[Cerowrt-devel] SQM in mainline openwrt, fq_codel considered for fedora default

[Tom Gundersen]

On Tue, Oct 21, 2014 at 7:44 PM, Michal Schmidt <mschmidt at redhat.com> wrote:
> On 10/21/2014 07:24 PM, Tom Gundersen wrote:
>> I have now subscribed to cerowrt-devel (long overdue), and I would
>> very much appreciate any comments you guys may have on our networking
>> work in systemd. In particular, if there are any more tweaks like
>> making fq_codel the deafult, which would be the reasonable choice for
>> 95% of users (most of whom don't know about these things and would
>> otherwise never touch them), we are very open to suggestions.
>
> An idea: Can networkd configure interfaces' txqueuelen?
> (Though with BQL and codel maybe it's not that important anymore.)

Hm, the way I read the docs, figuring out the "good" values is not
that straight-forward, and doing this will anyway be obsolete soon, so
not sure we should be setting anything by default. However, we
probably should make it much simpler to configure. We could add
support for both ringbuffer and quelength sizes to our link files [0],
so admins colud implement the bufferbloat recommendations by doing
something like:

----8<------
/etc/systemd/network/00-wlan.link
[Match]
Type=wlan

[Link]
TransmitRingBuffer=4
TransmitQueueLength=16
----8<------

(suggestions welcome for the naming of the variables and also for man
page sections).

These settings would then be applied by udev to any udev interface as
it appears (and before libudev notifies applications about its
existence).

Does something like this make sense?

Cheers,

Tom

[0]: <http://www.freedesktop.org/software/systemd/man/systemd.link.html>
[1]: <http://www.bufferbloat.net/projects/bloat/wiki/Linux_Tips>