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From:   Kan Yan <kyan@google.com>
Date:   Wed, 20 Nov 2019 18:05:13 -0800
Message-ID: <CA+iem5tpfEmaWJ5Mw7xF9fb=XLceZpC1LM4Avo89Mn1fL7YZVw@mail.gmail.com>
Subject: Re: [Make-wifi-fast] [PATCH v8 0/2] Implement Airtime-based Queue
 Limit (AQL)
To:     =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>
Cc:     Dave Taht <dave.taht@gmail.com>,
        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>
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> It would be interesting to get some samples of the actual sojourn time
> as seen by CoDel in mac80211. Might be doable with bpftrace...

I will try to add some trace event to get the sojourn time for the
next round of tests.


On Wed, Nov 20, 2019 at 2:14 AM Toke H=C3=B8iland-J=C3=B8rgensen <toke@redh=
at.com> wrote:
>
> 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
>