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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Kan Yan <kyan@google.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>
Subject: Re: [PATCH v3 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue
In-Reply-To: <CA+iem5sCTsPe4PW=0j20NoAratvdCvB0ss7zO3wMWLcirXsLgg@mail.gmail.com>
References: <157140962094.2866668.3383184317264069493.stgit@toke.dk> <157140962534.2866668.1182822483250825739.stgit@toke.dk> <CA+iem5sCTsPe4PW=0j20NoAratvdCvB0ss7zO3wMWLcirXsLgg@mail.gmail.com>
Date:   Sat, 19 Oct 2019 13:12:55 +0200
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Kan Yan <kyan@google.com> writes:

>> +       if (local->airtime_flags & AIRTIME_USE_AQL) {
>> +               airtime =3D ieee80211_calc_expected_tx_airtime(hw, vif, =
txq->sta,
>> +                                                            skb->len);
>> +               if (airtime) {
>> +                       /* We only have 10 bits in tx_time_est, so store=
 airtime
>> +                        * in increments of 4 us and clamp that to 2**10=
.
>> +                        */
>> +                       info->tx_time_est =3D min_t(u32, airtime >> 2, 1=
 << 10);
>> +                       ieee80211_sta_update_pending_airtime(local, tx.s=
ta, ac,
>> +                                                            airtime, fa=
lse);
>> +               }
>> +       }
>> +
>
> It should be:
>                          ieee80211_sta_update_pending_airtime(local, tx.s=
ta, ac,
>
> info->tx_time_est << 2, false);
>
> The airtime rounded to 4us (info->tx_time_est << 2), instead of the
> original airtime should be used when registering the pending airtime,
> to keep it consistent with airtime subtracted when the skb is freed.

Yes, I realised that last night as well. The rounding is also off (max
is 2**10-1, not 2**10. Will send a v4 :)

-Toke