[Ns-developers] setting available system memory on a node?

[Florian Westphal]

Mathieu Lacage <mathieu.lacage at sophia.inria.fr> wrote:
> > How would you like to have this exposed on the ns3 side?
> > I am thinking node should have something like
> > 
> > .AddAttribute ("System Memory", "The amount of memory (in Ki Bytes) "
> > 		"available to this stack", ...
> 
> sounds ok for me (although I have no idea what you would use this for :)

Linux runs on pretty much anything from mobile phones to 64k-Processor
clusters, and the stack behaviour is very different depending on the
system memory available. The NSC Linux stacks now available have about
390 MB memory available. I will probably raise this to one GB in the
2.6.29 stack port. One can already change it (sort of, for TCP anyway) via
NSCs buffer_size() method (which tweaks tcp memory sysctls), but I
believe it makes more sense to
1) have an NSC API to change the memory (so all stacks adjust
   automatically at stack init time).
2) have a way (in ns-3) to specify memory settings (e.g., if your
   simulation is about smart phones running linux, you should
   probably lower memory settings accordingly).

> > Maybe it should be put on the back burner until the long-planned (well,
> > long planned by me, anyway) ns-3-nsc rework is completed (my plan
> > was to introduce an "nsc node" object, which could then pass such
> > an attribute on to NSC).
> 
> Why can't you add this attribute to NscTcpL4Protocol ?

I could, but NSC can also run SCTP or DCCP, so i would like to
avoid making it a TCP property.

Thanks, Florian