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Message-ID: <e1798568decc6df9b44ce97f48be523bdc92bdc4.camel@sipsolutions.net>
Subject: Re: [PATCH mac80211-next v8] mac80211: Switch to a virtual
 time-based airtime scheduler
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= <toke@redhat.com>,
        linux-wireless@vger.kernel.org
Cc:     make-wifi-fast@lists.bufferbloat.net, Felix Fietkau <nbd@nbd.name>,
        Rajkumar Manoharan <rmanohar@codeaurora.org>,
        Kan Yan <kyan@google.com>, Yibo Zhao <yiboz@codeaurora.org>
Date:   Wed, 23 Jun 2021 11:14:18 +0200
In-Reply-To: <20210507094851.180838-1-toke@redhat.com> (sfid-20210507_114946_866610_98578A77)
References: <20210507094851.180838-1-toke@redhat.com>
         (sfid-20210507_114946_866610_98578A77)
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On Fri, 2021-05-07 at 11:48 +0200, Toke Høiland-Jørgensen wrote:
> This switches the airtime scheduler in mac80211 to use a virtual time-based

Generally, we prefer <=72 columns in commit messages ... I started
reformatting, but then your code also has a lot of places that go over
80 columns, so I gave up ... Can you please do that?

Some refactoring, e.g. in sta_apply_parameters(), may also be in order.
> +/**
> + * struct airtime_sched_info - state used for airtime scheduling and AQL
> + *
> + * @lock: spinlock that protects all the fields in this struct
> + * @active_txqs: rbtree of currently backlogged queues, sorted by virtual time
> + * @schedule_pos: the current position maintained while a driver walks the tree
> + *                with ieee80211_next_txq()
> + * @active_list: list of struct airtime_info structs that were active within
> + *               the last AIRTIME_ACTIVE_DURATION (100 ms), used to compute weight_sum
> + * @last_weight_update: used for rate limiting walking active_list
> + * @last_schedule_time: tracks the last time a transmission was scheduled; used
> + *                      for catching up v_t if no stations are eligible for transmission.
> + * @v_t: global virtual time; queues with v_t < this are eligible for transmission
> + * @weight_sum: total sum of all active stations used for dividing airtime
> + * @weight_sum_reciprocal: reciprocal of weight_sum (to avoid divisions in fast
> + *                         path - see comment above IEEE80211_RECIPROCAL_DIVISOR_64)
> + * @aql_txq_limit_low: AQL limit when total outstanding airtime is < IEEE80211_AQL_THRESHOLD
> + * @aql_txq_limit_high: AQL limit when total outstanding airtime is > IEEE80211_AQL_THRESHOLD

This is also needlessly way over.

Thanks,
johannes