
>
>
> ---------- Forwarded message ----------
> From: Dave Taht <dave.taht at gmail.com>
> To: Make-Wifi-fast <make-wifi-fast at lists.bufferbloat.net>
> Cc:
> Bcc:
> Date: Mon, 21 Jun 2021 10:07:23 -0700
> Subject: [Make-wifi-fast] openwifi presentation
>
> https://media.libreplanet.org/u/libreplanet/m/openwifi-project-the-dawn-of-the-free-libre-wifi-chip/
>
> --
> Latest Podcast:
> https://www.linkedin.com/feed/update/urn:li:activity:6791014284936785920/
>
> Dave Täht CTO, TekLibre, LLC
>
>
>
>
> ---------- Forwarded message ----------
> From: "Toke Høiland-Jørgensen" <toke at redhat.com>
> To: Felix Fietkau <nbd at nbd.name>
> Cc: make-wifi-fast at lists.bufferbloat.net, Rajkumar Manoharan <
> rmanohar at codeaurora.org>, Kan Yan <kyan at google.com>, Yibo Zhao <
> yiboz at codeaurora.org>, linux-wireless at vger.kernel.org
> Bcc:
> Date: Tue, 22 Jun 2021 16:25:03 +0200
> Subject: Re: [Make-wifi-fast] [PATCH mac80211-next v8] mac80211: Switch to
> a virtual time-based airtime scheduler
> Toke Høiland-Jørgensen <toke at redhat.com> writes:
>
> > This switches the airtime scheduler in mac80211 to use a virtual
> time-based
> > scheduler instead of the round-robin scheduler used before. This has a
> > couple of advantages:
> >
> > - No need to sync up the round-robin scheduler in firmware/hardware with
> >   the round-robin airtime scheduler.
> >
> > - If several stations are eligible for transmission we can schedule both
> of
> >   them; no need to hard-block the scheduling rotation until the head of
> the
> >   queue has used up its quantum.
> >
> > - The check of whether a station is eligible for transmission becomes
> >   simpler (in ieee80211_txq_may_transmit()).
> >
> > The drawback is that scheduling becomes slightly more expensive, as we
> need
> > to maintain an rbtree of TXQs sorted by virtual time. This means that
> > ieee80211_register_airtime() becomes O(logN) in the number of currently
> > scheduled TXQs because it can change the order of the scheduled stations.
> > We mitigate this overhead by only resorting when a station changes
> position
> > in the tree, and hopefully N rarely grows too big (it's only TXQs
> currently
> > backlogged, not all associated stations), so it shouldn't be too big of
> an
> > issue.
> >
> > To prevent divisions in the fast path, we maintain both station sums and
> > pre-computed reciprocals of the sums. This turns the fast-path operation
> > into a multiplication, with divisions only happening as the number of
> > active stations change (to re-compute the current sum of all active
> station
> > weights). To prevent this re-computation of the reciprocal from happening
> > too frequently, we use a time-based notion of station activity, instead
> of
> > updating the weight every time a station gets scheduled or de-scheduled.
> As
> > queues can oscillate between empty and occupied quite frequently, this
> can
> > significantly cut down on the number of re-computations. It also has the
> > added benefit of making the station airtime calculation independent on
> > whether the queue happened to have drained at the time an airtime value
> was
> > accounted.
> >
> > Co-developed-by: Yibo Zhao <yiboz at codeaurora.org>
> > Signed-off-by: Yibo Zhao <yiboz at codeaurora.org>
> > Signed-off-by: Toke Høiland-Jørgensen <toke at redhat.com>
>
> Hey Felix
>
> Had a chance to look at this yet? :)
>
> -Toke
>
>
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