[c-nsp] NPE-G2: mixed interrupt/polling packet processing on POS interface

[Philippe Strauss]

Hello c-nsp,

We are running c7200 vxr with NPE-G2, but are seeing way to high CPU
usage (85%) at only 225kPPS in+out.

It _seems_ it's due to the fact we're using a POS interface.
I _guess_, the G2, when using GigE interface, is doing a mixed
interrupt/polling mode for processing each packets.
(like linux NAPI: above a certain PPS value, the driver switch
from interrupt to polling mode). It's a guess.

But the CPU usage is for sure much lower when using only the 3 GigE
embeded on the mainboard.

Keeping interrupt only processing for POS, which may be used
to switch voice traffic, has some rational behind it.

But we're using it only to switch data/ip, and I'm wondering
if there's a way to lower the CPU usage despite using POS?

like a switch to enable mixed interrupt/polling driver on the POS?

would be highly helpfull.

regards.

-- 
Philippe Strauss
av. de Beaulieu 25
1004 Lausanne
http://philou.ch