Re: [GIT PULL v2] Open vSwitch

On 11/23/2011 5:44 AM, Jamal Hadi Salim wrote:

On Wed, 2011-11-23 at 13:55 +0100, Eric Dumazet wrote:

quoted

Currently thinking about it. I was also waiting Tom Herbert BQL patches.

Excellent. I can test when you have something.

quoted

Several people are interested, and John Fastabend told me he plans to :

 (1) rcu'ify classifiers/actions as needed

Makes sense in most cases. If you have a lot of flow setup/teardown
it may harm.

We could have a CONFIG option to always do locking in some
cases if thats not too ugly.

Another one - but dont see how much you can do about this; useful
when you want to share state (eg multiple flows being policed
by a single rate meter);
An action could be shared across multiple policies i.e you can
have:
match1, action foo instance 1, action bar instance 3
match2, action bar instance3
match3, ....
This could would mean a lock contended across cpus when different
flows hitting match1/2 show up on different cpus.
 

quoted

 (2) add flag to drop qdisc lock on simple or hw qdiscs

Where does config for the hardware happen from?

I assume you mean something like setup_tc() which we have
today to call into into the driver at qdisc create time. This
happens with the RTNL held. I don't see any reason not to also
call into the hardware on qdisc_change() I just haven't done
it yet.

Although I'm pretty sure we don't want to add a new ndo_ops
ever time we have some hardware feature we want to expose.
Assuming there are more than 1 or 2 hw features. So maybe
we could convert to something more generic. A setup_qos()
call that passes an skb with nl attributes.

Is that what you were asking?

quoted

 (3) mq and mqprio call root qdisc and run a pass over classifiers
     actions possibly resetting queue_mapping.

It seems to make sense - but I will wait and see to have better
understanding.

One of the problems this resolves is not being able to
call the classifier-actions until after the queue is
already selected. At this point you can't send it to
a higher/lower priority queue.

I'm traveling for a couple days, but I'll try to get
some actual patches out next week to illustrate this.

Thanks,
John

cheers,
jamal

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