On Tue, 8 Feb 2022 18:00:27 +0000
Ferruh Yigit <ferruh.yi...@intel.com> wrote:
> On 2/8/2022 5:45 PM, Stephen Hemminger wrote:
> > On Tue, 8 Feb 2022 13:48:00 +0000
> > Ciara Loftus <ciara.lof...@intel.com> wrote:
> >
> >> +- **Secondary Processes**
> >> +
> >> + Rx and Tx are not supported for secondary processes due to the
> >> single-producer
> >> + single-consumer nature of the AF_XDP rings. However other operations
> >> including
> >> + statistics retrieval are permitted.
> >> + The maximum number of queues permitted for PMDs operating in this model
> >> is 8
> >> + as this is the maximum number of fds that can be sent through the IPC
> >> APIs as
> >> + defined by RTE_MP_MAX_FD_NUM.
> >> +
> >
> > This seems like a restriction that is true for most devices in DPDK.
> > Most other devices also have restriction that on queues;
> > the hardware descriptor ring can only be used by one thread at a time.
> > Is this different with AF_XDP?
>
> I asked the same on v2 :) and Ciara explained the reason, it is on v2
> discussion thread.
The wording of the message is what confused me.
It would be better to change:
due to the single-producer single-consumer nature of the AF_XDP rings
to
due to memory mapping of the AF_XDP rings being assigned by the kernel
in the primary process only.
