Re: Network QoS support in applications

Kalle Valo wrote:

Patrick McHardy [off-list ref] writes:

quoted

quoted

Solution 2: SO_PRIORITY with values 256-263

You can actually encode any class handle in SO_PRIORITY, all classful
qdiscs support classification based on this.

But what values should I use in an application? There seems to n+1
different ways to do it, but they all would be specific to my own
setup.

In case of classful qdisc classification, the values need to
match the class handles.

I'm after a universal solution, so that there is no need to modify
applications every time. I would assume that we have a set of rules
for this. If not, we definitely need one.

Classful qdisc configuration is done by the administrator, so
there is no universal solution.

Let's take a bittorrent client as an example. The traffic it generates
is not important and it doesn't matter if bittorrent packets have
lower priority compared to other streams. What SO_PRIORITY value
should all bittorrent clients to use to mark their packets as low
priority (for example background class from IEEE 802.1d Annex G).

Another example is a VoIP application. The packets need to have as low
delay as possible, so they need to be prioritised very high (for
example voice class from 802.1d). What value should such application
use?

If the device is using the default pfifo_fast qdisc, you
can use values 6 and 7 to map to band 0 (highest priority),
0 and 8-15 to map to band 1 and 1-3 and 5 to map to band 2.

For manually set up qdisc hierarchies you need to ask the
user to specify a priority (or class handle) value.

Or should applications use something else than SO_PRIORITY?

Any help is greatly welcomed here :)

--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html