Thanks Stephen. I am just using one RX queue from the NIC. I assume that since 
I don’t need per-queue interrupts here since there is only one queue, I should 
be good using ixgbe+igb_uio?

Thanks,
Jack

> On Nov 1, 2021, at 8:20 AM, Stephen Hemminger <step...@networkplumber.org> 
> wrote:
> 
> 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.

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