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From:   Kan Yan <kyan@google.com>
Date:   Tue, 22 Oct 2019 23:41:47 -0700
Message-ID: <CA+iem5tZ95Jd9htLEdAJMubuFeWeUibK9MhTnTHLWNucX6_cRg@mail.gmail.com>
Subject: Re: [PATCH v4 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on
 packet dequeue
To:     =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org,
        Make-Wifi-fast <make-wifi-fast@lists.bufferbloat.net>,
        ath10k@lists.infradead.org, John Crispin <john@phrozen.org>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Felix Fietkau <nbd@nbd.name>,
        Rajkumar Manoharan <rmanohar@codeaurora.org>,
        Kevin Hayes <kevinhayes@google.com>
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Sender: linux-wireless-owner@vger.kernel.org
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> >> +               if (ieee80211_is_data_qos(hdr->frame_control)) {
> >> +                       qc =3D ieee80211_get_qos_ctl(hdr);
> >> +                       tid =3D qc[0] & 0xf;
> >> +                       ac =3D ieee80211_ac_from_tid(tid);
> >> +               } else {
> >> +                       ac =3D IEEE80211_AC_BE;
> >> +               }
> >
> > The tid/ac is incorrect either here or in __ieee80211_tx_status() when
> > tested with ath10k. The ac is set to AC_BE with test done using BK
> > class traffic, hence the pending airtime get updated for the wrong
> > txq.
>
> Huh, well that won't do, obviously :)
>
> Any idea why it might be wrong?

somehow  ieee80211_is_data_qos() returns false. Besides,  qos_control
field doesn't seems to be set in ieee80211_build_hdr().

> Hmm, I guess we could just get the ac using skb_get_queue_mapping().
> I'll send an update with this fixed for you to try :)
Thanks for the quick update. It is getting much better, but
unfortunately the pending airtime accounting sometimes is still not
correct and cause txq stuck occasionally.


On Tue, Oct 22, 2019 at 4:35 AM Toke H=C3=B8iland-J=C3=B8rgensen <toke@redh=
at.com> wrote:
>
> Kan Yan <kyan@google.com> writes:
>
> >> +               if (ieee80211_is_data_qos(hdr->frame_control)) {
> >> +                       qc =3D ieee80211_get_qos_ctl(hdr);
> >> +                       tid =3D qc[0] & 0xf;
> >> +                       ac =3D ieee80211_ac_from_tid(tid);
> >> +               } else {
> >> +                       ac =3D IEEE80211_AC_BE;
> >> +               }
> >
> > The tid/ac is incorrect either here or in __ieee80211_tx_status() when
> > tested with ath10k. The ac is set to AC_BE with test done using BK
> > class traffic,  hence the pending airtime get updated for the wrong
> > txq.
>
> Hmm, I guess we could just get the ac using skb_get_queue_mapping().
> I'll send an update with this fixed for you to try :)
>
> -Toke
>