On Sun, 31 Oct 2021 22:50:40 -0700
Jack Humphries <j...@chillysky.com> wrote:
> Hi folks,
>
> Hope all are well. I’m trying to enable interrupts in DPDK so that my network
> receive thread can sleep on an epoll until packets arrive. I am using the
> ixgbe kernel driver and igb_uio userspace driver with an Intel 82599ES 10Gbps
> NIC.
>
> I'm doing roughly the following to enable the interrupts, but the epoll never
> indicates that packets have arrived. The thread only handles packets when the
> epoll times out. I don't even see interrupts arrive from the device when
> monitoring /proc/interrupts.
>
> port_conf.intr_conf.rxq = 1;
>
> ...
>
> CHECK_EQ(rte_eth_dev_rx_intr_ctl_q(kPort, kQueue, RTE_EPOLL_PER_THREAD,
> RTE_INTR_EVENT_ADD, nullptr),
> 0);
> CHECK_EQ(rte_eth_dev_rx_intr_enable(kPort, kQueue), 0);
>
> ...
>
> rte_epoll_event event;
> while (true) {
> int n = rte_epoll_wait(RTE_EPOLL_PER_THREAD, &event, /*maxevents=*/1,
> /*timeout=*/1000);
> if (n == 0) {
> // Timeout expired.
> } else {
> // Received RX interrupt.
> }
> }
>
> Given that I don't see anything coming through in /proc/interrupts, I am
> going to start digging through the ixgbe driver. However, I wanted to ask
> here first to see if my setup is missing anything obvious. I based it closely
> on the l3fwd-power example, though I haven't been able to get that example up
> and running yet since my NIC only has one port plugged in right now and the
> example requires two (COVID building restrictions).
If you are going to use interrupts you need to have MSI-X to get per-queue
interrupts.
The igb_uio driver doesn't support this; you need to use vfio-pci in kernel to
get queue interrupts.
