Re: [PATCH] mac80211: Simplify queue selection

["Toke Høiland-Jørgensen" <toke@kernel.org>]

Johannes Berg <johannes@sipsolutions.net> writes:

> On Tue, 2022-05-10 at 18:10 +0200, Felix Fietkau wrote:
>> On 10.05.22 17:58, Alexander Wetzel wrote:
>> > Let iTXQ drivers also register four queues in netdev and move queue
>> > assignment to ndo_select_queue(), like it's done for other drivers.
>> > 
>> > This gets rid of a special case in mac80211 and also increases the
>> > chance that when we call skb_get_hash() the skb is still hot in the CPU
>> > buffers.
>> > 
>> > Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
>> 
>> This has the disadvantage of requiring a redundant sta lookup in the tx 
>> path for iTXQ drivers. I think the CPU cost of that one is probably 
>> higher than any potential gain from calling skb_get_hash a bit earlier.
>> 
>
> However, that's independent - we can still calculate the hash there, and
> then bail out, i.e. put it right before the "if (wake_tx_queue) return"
> part, no?
>
> OTOH we don't even need the hash in the other cases, do we?

Nope, that was my point on the "moving it to shared netdev core"
question :)

-Toke