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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Kan Yan <kyan@google.com>
Cc:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org,
        Make-Wifi-fast <make-wifi-fast@lists.bufferbloat.net>,
        ath10k@lists.infradead.org, John Crispin <john@phrozen.org>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Felix Fietkau <nbd@nbd.name>,
        Rajkumar Manoharan <rmanohar@codeaurora.org>,
        Kevin Hayes <kevinhayes@google.com>
Subject: Re: [PATCH v6 0/4] Add Airtime Queue Limits (AQL) to mac80211
In-Reply-To: <CA+iem5s6jDNR+yA21UB_zJiZeVxix_QaO6RYw6sN69j2859zFw@mail.gmail.com>
References: <157182473951.150713.7978051149956899705.stgit@toke.dk> <CA+iem5s6jDNR+yA21UB_zJiZeVxix_QaO6RYw6sN69j2859zFw@mail.gmail.com>
Date:   Thu, 07 Nov 2019 11:55:05 +0100
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Kan Yan <kyan@google.com> writes:

> Patchset v6 works for me with ath10k driver.  AQL does its job as
> expected and tests show very significant reduction in latency in
> congested environment. The txq stuck issue in patchset v4 got fixed.

Awesome! Thank you for testing!

> However, the device's total pending airtime count still underflows
> sometimes. Even though it doesn't cause apparent side effect, there is
> some issue with the pending airtime update and needs further
> debugging.

Huh, it *under*flows? That's... interesting. Cloned SKBs? Or maybe the
tx_time_est field is being set in some other place?

Could I get you to add a dump_stack() to the underflow test so we can
get an idea of where that happens?

-Toke