[dpdk-dev] [PATCH v2 6/6] app/testpmd: adjust ethdev port ownership

Matan Azrad matan at mellanox.com
Mon Jan 8 14:55:52 CET 2018


Hi Gaetan

From: Gaëtan Rivet, Monday, January 8, 2018 3:30 PM
> On Mon, Jan 08, 2018 at 12:30:19PM +0000, Matan Azrad wrote:
> >
> >
> > From: Gaëtan Rivet, Monday, January 8, 2018 1:40 PM
> > > Hi Matan,
> > >
> > > On Sun, Jan 07, 2018 at 09:45:51AM +0000, Matan Azrad wrote:
> > > > Testpmd should not use ethdev ports which are managed by other
> > > > DPDK entities.
> > > >
> > > > Set Testpmd ownership to each port which is not used by other
> > > > entity and prevent any usage of ethdev ports which are not owned by
> Testpmd.
> > > >
> > >
> > > This patch should not be necessary.
> > >
> > > Ideally, your API evolution should not impact the default case. As
> > > such, the default iterator RTE_ETH_FOREACH_DEV should still be used in
> testpmd.
> > >
> > Why? We want to adjust testpmd to the port ownership.
> >
> 
> This adjustment should be seamless for existing application.
> 
> > > RTE_ETH_FOREACH_DEV should call
> RTE_ETH_FOREACH_DEV_OWNED_BY, with
> > > the default owner (meaning that it would thus iterate on the
> > > application-owned set of device).
> > >
> >
> > It will break the API (we already talked about it).
> > There is not any default owner:
> > Any DPDK entity includes applications must to allocate an owner ID and use
> it to own the ports they wants to use.
> > The application can include more than 1 owner depends on the user needs.
> > Each DPDK entity which can synchronize all its port usage can be a valid
> DPDK entity for the ownership mechanism.
> >
> 
> That's the point of my remark: you did not include a default owner.
> I think there should be one, and that all ports should pertain to this default
> owner by default when created.
> 
> This would not prevent a user or application from adding new owners specific
> to their use and specialize ports if need be.
> 
> However, for other applications that do not care for this specialization, they
> should run with the current API and avoid the ports that are configured by
> other third parties.
> 

RTE_ETH_FOREACH_DEV means iterate over all devices and should stay as is in my opinion.
I understand your concern about changes in current application,
But your "default" suggestion will cause to "non-default" applications to reset all the default owners and will complicate them and hurt semantics.

> I'm thinking about applications already written that would be used with fail-
> safe ports: they would use RTE_ETH_FOREACH_DEV, and would thus iterate
> over every ports, including those owned by the fail-safe, unless they start
> following the new API.
> 

They should start, it is really not complicated.
What's about application which use count=rte_eth_dev_count and iterate over all ports from 0 to count-1?
We cannot save all the wrong application options.

> This is unnecessary: adding a default owner for all created ports and
> redefining RTE_ETH_FOREACH_DEV as follow
> 
> #define RTE_ETH_FOREACH_DEV(i)
>         RTE_ETH_FOREACH_DEV_OWNED_BY(i, RTE_ETH_DEFAULT_OWNER)
> 
> Is simple enough and will simplify the work of DPDK users. Moreover, it
> would make fail-safe compatible with all applications using
> RTE_ETH_FOREACH_DEV without additional evolution. It would actually make
> any code using your API supported by those same applications, which I think
> would help its adoption.
> 

Will break API, will hurt semantic of FOREACH , and will complicate ownership care applications as I wrote above.

> --
> Gaëtan Rivet
> 6WIND


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