[ovs-dev] Support for classless QoS configuration

Ben Pfaff blp at nicira.com
Tue Mar 3 17:42:58 UTC 2015


tc_load is called the first time that a queue-related operation happens
on a netdev.  For example, when a netdev is first added to a bridge, and
high-level code calls netdev_get_qos(), netdev-linux will check the
current qdisc and then, if that one is known, call the tc_load function
to find out the current configuration.

On Tue, Mar 03, 2015 at 05:58:21PM +0100, impClaw wrote:
> Thank you for the information, it makes sense, removing the
> conditional made it work nicely. So, I have another question, exactly
> what is tc_load used for? In what case is it called? I can't seem to
> trigger it for a specific qdisc (say HTB). If I get this working, I
> can hopefully contribute my changes to the Open vSwitch project.
> 
> 2015-03-02 17:28 GMT+01:00 Ben Pfaff <blp at nicira.com>:
> > On Mon, Mar 02, 2015 at 04:04:30PM +0100, impClaw wrote:
> >> I have implemented support for classless qdiscs fq_codel, codel, sfq
> >> and red in open vswitch. However, there is a line of code in
> >> 'vswitchd/bridge.c' that forbids configuring a qos without at least
> >> one queue (qos->n_queues < 1):
> >>
> >> 3671     if (!qos || qos->type[0] == '\0' || qos->n_queues < 1) {
> >>
> >> What is the reason behind this? Will it break anything if I remove it?
> >
> > For the existing qdiscs, it didn't make sense to not have any queues.
> > Since you're adding classless qdiscs, I guess you should remove it.
> 
> 
> 
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