Re: [RFC][PATCH] iproute: Faster ip link add, set and delete

[Eric Dumazet <eric.dumazet@gmail.com>]

On Thu, 2013-03-28 at 18:29 -0700, Eric W. Biederman wrote:

> An interesting thought.  I had a patch I never got around to pushing a
> while back that would have had an effect.
> 
> It is my observation that the vast majority of packet filters apply not
> to the entire machine but to an individual interface.  In fact you have
> to work pretty hard to get tools like tcpdump to dump all of the
> interfaces at once.
> 
> So to speed things up for machines that have a lot of these things the
> idea was to create per device lists for the filters that only needed to
> be run on a single device.  In this case it looks like we could
> potentially create per device lists for of the listening sockets as well.
> 
> In general these lists should be short so the search can also be short.
> 
> But I am curious do you actually have a tcpdump or something similar
> running on your box that is using AF_PACKET sockets?  Perhaps a dhcp
> client?
> 
> I am a little surprised that your default case has anything on the lists
> to trigger any work in the packet_notifier notifier.

Hmm, it might be a local daemon on my lab machine which does a
PACKET_ADD_MEMBERSHIP for each created interface.

So my machine spend time in packet_dev_mclist(), with a quadratic
behavior at rmmod.