RE: [PATCH v2 2/2] ethdev: introduce the PHY affinity field in Tx queue API

["Jiawei(Jonny) Wang" <jiaweiw@nvidia.com>]

Hi,

> -----Original Message-----
> From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
> Subject: Re: [PATCH v2 2/2] ethdev: introduce the PHY affinity field in Tx queue
> API
> 
> On 1/30/23 20:00, Jiawei Wang wrote:
> > For the multiple hardware ports connect to a single DPDK port
> > (mhpsdp), the previous patch introduces the new rte flow item to match
> > the phy affinity of the received packets.
> >
> > This patch adds the tx_phy_affinity setting in Tx queue API, the
> > affinity
> 
> "This patch adds" -> "Add ..."
> 
OK,  will change to 'Add the tx_phy_affinity...."

> > value reflects packets be sent to which hardware port.
> > Value 0 is no affinity and traffic will be routed between different
> > physical ports,
> 
> Who will it be routed?
> 

Assume there's two slave physical port bonded and DPDK attached the bond master bond,
The packets can be sent from first physical port or second physical port, it depends on the PMD
Driver and low level 'routing' selection.

> > if 0 is disabled then try to match on phy_affinity 0 will result in an
> > error.
> 
> Why are you talking about matching here?
> 

Previous patch we mentioned the same phy affinity can be used to handled the packet on same hardware
Port, so if 0 is no affinity then match it should report error.

> >
> > Adds the new tx_phy_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) phy_affinity (value)
> >
> > For example, there're two hardware ports 0 and 1 connected to a single
> > DPDK port (port id 0), and phy_affinity 1 stood for hardware port 0
> > and phy_affinity 2 stood for hardware port 1, used the below command
> > to config tx phy affinity for per Tx Queue:
> >          port config 0 txq 0 phy_affinity 1
> >          port config 0 txq 1 phy_affinity 1
> >          port config 0 txq 2 phy_affinity 2
> >          port config 0 txq 3 phy_affinity 2
> >
> > These commands config the TxQ index 0 and TxQ index 1 with phy
> > affinity 1, uses TxQ 0 or TxQ 1 send packets, these packets will be
> > sent from the hardware port 0, and similar with hardware port 1 if
> > sending packets with TxQ 2 or TxQ 3.
> 
> Frankly speaking I dislike it. Why do we need to expose it on generic ethdev
> layer? IMHO dynamic mbuf field would be a better solution to control Tx
> routing to a specific PHY port.
> 

OK, the phy affinity is not part of packet information(like timestamp).
And second, the phy affinity is Queue layer, that is, the phy affinity value 
should keep the same behavior per Queue. 
After the TxQ was created, the packets should be sent the same physical port
If using the same TxQ index.  

> IMHO, we definitely need dev_info information about a number of physical
> ports behind. Advertising value greater than 0 should mean that PMD supports
> corresponding mbuf dynamic field to contol ongoing physical port on Tx (or
> should just reject packets on prepare which try to specify outgoing phy port
> otherwise). In the same way the information may be provided on Rx.
> 

See above, I think phy affinity is Queue level not for each packet.

> I'm OK to have 0 as no phy affinity value and greater than zero as specified phy
> affinity. I.e. no dynamic flag is required.
> 

Thanks for agreement.

> Also I think that order of patches should be different.
> We should start from a patch which provides dev_info and flow API matching
> and action should be in later patch.
>

OK.
 
> >
> > Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
> 
> [snip]