How to limit testpmd packet generation rate when forward-mode=txonly

How to limit testpmd packet generation rate when forward-mode=txonly

[Francesco]

Hi all,
I'm using testpmd as very simple packet generator to test the
capability of receive packets of my DPDK application. I'm using a
Mellanox CX5 100Gbps card for the test.

I can successfully launch testpmd with options "--forward-mode=txonly
--stats-period=3" to push 10.5MPPS on each of the 2 ports of the NIC
(using just 1 CPU core !!). This is good but I have a couple of
questions which probably are very basic hopefully:

1) can I limit the TX rate to e.g. half the value I'm getting now
(e.g. to 5MPPS) ?

2) if I want to use more than 1 CPU core for testpmd how can I achieve
that? I played with --nb-cores=5 and running testpmd in interactive
mode and then issuing "port config all txq 4" but still no luck...
testpmd will keep using only 1 CPU core

3) when I run testpmd in batch mode I get a nice report about
"throughput (since last show)" every stats period. How can I tell
testpmd to show me PPS/bytes-per-second reporting also when I start
the application with "-i" (interactive mode)?

Thanks a lot for any hint,

Francesco Montorsi

Re: How to limit testpmd packet generation rate when forward-mode=txonly

[Stephen Hemminger]

On Wed, 10 Nov 2021 17:12:12 +0100
Francesco <francesco.montorsi@gmail.com> wrote:

> Hi all,
> I'm using testpmd as very simple packet generator to test the
> capability of receive packets of my DPDK application. I'm using a
> Mellanox CX5 100Gbps card for the test.
> 
> I can successfully launch testpmd with options "--forward-mode=txonly
> --stats-period=3" to push 10.5MPPS on each of the 2 ports of the NIC
> (using just 1 CPU core !!). This is good but I have a couple of
> questions which probably are very basic hopefully:
> 
> 1) can I limit the TX rate to e.g. half the value I'm getting now
> (e.g. to 5MPPS) ?
> 
> 2) if I want to use more than 1 CPU core for testpmd how can I achieve
> that? I played with --nb-cores=5 and running testpmd in interactive
> mode and then issuing "port config all txq 4" but still no luck...
> testpmd will keep using only 1 CPU core
> 
> 3) when I run testpmd in batch mode I get a nice report about
> "throughput (since last show)" every stats period. How can I tell
> testpmd to show me PPS/bytes-per-second reporting also when I start
> the application with "-i" (interactive mode)?
> 
> Thanks a lot for any hint,
> 
> Francesco Montorsi

Use a real packet generator like trex if you need more control.