From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>,
        Johannes Berg <johannes@sipsolutions.net>
Cc:     Arend Van Spriel <arend.vanspriel@broadcom.com>,
        Felix Fietkau <nbd@nbd.name>, linux-wireless@vger.kernel.org,
        Eric Dumazet <eric.dumazet@gmail.com>, netdev@vger.kernel.org
Subject: Re: [PATCH 5/5] mac80211: set NETIF_F_LLTX when using intermediate tx queues
In-Reply-To: <20190416131346.u2uolljlrd5t2jro@gondor.apana.org.au>
References: <87sgvmvg9g.fsf@toke.dk> <773e4dff-29fd-22b4-e4bc-cd5a94c66dc2@broadcom.com> <20190416074444.pdubbh6fbibdnhi7@gondor.apana.org.au> <73b18131-2777-da5c-a6ee-9d9b3e13cd06@broadcom.com> <20190416083636.5ttvezqyhzr2worg@gondor.apana.org.au> <eab39dd804405854997e50102f3d0ff925feb8d2.camel@sipsolutions.net> <87ef62uwfm.fsf@toke.dk> <95f86cf69dee05a176625925657cf0df0e97b5c9.camel@sipsolutions.net> <20190416093707.dtlwcmitzqopaeaw@gondor.apana.org.au> <e4c1a3ca0c0c160b7c271ab83deebcf096f38497.camel@sipsolutions.net> <20190416131346.u2uolljlrd5t2jro@gondor.apana.org.au>
Date:   Tue, 16 Apr 2019 14:18:36 +0100
Message-ID: <87wojut7f7.fsf@toke.dk>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

Herbert Xu <herbert@gondor.apana.org.au> writes:

> On Tue, Apr 16, 2019 at 11:39:56AM +0200, Johannes Berg wrote:
>> 
>> > not to mention
>> > breaking certain applications that rely on congestion feedback?
>> 
>> This I don't understand. The congestion feedback happens through socket
>> buffer space etc. which is still there (as long as nobody sneaks in an
>> skb_orphan() call)
>
> The congestion control happens at two levels. You are right that the
> socket buffer acts as one limit. However, other applications may also
> rely on the TX queue being full as the throttle (by setting a
> sufficiently large socket buffer size).

Do you happen to have an example of an application that does this that
could be used for testing? :)

-Toke