From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Johannes Berg <johannes@sipsolutions.net>,
Herbert Xu <herbert@gondor.apana.org.au>,
Arend Van Spriel <arend.vanspriel@broadcom.com>
Cc: Felix Fietkau <nbd@nbd.name>,
linux-wireless@vger.kernel.org,
Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH 5/5] mac80211: set NETIF_F_LLTX when using intermediate tx queues
Date: Tue, 16 Apr 2019 10:33:01 +0100 [thread overview]
Message-ID: <87ef62uwfm.fsf@toke.dk> (raw)
In-Reply-To: <eab39dd804405854997e50102f3d0ff925feb8d2.camel@sipsolutions.net>
Johannes Berg <johannes@sipsolutions.net> writes:
> On Tue, 2019-04-16 at 16:36 +0800, Herbert Xu wrote:
>> On Tue, Apr 16, 2019 at 10:04:24AM +0200, Arend Van Spriel wrote:
>> >
>> > I was just writing up an email clarifying my question. But let me summarize
>> > this email thread. The patch from Felix adds this flag in mac80211 for
>> > drivers that indicate to support pulling packets from the internal TXQ in
>> > mac80211. I found it is deprecated, but as Felix mentioned it is used in
>> > various parts of the network subsystem, ie. batman-adv, bridge, vlan, tunnel
>> > implementations. So its use seems to be restricted rather than deprecated.
>> > Given your response above I guess my question would be to get details about
>> > what you call "proper design" as I think you are saying with that it is not
>> > needed, right?
>>
>> Essentially the only time it would be OK to use LLTX in its current
>> form is if you have no TX queue/congestion feedback which is clearly
>> not the case with wireless drivers.
>
> It is true because we have an entire buffering layer in mac80211 (in
> this case at least) and never push back to the stack.
I'm wondering if we should be? For instance, fq_codel returns
NET_XMIT_CN if it drops a packet from the same flow that it enqueued to.
We could conceivably do the same in mac80211, although we'd have to
carry the return value out through quite a few layers. Not sure if this
is worth it?
Eric, do you have any insight into what impact the _CN return has from
fq_codel?
-Toke
next prev parent reply other threads:[~2019-04-16 9:33 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-16 17:06 [PATCH 1/5] mac80211: mesh: drop redundant rcu_read_lock/unlock calls Felix Fietkau
2019-03-16 17:06 ` [PATCH 2/5] mac80211: fix memory accounting with A-MSDU aggregation Felix Fietkau
2019-03-16 18:12 ` Toke Høiland-Jørgensen
2019-03-16 17:06 ` [PATCH 3/5] mac80211: calculate hash for fq without holding fq->lock in itxq enqueue Felix Fietkau
2019-03-16 18:13 ` Toke Høiland-Jørgensen
2019-03-16 17:06 ` [PATCH 4/5] mac80211: run late dequeue late tx handlers without holding fq->lock Felix Fietkau
2019-03-16 18:13 ` Toke Høiland-Jørgensen
2022-12-05 9:46 ` Wen Gong
2022-12-05 9:46 ` Wen Gong
2022-12-07 6:30 ` Wen Gong
2022-12-07 6:30 ` Wen Gong
2022-12-12 8:31 ` Wen Gong
2022-12-12 8:31 ` Wen Gong
2019-03-16 17:06 ` [PATCH 5/5] mac80211: set NETIF_F_LLTX when using intermediate tx queues Felix Fietkau
2019-03-16 18:14 ` Toke Høiland-Jørgensen
2019-04-14 9:44 ` Arend Van Spriel
2019-04-14 11:19 ` Felix Fietkau
2019-04-14 12:34 ` Arend Van Spriel
2019-04-16 7:34 ` Arend Van Spriel
2019-04-16 7:44 ` Herbert Xu
2019-04-16 8:04 ` Arend Van Spriel
2019-04-16 8:36 ` Herbert Xu
2019-04-16 8:37 ` Johannes Berg
2019-04-16 9:17 ` Arend Van Spriel
2019-04-16 9:29 ` Herbert Xu
2019-04-16 9:33 ` Toke Høiland-Jørgensen [this message]
2019-04-16 9:33 ` Johannes Berg
2019-04-16 9:37 ` Herbert Xu
2019-04-16 9:39 ` Johannes Berg
2019-04-16 10:02 ` Toke Høiland-Jørgensen
2019-04-17 2:11 ` Herbert Xu
2019-04-17 8:28 ` Toke Høiland-Jørgensen
2019-04-16 13:13 ` Herbert Xu
2019-04-16 13:18 ` Toke Høiland-Jørgensen
2019-04-17 3:38 ` Herbert Xu
2019-04-17 9:09 ` Toke Høiland-Jørgensen
2019-04-17 9:16 ` Arend Van Spriel
2019-04-17 9:17 ` Toke Høiland-Jørgensen
2019-04-23 12:41 ` Johannes Berg
2019-04-25 8:35 ` Herbert Xu
2019-04-25 8:39 ` Johannes Berg
2019-04-25 8:44 ` Herbert Xu
2019-04-25 8:49 ` Johannes Berg
2019-04-16 19:13 ` Johannes Berg
2019-04-17 2:13 ` Herbert Xu
2019-04-16 9:38 ` Toke Høiland-Jørgensen
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