Re: [PATCH net-next] sfc: reduce the number of requested xdp ev queues

Edward Cree
2020-12-16T23:13:12Z

On 16/12/2020 08:45, Jesper Dangaard Brouer wrote:
> So, what I hear is that this fix is just pampering over the real issue.
Yes, it is, but it's better than nothing in the meantime while we work
out the complete fix.

> I suggest that you/we detect the situation, and have a code path that
> will take a lock (per 16 packets bulk) and solve the issue.
Imho that would _also_ paper over the issue, because it would mean the
system degraded to a lower performance mode of operation, while still
appearing to support XDP_TX. I think that that in general should not
happen unless there is a way for the user to determine at runtime
whether it has/should happen. Perhaps Marek's new XDP feature flags
could include a "tx-lockless" flag to indicate this?

-ed