Questions about interrupts

[Alan Beadle <ab.beadle@gmail.com>]

Hello,

I am trying to use rte_epoll_wait() to avoid rx polling and reduce CPU
utilization while preserving low latency. I am using the Intel X550-T2
NIC with DPDK 23.11 and the ixgbe driver.

I was able to make interrupts work and my process is getting
interrupts when a packet arrives. I followed the example here:
https://stackoverflow.com/questions/69792978/using-interrupts-with-dpdk

Before calling rte_epoll_wait(), I must first arm the interrupt by
calling rte_eth_dev_rx_intr_enable() every time my thread is about to
wait. However, if a packet arrives between these calls, the interrupt
will not work and my process will only resume once the timeout is
reached. This causes huge latency spikes unless my timeout is very
short, and the minimum time of 1ms is still too long to tolerate this
problem, since my goal is to keep latency low.

Here are my questions:
1) Is there a way to prevent the thread from suspending at all if the
interrupt is not "armed" anymore?
2) Is it possible to set a timeout shorter than 1 ms? It looks like
this is not supported by rte_epoll_wait().

Thank you,
-Alan Beadle