Re: [PATCH 0/10] updates for ctnetlink and conntrack core

[Patrick McHardy <kaber@trash.net>]

Patrick McHardy wrote:
> Pablo Neira Ayuso wrote:
> 
>>Basically, at the time that I was working on the ctnetlink patches, I
>>tried to keep in mind the idea of reducing the netlink bandwidth
>>consumption following the principle of just dumping meaningful fields
>>depending on the type of event.
>>
> I think this is something we need to agree on in principle. I'm
> not convinced that we really do save much bandwidth in the
> common case, and that its worth diverging from the usual update
> notifications containing full updates sent by the remaining
> network stack (besides unset fields or fields containing 0).
> 
> I'll see if I can get some numbers of the actual differences
> without too much effort.

In some very unscientific tests it showed a difference of about
4% when dumping everything compared to only diffs (measured
with conntrack accounting enabled). Not something to easily
throw away, but I bet we can easily increase the netlink bandwidth
for ctnetlink by using more reasonable allocation size and
avoiding the netlink_trim call for every single packet.