[ovs-dev] OvS DPDK vector pmd drivers

[William Tu]

On Sat, Apr 11, 2020 at 10:18 AM Ravi Kerur <rkerur at gmail.com> wrote:
>
> Hi William,
>
> On Fri, Apr 10, 2020 at 7:06 AM William Tu <u9012063 at gmail.com> wrote:
>>
>> On Thu, Apr 09, 2020 at 02:14:26PM -0700, Ravi Kerur wrote:
>> > Hi OvS DPDK team,
>> >
>> > I am looking at ixgbe_set_rx_function and ixgbe_set_tx_function and would
>> > like to enable vectorized packet handling. Looking at ixgbe_set_rx_function
>>
>> Do you mean this "27.1. Vector PMD for IXGBE"?
>> https://doc.dpdk.org/guides/nics/ixgbe.html
>>
>
> Yes, from the documentation p.o.v this is what I am referring to.
>
>> > I see that it depends on device configuration and other parameters like
>> > descriptors, burst sze to enable vectorized Rx and Tx. How do I check which
>> > Tx and Rx OvS is using for processing?
>>
>> Hi Ravi,
>>
>> Do you mean whether OVS-DPDK uses this:
>>
>>         /*
>>          * Set the non-LRO scattered callback: there are Vector and
>>          * single allocation versions.
>>          */
>>         if (adapter->rx_vec_allowed) {
>>             PMD_INIT_LOG(DEBUG, "Using Vector Scattered Rx "
>>                         "callback (port=%d).",
>>                      dev->data->port_id);
>>
>> I guess if your NIC and CPU support, it should be automatically
>> enabled.
>
>
>  This is one case of Scattered Rx. Code. Which function gets selected depends on variables dev->data->lro, dev->data->scattered_rx, adapter->rx_vec_allowed, adapter->rx_bulk_alloc_allowed. Variables set/unset depends on descriptors, thresholds and other parameters. Similar logic is present for Tx as well. I have both 82599 and x710 NICs to it applies to both IXGBE and I40E drivers.
>
> How do I switch between different Tx and Rx functions in order to select an optimal one? Configurations other than queues/descriptor which can dictate a particular Rx and Tx?
>

Hi Ravi,
I don't think you can do that in OVS, the interface is not exposed to OVS.
Probably you should do it in DPDK source code.
William