[PATCH v6] ethdev: introduce available Rx descriptors threshold

[Thomas Monjalon]

08/06/2022 19:22, Thomas Monjalon:
> 08/06/2022 18:35, Andrew Rybchenko:
> > From: Spike Du <spiked at nvidia.com>
> > 
> > A new event RTE_ETH_EVENT_RX_AVAIL_THRESH should be generated by HW
> > when number of available descriptors in Rx queue goes below the
> > threshold.
> > 
> > The threshold is defined as a percentage of an Rx queue size with valid
> > values from 0 to 99 (inclusive). Zero (default) value disables it.
> > 
> > There is no capability reporting for the feature. Application should
> > simply try to set required threshold value and handle result.
> > 
> > Add testpmd commands to control the threshold:
> >   set port <port_id> rxq <rxq_id> avail_thresh <avail_thresh_num>
> > 
> > Signed-off-by: Spike Du <spiked at nvidia.com>
> > Signed-off-by: Andrew Rybchenko <andrew.rybchenko at oktetlabs.ru>
> > ---
> > v6:
> >     - try to make descriptor shorter and more useful
> >     - refine terminology to use "available descriptors threshold"
> >       everywhere (plural "descriptors")
> >     - fix ethdev API documenation
> >     - define negative return values
> >     - define rules to convert percentage to descriptors number
> >       in drivers
> >     - avoid extra checks in testpmd helper to allow ethdev API
> >       to do its job
> >     - minor fixes in testpmd variables naming
> >     - fix testpmd help to be human oriented
> >     - update testpmd users guide
> >     - add release notes
> 
> What a (more than) review work, thanks a lot for this v6!
> 
> Acked-by: Thomas Monjalon <thomas at monjalon.net>
> 
> With a few minor arrangements,
> applied, thanks.

PS: some ABI exceptions have to be added as discussed in the thread:

+; Ignore ethdev event enum update
+; because new event cannot be received if not registered
+[suppress_type]
+        type_kind = enum
+        changed_enumerators = RTE_ETH_EVENT_MAX
+
+; Ignore fields inserted in cacheline boundary of rte_eth_rxq_info
+; because the struct size is unchanged
+[suppress_type]
+        name = rte_eth_rxq_info
+        has_data_member_inserted_between = {offset_of(rx_buf_size), end}