[Make-wifi-fast] a cheer up tweet for y'all

Dave Taht dave.taht at gmail.com
Thu Jan 11 04:31:07 EST 2024

i so wish more of what I discussed 8 years ago, had made it to the
chipmakers. Minstrel-blues, in the end, didn't work out, but seemed so
promising (coupled rate and power control).

On Wed, Jan 10, 2024 at 1:23 PM Bob McMahon <bob.mcmahon at broadcom.com> wrote:
> > Well, the original context of the question was "Linux WiFi drivers are
> > terrible, what can we do about that", and, well, providing proper
> > upstream drivers at HW launch is the way to solve that.
> This is out of the scope of chip makers for modern chips. The os drivers are written by system integrators - specialization has divided these tasks. Chip makers don't affect open vs closed source drivers of systems.  Think of a WiFi chip now as transistors with a small microcontroller and not a linux NIC.

Mediatek has had an "Upstream first" wifi chipset development policy
for many years now, the mt76 got competetive and the mt79 is looking
really good. It has a very minimal blob attached to it, and a decent
API (with a couple exceptions).

The offloaded cpu in the ath10k was actually quite powerful, and had
that code been more commonly available, it would not have taken so
many years and a mere *one* guy licensed to work on it, to get the
ath10k firmware up to snuff.


The R/T OS on that "microcontroller" was a nightmare of spaghetti
written by EEs on crack.

I quiver in fear about even less open firmware blobs than that.
> One can argue that chip makers don't provide documents to open-source developers, which is mostly accurate. But documents aren't the blocker.

Oh, they are key to understanding what the chip can be made to do
outside of the scope of the original designers.

> I think an open source community would have to innovate to a level to drive the use of chips coming off a foundry line for a chip maker to consider assigning resources to support open-source teams. Old chips with 10+ year old NRE doesn't justify any investment by anyone.

I would merely like a competent OS developer to be present from day
one of a new or being revised design to provide useful feedback from
the field about what ideas are BS and which are not. For example,
recently I turned down a gig that was trying to use offloads to speed
up crypto processing of DNS packets, which historically, has never
been worthwhile, as the overhead of handing off the co-processor was
far far greater for small packets than doing it on the cpu was. The
real innovation for crypto processing was in adding better cpu

I also thought mu-mimo (one way broadcast to multiple stations) was a
total waste of time. I do have some hope for the more bi-directional
stuff in ofdma, but given the backoff structure of the wifi mac, and
the nature of tcp, mu-mimo introduced complexity for sub-zero benefit.
Merely firing all the people that marketed that and hiring on a few
more clued network developers instead, would have helped.

OS developers also have needs and desires for useful stuff in hardware
that are sometimes bogus, and sometimes genuinely useful. In wifi, I
have longed for a tx or rx is almost done interrupt, being able to
directly dma from/to the kernel layout of a skb, a completion
interrupt and a dozen other things that i outlined in the presentation
above. As for bogus, someone added NAPI support to the ath10k when it
is totally unneeded at even the maximum interrrupt rate. No idea why
that happened.

Lastly, hw or firmware that presents sane APIs to the overlying os
frequently does not happen due to lack of communication about what can
and should be done in software,
> I think the server market & structure & level of cloud innovation make things different for ethernet NICs.
> Bob
> On Wed, Jan 10, 2024 at 3:23 AM Toke Høiland-Jørgensen <toke at toke.dk> wrote:
>> Bob McMahon <bob.mcmahon at broadcom.com> writes:
>> > This approach is not going to work. Sun workstations as the forwarding
>> > planes for WiFi doesn't work nor scale and is cost & power inefficient. The
>> > WiFi forwarding plane needs to be all hardware and not based off of BSD. It
>> > has to be like a port asic in an ethernet switch. No SoC.
>> >
>> > Ethernet NICs are targeting servers where the workstation/NIC model does
>> > work. WiFi is never going to be the basis for cloud servers.
>> Well, the original context of the question was "Linux WiFi drivers are
>> terrible, what can we do about that", and, well, providing proper
>> upstream drivers at HW launch is the way to solve that.
>> And even so, every Linux-based CPE in existence is a contradiction of
>> you assertion that software-based WiFi forwarding is "not going to
>> work". On the contrary, the SOCs with proper open source drivers and
>> support are the ones that work the best, because that means we can run
>> OpenWrt on them instead of the vendor crapware that they ship with.
>> -Toke
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40 years of net history, a couple songs:
Dave Täht CSO, LibreQos

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