Subject: Re: [PATCH openvswitch v3] netlink: Implement & enable memory mapped netlink i/o

From: Thomas Graf <[email-masked]>
Date: Thu, 05 Dec 2013 23:08:31 +0100

On 12/04/2013 11:20 PM, Jesse Gross wrote:
> If enabling rings on demand can be done cleanly that might be best
> solution. To me, it seems difficult to generalize the upcall
> characteristics based on port type.

It would require to reopen sockets but I don't see that as a major
obstacle.

> 16K ports/sockets would seem to be a good upper bound. However, there
> are a couple of factors that might affect that number in the future.
> The first is that port might not be fine-grained enough - for example,
> on an uplink port it would be better to look at MAC or IP address to
> enforce fairness, which would tend to expand the number of sockets
> necessary (although there obviously won't be a 1:1 mapping, which
> means that we might have to come up with a more clever assignment
> algorithm). The second is that Alex has been working on a userspace
> mechanism for enforcing fairness (you probably have seen his recent
> patches on the mailing list), which could reduce the number of unique
> queues from the kernel.

Let's see where we get to with the on demand idea. Defaulting to on
is sitll possible if the number of sockets can be limited again.