Re: [v6] ath9k: Switch to using mac80211 intermediate software queues.

[Kalle Valo <kvalo@qca.qualcomm.com>]

Toke Høiland-Jørgensen wrote:
> This switches ath9k over to using the mac80211 intermediate software
> queueing mechanism for data packets. It removes the queueing inside the
> driver, except for the retry queue, and instead pulls from mac80211 when
> a packet is needed. The retry queue is used to store a packet that was
> pulled but can't be sent immediately.
> 
> The old code path in ath_tx_start that would queue packets has been
> removed completely, as has the qlen limit tunables (since there's no
> longer a queue in the driver to limit).
> 
> The mac80211 intermediate software queues offer significant latency
> reductions, and this patch allows ath9k to realise them. The exact gains
> from this varies with the test scenario, but in an access point scenario
> we have seen latency reductions ranging from 1/3 to as much as an order
> of magnitude. We also achieve slightly better aggregation.
> 
> Median latency (ping) figures with this patch applied at the access point,
> with two high-rate stations and one low-rate station (HT20 5Ghz), running
> a Flent rtt_fair_var_up test with one TCP flow and one ping flow going to
> each station:
> 
>                                  Fast station        Slow station
> Default pfifo_fast qdisc:            430.4 ms            638.7 ms
> fq_codel qdisc on iface:              35.5 ms            211.8 ms
> This patch set:                       22.4 ms             38.2 ms
> 
> Median aggregation sizes over the same test:
> 
> Default pfifo_fast qdisc:            9.5 pkts            1.9 pkts
> fq_codel qdisc on iface:            11.2 pkts            1.9 pkts
> This patch set:                     13.9 pkts            1.9 pkts
> 
> This patch is based on Tim's original patch set, but reworked quite
> thoroughly.
> 
> Cc: Tim Shepard <shep@alum.mit.edu>
> Cc: Felix Fietkau <nbd@nbd.name>
> Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>

Perfect, just what I was hoping to see :) Unless something really
surprising comes up I should apply this within the next few days.

-- 
https://patchwork.kernel.org/patch/9419029/

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