On Fri, May 6, 2022 at 10:55 AM Rafał Miłecki [off-list ref] wrote:

On 6.05.2022 10:45, Arnd Bergmann wrote:

quoted

On Fri, May 6, 2022 at 9:44 AM Rafał Miłecki [off-list ref] wrote:

quoted

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