netdev - Re: Delay sending packets after a wireless roam

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Message-ID: <CACsRnHWzB4LKBTKn80QZPC6Uz3Rs+KXEjjQSTTAHOGXNnGhEUQ@mail.gmail.com>
Date:   Fri, 3 Sep 2021 11:06:42 +0100
From:   Michael Johnson <mjohnson459@...il.com>
To:     netdev@...r.kernel.org
Subject: Re: Delay sending packets after a wireless roam

Hi all,

On Mon, 30 Aug 2021 at 16:37, Michael Johnson <mjohnson459@...il.com> wrote:
> I started seeing this delay after upgrading from Ubuntu 16.04 to 20.04
> but because so much of the wireless stack changed between those
> releases I'm not sure if it's possible to bisect the change?

Since my last email I have managed to test different kernel versions
to narrow it down to something introduced v4.20-rc1. The issue doesn't
exist in v4.19.
I also compiled and tested the mainline and can confirm that the issue
still exists as of 5.14-rc7.

Does anyone have any suspicions about what commits might cause this issue?

I'm currently trying to bisect the remaining commits but my laptop has
a new intel chip that wasn't supported in old kernel versions and I
can't seem to backport the iwlwifi driver with a compiled kernel (I
could use the backport-iwlwifi repo when installing old debian
packages).

Finally, one other thing I've noticed after more testing is the send
gap is almost exactly one second from the last packet sent before a
roam to the first packet received after. This hints to me it might be
scheduling or timeout related?

Kind Regards,
Michael