From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: 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>
Subject: Re: [PATCH RFC/RFT 1/4] mac80211: Rearrange ieee80211_tx_info to make room for tx_time_est
Date: Tue, 01 Oct 2019 11:08:30 +0200 [thread overview]
Message-ID: <87v9t8vnn5.fsf@toke.dk> (raw)
In-Reply-To: <fd0d467d352177ac20100239cb18f80310b43fa9.camel@sipsolutions.net>
Johannes Berg <johannes@sipsolutions.net> writes:
> Hi,
>
> Sorry for the long time to review here ...
>
> On Thu, 2019-09-19 at 14:22 +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.
>>
>> Fortunately, we had a couple of bytes left in the 'status' field in the
>> ieee80211_tx_info; and since we only plan to calculate the airtime estimate
>> after the skb is dequeued from the FQ structure, on the control side we can
>> share the space with the codel enqueue time. And by rearranging the order
>> of elements it is possible to have the position of the new tx_time_est line
>> up between the control and status structs, so the value will survive from
>> when mac80211 hands the packet to the driver, and until the driver either
>> frees it, or hands it back through TX status.
>
> Seems reasonable to me, if we end up needing it and don't have an out-
> of-band path (that you seem to have been discussing in this long
> thread too)
Awesome! Any idea for how to make it work on big-endian systems? I got a
splat from the kbuild robot that triggered the BUILD_BUG_ON when
building for m68k. I assume it's the union with codel_time_t that ends
up being aligned wrong...
-Toke
next prev parent reply other threads:[~2019-10-01 9:08 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 12:22 [PATCH RFC/RFT 0/4] Add Airtime Queue Limits (AQL) to mac80211 Toke Høiland-Jørgensen
2019-09-19 12:22 ` [PATCH RFC/RFT 1/4] mac80211: Rearrange ieee80211_tx_info to make room for tx_time_est Toke Høiland-Jørgensen
2019-10-01 8:44 ` Johannes Berg
2019-10-01 9:08 ` Toke Høiland-Jørgensen [this message]
2019-10-01 9:12 ` Johannes Berg
2019-10-01 9:39 ` Toke Høiland-Jørgensen
2019-09-19 12:22 ` [PATCH RFC/RFT 2/4] mac80211: Add API function to set the last TX bitrate for a station Toke Høiland-Jørgensen
2019-10-01 8:46 ` Johannes Berg
2019-10-01 9:09 ` Toke Høiland-Jørgensen
2019-09-19 12:22 ` [PATCH RFC/RFT 3/4] ath10k: Pass last TX bitrate up to mac80211 Toke Høiland-Jørgensen
2019-09-19 12:22 ` [PATCH RFC/RFT 4/4] mac80211: Apply Airtime-based Queue Limit (AQL) on packet dequeue Toke Høiland-Jørgensen
2019-09-19 17:44 ` Peter Oh
2019-09-19 17:46 ` Ben Greear
2019-09-19 17:54 ` Peter Oh
2019-09-19 18:03 ` Peter Oh
2019-09-19 18:18 ` [Make-wifi-fast] " Dave Taht
2019-09-19 20:09 ` John Yates
2019-09-19 20:15 ` Toke Høiland-Jørgensen
2019-09-19 18:03 ` Toke Høiland-Jørgensen
2019-09-20 12:06 ` Lorenzo Bianconi
2019-09-20 12:54 ` Toke Høiland-Jørgensen
2019-09-20 13:06 ` Lorenzo Bianconi
2019-09-20 13:32 ` Toke Høiland-Jørgensen
2019-09-20 22:55 ` Kan Yan
2019-09-21 12:11 ` Toke Høiland-Jørgensen
2019-09-25 7:37 ` Yibo Zhao
2019-09-25 8:11 ` Toke Høiland-Jørgensen
2019-09-25 11:54 ` Yibo Zhao
2019-09-25 12:52 ` Toke Høiland-Jørgensen
2019-09-26 0:27 ` Kan Yan
2019-09-26 0:34 ` Kan Yan
2019-09-26 5:57 ` Toke Høiland-Jørgensen
2019-09-26 6:04 ` Toke Høiland-Jørgensen
2019-09-26 12:53 ` Felix Fietkau
2019-09-26 13:17 ` Toke Høiland-Jørgensen
2019-09-26 13:47 ` Felix Fietkau
2019-09-26 15:19 ` Toke Høiland-Jørgensen
2019-09-27 2:42 ` Kan Yan
2019-09-27 6:12 ` Toke Høiland-Jørgensen
2019-09-27 9:20 ` Yibo Zhao
2019-09-28 20:24 ` Kan Yan
2019-09-29 19:18 ` Toke Høiland-Jørgensen
2019-10-01 4:47 ` Kan Yan
2019-10-01 6:57 ` Toke Høiland-Jørgensen
2019-09-19 14:12 ` [PATCH RFC/RFT 0/4] Add Airtime Queue Limits (AQL) to mac80211 Toke Høiland-Jørgensen
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