[RFC 2/5] ethdev: introduce the affinity field in Tx queue API

[Jiawei(Jonny) Wang]

Hi,

> 18/01/2023 15:44, Jiawei(Jonny) Wang:
> > > 21/12/2022 11:29, Jiawei Wang:
> > > > For the multiple hardware ports connect to a single DPDK port
> > > > (mhpsdp), the previous patch introduces the new rte flow item to
> > > > match the port affinity of the received packets.
> > > >
> > > > This patch adds the tx_affinity setting in Tx queue API, the
> > > > affinity value reflects packets be sent to which hardware port.
> > >
> > > I think "affinity" means we would like packet to be sent on a
> > > specific hardware port, but it is not mandatory.
> > > Is it the meaning you want? Or should it be a mandatory port?
> >
> > Right, it's optional setting not mandatory.
> 
> I think there is a misunderstanding.
> I mean that "affinity" with port 0 may suggest that we try to send to port 0 but
> sometimes the packet will be sent to port 1.
>
> And I think you want the packet to be always sent to port 0 if affinity is 0, right?
>

These packets should be always sent to port 0 if 'affinity' be set with hardware port 0.
'affinity is 0' -> 0 means that no affinity be set and traffic should be kept the same behavior
as before, for example, routing between different hardware ports.
 
> If yes, I think the word "affinity" does not convey the right idea.
> And again, the naming should give the idea that we are talking about multiple
> ports merged in one DPDK port.
> 

OK, how about 'tx_mhpsdp_hwport? 
'mhpsdp' as mentioned before, 'hwport' means for one 'hardware port'.

> > > > Adds the new tx_affinity field into the padding hole of
> > > > rte_eth_txconf structure, the size of rte_eth_txconf keeps the
> > > > same. Adds a suppress type for structure change in the ABI check file.
> > > >
> > > > This patch adds the testpmd command line:
> > > > testpmd> port config (port_id) txq (queue_id) affinity (value)
> > > >
> > > > For example, there're two hardware ports connects to a single DPDK
> > >
> > > connects -> connected
> >
> > OK, will fix in next version.
> >
> > > > port (port id 0), and affinity 1 stood for hard port 1 and
> > > > affinity
> > > > 2 stood for hardware port 2, used the below command to config tx
> > > > affinity for each TxQ:
> > > > 	port config 0 txq 0 affinity 1
> > > > 	port config 0 txq 1 affinity 1
> > > > 	port config 0 txq 2 affinity 2
> > > > 	port config 0 txq 3 affinity 2
> > > >
> > > > These commands config the TxQ index 0 and TxQ index 1 with
> > > > affinity 1, uses TxQ 0 or TxQ 1 send packets, these packets will
> > > > be sent from the hardware port 1, and similar with hardware port 2
> > > > if sending packets with TxQ 2 or TxQ 3.
> > >
> > > [...]
> > > > @@ -212,6 +212,10 @@ API Changes
> > > > +* ethdev: added a new field:
> > > > +
> > > > +  - Tx affinity per-queue ``rte_eth_txconf.tx_affinity``
> > >
> > > Adding a new field is not an API change because existing
> > > applications don't need to update their code if they don't care this new field.
> > > I think you can remove this note.
> >
> > OK, will remove in next version.
> >
> > > > --- a/lib/ethdev/rte_ethdev.h
> > > > +++ b/lib/ethdev/rte_ethdev.h
> > > > @@ -1138,6 +1138,7 @@ struct rte_eth_txconf {
> > > >  				      less free descriptors than this value. */
> > > >
> > > >  	uint8_t tx_deferred_start; /**< Do not start queue with
> > > > rte_eth_dev_start(). */
> > > > +	uint8_t tx_affinity; /**< Drives the setting of affinity per-queue.
> > > > +*/
> > >
> > > Why "Drives"? It is the setting, right?
> > > rte_eth_txconf is per-queue so no need to repeat.
> > > I think a good comment here would be to mention it is a physical
> > > port index for mhpsdp.
> > > Another good comment would be to specify how ports are numbered.
> >
> > OK, will update the comment for this new setting.
> >
> > Thanks.
> 
>