Re: [POC/GIT] mac80211 multicast rate selection (help wanted!)

[David Lamparter <equinox@diac24.net>]

On Fri, Aug 18, 2017 at 03:49:39PM -0700, Ben Greear wrote:
> On 08/18/2017 03:29 PM, David Lamparter wrote:
> > I've taken up an hacking endeavour in trying to improve multicast on
> > wifi, specifically to get it off the stupid 1 MBit rate.  Before anyone
> > yells "that's not allowed by the spec" - it actually is, please refer to
> > section 9.7.5 of 802.11-2012. ("... using one of the rates included in
> > the BSSBasicRateSet parameter ...")  Also, Cisco and Aruba are doing
> > this in their enterprise APs, and it's rather nice.
> 
> For ath10k, at least, rate-ctrl is controlled in the firmware.
> But, the driver can set the multicast rate to a fixed value.

Yeah, I've hacked this straight in minstrel_ht, so it's only gonna work
on mac80211 drivers.

The information about which STAs are joined to a multicast group is
available to all drivers though, so, if a hardmac driver has sufficient
information on STA rates, it could still dynamically pick a multicast
rate on a per-packet level and tell that to the MAC.

> I am pretty sure this works on stock firmware, maybe with some driver
> tweaks.  It definitely works on my ath10k-ct driver/firmware (tested on
> the wave-1 stuff, not sure anyone has tested on the wave-2 stuff yet).
> 
> My api is through the ath10k debugfs API, so a kludge at best, but it could
> be wired into a better API with some work.

I actually need to try the CT stuff, particularly the TX rate reporting
-- wonder how useful the information is (cf. above).  Unfortunately the
only ath10k I have is in my plastic router...  a bit annoying to hack
around on.

> I'll read through your stuff when I get a chance.

Thanks in advance, all input appreciated!


-David