Re: [dpdk-dev] [PATCH] examples/l3fwd: support separate buffer pool per port

[Shreyansh Jain <shreyansh.jain@nxp.com>]

Hello Ananyev,

> Hi Shreyansh,
> 
> > > > I tried this patch on MacchiatoBin + 82599 NIC.
> > > > Compared with global-pool mode, per-port-pool mode showed slightly
> > > lower performance in single core test.
> > >
> > > That was my thought too - for the case when queues from multiple
> ports
> > > are handled by the same core
> > > it probably would only slowdown things.
> >
> > Thanks for your comments.
> >
> > This is applicable for cases where separate cores can handle separate
> ports - each with their pools. (somehow I felt that message in commit
> > was adequate - I can rephrase if that is misleading)
> >
> > In case there is enough number of cores available for datapath, such
> segregation can result in better performance - possibly because of
> > drop in pool and cache conflicts.
> > At least on some of NXP SoC, this resulted in over 15% improvement.
> > And, in other cases it didn't lead to any drop/negative-impact.
> 
> If each core manages just one port, then yes definitely performance
> increase is expected.
> If that's the case you'd like enable, then can I suggest to have mempool
> per lcore not per port?

As you have stated below, it's just the same thing with two different views.

> I think it would be plausible for both cases:
> - one port per core (your case).
> - multiple ports per core.

Indeed. For this particular patch, I just chose the first one. Probably because that is the most general use-case I come across.
I am sure the second too has equal number of possible use-cases - but probably someone with access to that kind of scenario would be better suited for validating what is the performance increase.
Do you think it would be OK to have that in and then sometime in future enable the second option?

[...]

-
Shreyansh