I have a question on netpoll and I think it is a good opportunity to ask my question in this thread,

I have always wondered what is the use cases of netpoll anyway?

Some months ago, I was designing a caching mechanism within the network stack. I was just polling in NF_IP_PRE_ROUTING and check some keys in my hash map if it is HIT then I will respond to the incoming request from the kernel via NETPOLL without engaging the real key-value store(Memcached) in the userspace! In miss cases I only let the request go through the kernel network stack and the Memcached application will respond to the request individually. I only update my hash my with respect the outgoing message in NF_IP_POST_ROUTING. I intended to reduce the latency of the key-value stores' requests at the data centers since these key-value stores are widely deployed in the data center at Facebook and Google.

In my scenario, I only used netpoll as a hack to make my code working though, however, I never figure out, what problem netpoll intended to solve.

Thank you,

Alireza