Issue is because of tap_mp_req_on_rxtx() sending msg.num_fds more than RTE_MP_MAX_FD_NUM fds for queues > 4. Looks like these tap driver changes are added as part of the below patch http://patches.dpdk.org/project/dpdk/patch/20220121042944.23929-1-kumaraparamesh92@gmail.com/ On Mon, Jun 26, 2023 at 3:53 PM Nageswara Rao wrote: > Yes, we are using vdev_netvsc. Native netvsc PMD we are observing issues > in enabling multiple queues. > Though we have 6 DPDK cores, unable to configure more than 4 queues. > > On Mon, Jun 26, 2023 at 12:18 AM Stephen Hemminger < > stephen@networkplumber.org> wrote: > >> On Thu, 22 Jun 2023 22:06:10 +0530 >> Nageswara Rao wrote: >> >> > Hi All, >> > >> > We are observing the following issue with DPDK22.11. We didn’t find any >> > upstream patches for this issue on the DPDK github. Is there any known >> > issue, please let us know. >> > >> > >> > >> > *Issue:* >> > >> > On Azure platform, we are unable to configure more than 4 queues. When >> we >> > try to configure more than 4 queues its failing with “EAL: Cannot send >> more >> > than 8 FDs” error. >> > >> > Here I am pasting the working and failing testpmd logs. >> > >> > Please note that this issue is not observed in DPDK 21.11. >> > >> >> You should be using the native netvsc PMD, not the >> vdev_netvsc,failsafe,tap kludge. >> >> I don't work on Azure any more but I suspect the issue is that the default >> in the kernel for TAP is for the number of queues == number of cores. >> >> You aren't going to see any real benefit from having more queues than >> the number of DPDK cores. >> >>