[dpdk-dev] : rx_no_dma_resources starts climbing on Intel 82599 SR-IOV ports

[Yan Fridland <yan@asocsnetworks.com>]

Hello All,

Perhaps you can shade some light on an interesting problem we have.

I am working with Intel 82599 NICs in a SR-IOV mode. After several hours of running traffic we checked port statistics on a host and saw that the counter rx_no_dma_resources began climbing on some ports.
At that exact time the VM applications connected to that ports showed packet loss and crashed.

First question, do you have a clue what is it related to? (I run the same application on all ports but not all of them experience such thing)

After digging a bit I saw that the RX descriptors ring size on the host ports was defined to 256 out of 4096 possible (I used ehttool -G). I know that in DPDK I define each port's RX queue to be 256 descriptors, but this is done per VM port which means per VF of the physical NIC.


  *   Do you know what is the relationship, if any, between the number of descriptors defined in DPDK per VM port (VF on host) using rte_eth_rx_queue_setup () and the number of descriptors defined on Host per physical port (using ethtool -g <dev> rx <desc num>) ?
Seems to me that they don't effect one another but perhaps I am wrong.


Thanks,
Yan