On 11/25/14 11:33, John Fastabend wrote:

On 11/25/2014 08:19 AM, Roopa Prabhu wrote:

I agree its needed but your already out of sync for some period of time
why the software/hardware tables are being programmed. There is no global
sw/hw commit operation.

I'm not sure it matters if the time being out of sync is a touch longer
because we go to user space to fix it. But agreed it can be supported.

Recent netfilter has 2 phase commit built in. Maybe we can generalize
that?
Note, there are use cases where it is important to do rollbacks.
If i am doing a distributed router, then to make sure a FIB/NH entries
are properly synced in across the cluster is extremely important. You
cant justify letting a few packets sneak in the wrong path.
in other words, strong consistency is important.
Having said that things can be worked around (and i would not use
2pc for the example use case i gave); however, that doesnt negate
the fact we need it.

cheers,
jamal