Re: [PATCH v6 0/4] Add Airtime Queue Limits (AQL) to mac80211

[Kan Yan <kyan@google.com>]

Patchset v6 works for me with ath10k driver.  AQL does its job as
expected and tests show very significant reduction in latency in
congested environment. The txq stuck issue in patchset v4 got fixed.

However, the device's total pending airtime count still underflows
sometimes. Even though it doesn't cause apparent side effect, there is
some issue with the pending airtime update and needs further
debugging.

Regards,
Kan


On Wed, Oct 23, 2019 at 2:59 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> This series is a first attempt at porting the Airtime Queue Limits concept from
> the out-of-tree ath10k implementation[0] to mac80211. This version takes Kan's
> patch to do the throttling in mac80211, and replaces the driver API with the
> mechanism from the previous version of my series, which instead calculated the
> expected airtime at dequeue time inside mac80211, storing it in the SKB cb
> field.
>
> This series also imports Felix' airtime calculation code from mt76 into
> mac80211, adjusting the API so it can be used from TX dequeue, by extracting the
> latest TX rate from the tx_stats structure kept for each station.
>
> As before, I've only compile tested this (lacking the proper hardware to do more
> testing). So I'm hoping someone with a proper testing setup can take the whole
> thing for a spin... :)
>
> The series is also available in my git repo here:
> https://git.kernel.org/pub/scm/linux/kernel/git/toke/linux.git/log/?h=mac80211-aql-06
>
> Changelog:
>
> v6:
>   - Fix sta lookup in ieee80211_report_used_skb().
>   - Move call to ieee80211_sta_update_pending_airtime() to a bit later in
>     __ieee80211_tx_status()
> v5:
>   - Add missing export of ieee80211_calc_rx_airtime() and make
>     ieee80211_calc_tx_airtime_rate() static (kbuildbot).
>   - Use skb_get_queue_mapping() to get the AC from the skb.
>   - Take basic rate configuration for the BSS into account when calculating
>     multicast rate.
> v4:
>   - Fix calculation that clamps the maximum airtime to fit into 10 bits
>   - Incorporate Rich Brown's nits for the commit message in Kan's patch
>   - Add fewer local variables to ieee80211_tx_dequeue()
> v3:
>   - Move the tx_time_est field so it's shared with ack_frame_id, and use units
>     of 4us for the value stored in it.
>   - Move the addition of the Ethernet header size into ieee80211_calc_expected_tx_airtime()
> v2:
>   - Integrate Kan's approach to airtime throttling.
>   - Hopefully fix the cb struct alignment on big-endian architectures.
>
> ---
>
> Kan Yan (1):
>       mac80211: Implement Airtime-based Queue Limit (AQL)
>
> Toke Høiland-Jørgensen (3):
>       mac80211: Shrink the size of ack_frame_id to make room for tx_time_est
>       mac80211: Import airtime calculation code from mt76
>       mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue
>
>
>  include/net/cfg80211.h     |    7 +
>  include/net/mac80211.h     |   45 +++++
>  net/mac80211/Makefile      |    3
>  net/mac80211/airtime.c     |  390 ++++++++++++++++++++++++++++++++++++++++++++
>  net/mac80211/cfg.c         |    2
>  net/mac80211/debugfs.c     |   78 +++++++++
>  net/mac80211/debugfs_sta.c |   43 ++++-
>  net/mac80211/ieee80211_i.h |    8 +
>  net/mac80211/main.c        |    9 +
>  net/mac80211/sta_info.c    |   32 ++++
>  net/mac80211/sta_info.h    |    8 +
>  net/mac80211/status.c      |   33 ++++
>  net/mac80211/tx.c          |   69 +++++++-
>  13 files changed, 709 insertions(+), 18 deletions(-)
>  create mode 100644 net/mac80211/airtime.c
>