[ovs-dev] OvS DPDK vector pmd drivers

[Ravi Kerur]

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?

Thanks,
Ravi



> William
> >
> > Currently I use descriptors(4096), queues(2) and offloads disabled for
> > ports so would like to know what configuration changes I need to do to
> > switch between processing types?
> >
> > Thanks,
> > Ravi
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