tap device speed

[Antonio Di Bacco]

I understand, could we use another solution ? Like a memif  interface
in DPDK and libmemif in Linux?

On Mon, Oct 2, 2023 at 11:21 PM Stephen Hemminger
<stephen at networkplumber.org> wrote:
>
> On Mon, 2 Oct 2023 21:13:03 +0200
> Antonio Di Bacco <a.dibacco.ks at gmail.com> wrote:
>
> > I'm doing a test where we have a couple of tap devices, the two
> > devices are seen by testpmd that is setup in forward mode.
> >
> > On the linux side, the two tap devices are confined in different
> > network namespaces and in one namespace we have an iperf server while
> > on the other namespace the iperf client sending either UDP or TCP.
> >
> > I expected a bandwidth in the range of few gpbs while the actual
> > measured bandwidth is a few gigabits.
> >
> > I suppose I need to configure the tap devices with optimized
> > parameters but I don't know where to look for advice.
> >
> > If I try to use the loopback interface I can get something 40 gbps
> > with a command like this:
> >
> > iperf -c 127.0.0.1 -u -i 1 -b 40g -t 10 -l 40000
> >
> > .
>
> Sorry TAP device is inherently slow. It requires copies to/from Linux
> kernel. You are doing well if you get 1 million packets per second.
>
> One thing to check is that checksum is not being done twice.