[dpdk-dev] i40e queues per VF

[Thomas Monjalon <thomas.monjalon@6wind.com>]

Hi,

When reading the documentation, it is not easy to understand
the capability of i40evf for the number of queues.

First, please could you explain why we need a build-time config option?
In the doc, there is neither justification nor tuning guidelines:

http://dpdk.org/doc/guides/nics/i40e.html#config-file-options
"
CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_PF (default 64)
Number of queues reserved for PF.
CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_VF (default 4)
Number of queues reserved for each SR-IOV VF.
"

I feel these are hard limits and should be some constants in the code,
not some build configuration options.

The other doc to look at is:
http://dpdk.org/doc/guides/nics/intel_vf.html#intel-fortville-10-40-gigabit-ethernet-controller-vf-infrastructure
"
Each VF can have a maximum of 16 queue pairs.
"

Do we agree that a queue pair is 1 Rx queue / 1 Tx queue?
Note: the concept of queue pairs in Intel VF should be explained somewhere.

Below, a different limitation is given:
"
The available queue number(at most 4) per VF depends on the total number
of pool, which is determined by the max number of VF at PF initialization
stage and the number of queue specified in config
"

So what is the real maximum of queue pairs? 4 or 16?
The datasheet talks about 16 queues. Is it 8 pairs?

Is there something to configure the number of queues when creating VF
with the kernel driver?