Optimizing kernel compilation / alignments for network performance

[Arnd Bergmann]

On Fri, May 6, 2022 at 10:55 AM Rafał Miłecki <zajec5 at gmail.com> wrote:
> On 6.05.2022 10:45, Arnd Bergmann wrote:
> > On Fri, May 6, 2022 at 9:44 AM Rafał Miłecki <zajec5 at gmail.com> wrote:
> >> With
> >> echo 1 > /sys/class/net/eth0/queues/rx-0/rps_cpus
> >> my NAT speeds were jumping between 2 speeds:
> >> 284 Mbps / 408 Mbps
> >
> > Can you try using 'numactl -C' to pin the iperf processes to
> > a particular CPU core? This may be related to the locality of
> > the user process relative to where the interrupts end up.
>
> I run iperf on x86 machines connected to router's WAN and LAN ports.
> It's meant to emulate end user just downloading from / uploading to
> Internet some data.
>
> Router's only task is doing masquarade NAT here.

Ah, makes sense. Can you observe the CPU usage to be on
a particular core in the slow vs fast case then?

        Arnd