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

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