Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Kan Yan <kyan@google.com>
Cc:     Yibo Zhao <yiboz@codeaurora.org>,
        Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org,
        make-wifi-fast@lists.bufferbloat.net,
        John Crispin <john@phrozen.org>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Felix Fietkau <nbd@nbd.name>,
        linux-wireless-owner@vger.kernel.org
Subject: Re: [PATCH RFC/RFT 4/4] mac80211: Apply Airtime-based Queue Limit (AQL) on packet dequeue
In-Reply-To: <CA+iem5uGU0mQ=37dvp-pnvyk_T9o5cp7vOpsi90U9X-rMjtZ5w@mail.gmail.com>
References: <156889576422.191202.5906619710809654631.stgit@alrua-x1> <156889576869.191202.510507546538322707.stgit@alrua-x1> <2f6b649dcb788222e070ebb5593918c7@codeaurora.org> <87y2yc3ieb.fsf@toke.dk> <8c5a3a011f03d4dd4165b838a2b8bc72@codeaurora.org> <87mues35d4.fsf@toke.dk> <CA+iem5sg-YpkBX4VQPzqibN0YApMxtwFsGqjK2cUUrxD_52zPw@mail.gmail.com> <CA+iem5uGU0mQ=37dvp-pnvyk_T9o5cp7vOpsi90U9X-rMjtZ5w@mail.gmail.com>
Date:   Thu, 26 Sep 2019 07:57:31 +0200
Message-ID: <87k19v38hg.fsf@toke.dk>
MIME-Version: 1.0
Content-Type: text/plain; charset=WINDOWS-1252
Content-Transfer-Encoding: quoted-printable
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

Kan Yan <kyan@google.com> writes:

>> > Do you mean we will use airtime reported by FW to calculate
>>
>> > local->airtime_queued in case we have FW reporting airtime?
>> No, the opposite; if the firmware can't report airtime, we can use the
>> estimated values to feed into report_airtime() for the fairness
>> calculation...
> The local->airtime_queued is the 'future' airtime for the packet
> pending the queue. It can't be replaced by the after the fact airtime
> reported from firmware for the frames transmitted.

No, but on tx_completion we could do something like this:

airtime =3D CB(skb)->tx_time ?: CB(skb)->tx_time_est;
ieee80211_report_airtime(sta, airtime);

That way, if the driver sets the tx_time field to something the firmware
reports, we'll use that, and otherwise we'd fall back to the estimate.

Of course, there would need to be a way for the driver to opt out of
this, for drivers that report out of band airtime like ath10k does :)

-Toke