Subject: Re: [PATCH 5/5] mac80211: set NETIF_F_LLTX when using intermediate tx
 queues
To:     =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgensen?= <toke@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        Felix Fietkau <nbd@nbd.name>, linux-wireless@vger.kernel.org,
        Eric Dumazet <eric.dumazet@gmail.com>, netdev@vger.kernel.org,
        Bob McMahon <bob.mcmahon@broadcom.com>
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 <eab39dd804405854997e50102f3d0ff925feb8d2.camel@sipsolutions.net>
 <87ef62uwfm.fsf@toke.dk>
 <95f86cf69dee05a176625925657cf0df0e97b5c9.camel@sipsolutions.net>
 <20190416093707.dtlwcmitzqopaeaw@gondor.apana.org.au>
 <e4c1a3ca0c0c160b7c271ab83deebcf096f38497.camel@sipsolutions.net>
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 <87wojut7f7.fsf@toke.dk>
 <20190417033834.ep6t7r6ttvjek5g7@gondor.apana.org.au>
 <87wojtroar.fsf@toke.dk>
From:   Arend Van Spriel <arend.vanspriel@broadcom.com>
Message-ID: <2662e6d5-25c7-6e40-4381-800f5e289d31@broadcom.com>
Date:   Wed, 17 Apr 2019 11:16:23 +0200
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+ Bob

On 4/17/2019 11:09 AM, Toke Høiland-Jørgensen wrote:
> Herbert Xu <herbert@gondor.apana.org.au> writes:
> 
>> On Tue, Apr 16, 2019 at 02:18:36PM +0100, Toke Høiland-Jørgensen wrote:
>>>
>>>> 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? :)
>>
>> Have a look at
>>
>> commit 6ce9e7b5fe3195d1ae6e3a0753d4ddcac5cd699e
>> Author: Eric Dumazet <eric.dumazet@gmail.com>
>> Date:   Wed Sep 2 18:05:33 2009 -0700
>>
>>      ip: Report qdisc packet drops
>>
>> You should be able to do a UDP flood while setting IP_RECVERR to
>> detect the packet drop due to a full queue which AFAICS will never
>> happen with the current mac80211 setup.
> 
> Yup, got that part. Was just wondering if you know of any applications
> that already do this, that I could test without having to write my
> own... :)

Hi Bob,

Is this something that could be easily implemented in iperf?

Regards,
Arend