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Message-ID: <e40e97d46c0f602677e654bd15c5e14f05274852.camel@sipsolutions.net>
Subject: Re: [PATCH v6 1/4] mac80211: Shrink the size of ack_frame_id to
 make room for tx_time_est
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= <toke@redhat.com>
Cc:     linux-wireless@vger.kernel.org,
        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>, Kan Yan <kyan@google.com>,
        Rajkumar Manoharan <rmanohar@codeaurora.org>,
        Kevin Hayes <kevinhayes@google.com>
Date:   Fri, 08 Nov 2019 11:03:15 +0100
In-Reply-To: <157182474063.150713.16132669599100802716.stgit@toke.dk>
References: <157182473951.150713.7978051149956899705.stgit@toke.dk>
         <157182474063.150713.16132669599100802716.stgit@toke.dk>
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On Wed, 2019-10-23 at 11:59 +0200, Toke Høiland-Jørgensen wrote:
> From: Toke Høiland-Jørgensen <toke@redhat.com>
> 
> To implement airtime queue limiting, we need to keep a running account of
> the estimated airtime of all skbs queued into the device. Do to this
> correctly, we need to store the airtime estimate into the skb so we can
> decrease the outstanding balance when the skb is freed. This means that the
> time estimate must be stored somewhere that will survive for the lifetime
> of the skb.
> 
> To get this, decrease the size of the ack_frame_id field to 6 bits, and
> lower the size of the ID space accordingly. This leaves 10 bits for use for
> tx_time_est, which is enough to store a maximum of 4096 us, if we shift the
> values so they become units of 4us.
> 

I've applied this as preparation.

johannes