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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Kan Yan <kyan@google.com>, Dave Taht <dave.taht@gmail.com>
Cc:     Rajkumar Manoharan <rmanohar@codeaurora.org>,
        Kevin Hayes <kevinhayes@google.com>,
        Make-Wifi-fast <make-wifi-fast@lists.bufferbloat.net>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        Yibo Zhao <yiboz@codeaurora.org>,
        John Crispin <john@phrozen.org>,
        Johannes Berg <johannes@sipsolutions.net>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Felix Fietkau <nbd@nbd.name>
Subject: Re: [Make-wifi-fast] [PATCH v8 0/2] Implement Airtime-based Queue Limit (AQL)
In-Reply-To: <CA+iem5uVJFcCYpJfhker-48XPrOf3a+NWr-nKnBtGmLX2yB_Lg@mail.gmail.com>
References: <20191115014846.126007-1-kyan@google.com> <CA+iem5vaeLR6v_nZ1YUZhfj32wF0DrvC2nyp8nb8qYAZLQjLdw@mail.gmail.com> <CAA93jw5wTbFV51oFJ6tFHLUMo=bau8fbU65k57bQjOHGJoCkkQ@mail.gmail.com> <CA+iem5s4ZY239Q4=Gwy3WrmVhcdhesirXph6XQoOP5w-nuWcYw@mail.gmail.com> <CAA93jw5t0TwBVv7_DVkJ_-NsVn0ODNHwU0orp2-+LPB45iFVoQ@mail.gmail.com> <CA+iem5uVJFcCYpJfhker-48XPrOf3a+NWr-nKnBtGmLX2yB_Lg@mail.gmail.com>
Date:   Wed, 20 Nov 2019 11:14:08 +0100
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Kan Yan <kyan@google.com> writes:

>> Those were lovely, thanks!!!! Big win. Since you are on patch v10
>> now.... Any chance you could turn ecn on and off and give it a go
>> again in your next test run?
>>
>>
>> Also:
>>
>> --step-size=3D.04 --socket-stats # the first is helpful to gain more
>> detail, the second as to the behavior of the tcp stack.
>
> Thanks for the feedback! I will do more tests in a few days.
>
>
>> Secondly - and AFTER this patchset stablizes, I'd like us to look into
>> returning the codel default to 10ms or less
>> from it's currently 20ms or worse setting. Tis another easy test
>
> Smaller CoDel "target" doesn't work well with wireless because the
> dequeue behavior in wireless driver is very bursty. It is quite often
> dequeues dozens of packets in one burst after one large aggregation is
> completed, so smaller CoDel "target" can cause unnecessary packet
> drop.

It would be interesting to get some samples of the actual sojourn time
as seen by CoDel in mac80211. Might be doable with bpftrace...

-Toke