On Mon, 8 Jan 2018 22:44:27 +0100
Peter Zijlstra [off-list ref] wrote:

On Mon, Jan 08, 2018 at 10:31:09PM +0100, Jesper Dangaard Brouer wrote:

quoted

I did expected the issue to get worse, when you load the Pi with
network traffic, as now the softirq time-budget have to be shared
between networking and USB/DVB. Thus, I guess you are running TCP and
USB/mpeg2ts on the same CPU (why when you have 4 CPUs?...)  

Isn't networking also over USB on the Pi ?

Darn, that is true. Looking at the dmesg output in http://ix.io/DOg:

[    0.405942] usbcore: registered new interface driver smsc95xx
[    5.821104] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

I don't know enough about USB... is it possible to control which CPU
handles the individual USB ports, or on some other level (than ports)?

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer