On 29.04.23 09:36, Alexander Wetzel wrote:
...
First I would like to thank you for the cleanups you are doing in
mac80211, as a driver writer [1] I used to scratch my head to
understand the internals.
I work for a french ISP called Free, and actively maintain the
software of all router/gateway devices (couple millions deployed)
We have a very large number of old devices deployed that are >10 years
old but on which we manage to run a mainline kernel. Those are ARM
Kirkwook (armv5 1Ghz) based devices, wifi is Marvell 11n 2.4Ghz (mwl8k
based) + QCA 11ac 5ghz (QCA998X/ath10k).
The CPU was always a bit underpowered for the 11ac card, but I could
reach ~400Mbit/s in a routing test between WAN and Wifi, 100% CPU usage.
Since work started in 2019 on ath10k debloat, I applied that patch [2]
to avoid performance degration.
Since "wifi: mac80211: Drop support for TX push path", it's not
possible to do that anymore, so I did a benchmark to see the impact,
the same routing test caps at 250Mbit/s. I suppose some openwrt users
will be affected also.
Well, I guess calling wake_tx_queue and then transmitting (mostly) one
packet is probably causing that. Now there are some ideas to improve
that by using a kthreads. It's hidden in the discussion here:
https://lore.kernel.org/all/82d5623b-8d21-a8c1-e835-
e446adf96cde@xxxxxxxxxxxxxx/
My problem with doing that *now* is, that I'm working on a invasive
patch set in mac80211. Which will really clean up the old logic and
not just tweak some simple things.
It's mostly sorted out and written, only a few issue left till I can
try it out. But I'm not getting around to wrap that up for work/
private reasons for quite some weeks (really months...) now. Rebasing
and then testing the already working patches for a wake_tx_queue
implementation using kthreads is something I'm hoping to avoid:-)
Now, I've more or less already decided to add the kthread patch to
that series, once I get it stabilized at its current level.
I have some hopes, that I can reuse the reworked PS mechanism to even
simplify such an patch.
I did put the promised patch set aside for quite some time again and
just resumed looking into them a few weeks ago.
They are now good enough that I could share patches moving TX a kthread.
So if you - or anyone else - is interested to check the performance with
kthread TX I would wrap them up and post an RFC for that.
Alexander
