RE: How to rte_epoll_wait for IPC?

[Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>]

> -----Original Message-----
> From: Morten Brørup <mb@smartsharesystems.com>
> Sent: Friday, October 6, 2023 5:04 AM
> To: Harman Kalra <hkalra@marvell.com>; Anatoly Burakov
> <anatoly.burakov@intel.com>; David Hunt <david.hunt@intel.com>
> Cc: dev@dpdk.org
> Subject: How to rte_epoll_wait for IPC?
> 
> Dear Harman, Anatoly and David,
> 
> I have been looking somewhat into power management, and have a question
> about rte_epoll:
> 
> Can I use rte_epoll to wait for an event (or interrupt/signal) in one EAL thread,
> generated by another EAL thread?
> 
> Here's a simple use case with two EAL threads:
> 
> 1. The "ingress" thread receives its packets from the NICs, filters the packets
> and puts them into a an rte_ring for the "processing" thread. The "ingress"
> thread can sleep and use RX interrupts to wake up, as shown in the l3fwd-
> power example. All good.
> 
> 2. The "processing" thread receives its packets from the rte_ring. This thread
> should sleep until packets are ready for it in the rte_ring.
> 
> The "ingress" thread knows when it puts packets into the rte_ring, so it can
> signal that event to the "processing" thread, to wake it up; either as an
> interrupt/signal, or through a file descriptor. Is this supported by rte_epoll (or
> other DPDK APIs), and how?
This feature is supported by using rte_wait_until_equal_xx APIs in rte_ring.

> 
> 
> In a generic scenario, an EAL thread could be rte_epoll_wait'ing for a variety of
> event sources. This may require a different, more advanced, solution.
> 
> A solution to the simple use case suffices.
> 
> 
> PS: I'm using the standard acronym IPC in the subject, although I'm asking
> about Inter Thread Communication, not Inter Process Communication. I'm not
> looking for a multi process solution.
> 
> 
> Med venlig hilsen / Kind regards,
> -Morten Brørup