Re: [dpdk-dev] secondary processes and private data

[Alejandro Lucero <alejandro.lucero@netronome.com>]

Yes, I agree.

On Wed, Sep 26, 2018 at 2:21 PM Thomas Monjalon <thomas@monjalon.net> wrote:

> Hi Alejandro,
>
> 25/09/2018 16:10, Alejandro Lucero:
> > I've a problem when part of device private data needs to be private per
> > process.
>
> It appears we are facing the same issue to support multi-process in tap.
>
> > Current multiprocess support shares device private data between primary
> and
> > secondaries but it is all dependent on a pointer initialized to the same
> > memory address by the multiprocess support code. If there is a
> per-process
> > data, If a secondary process changes it the primary gets affected, and
> the
> > same for additional secondaries which will affect not just the primary
> but
> > other previous secondaries.
>
> Yes, the field rte_eth_dev.data.dev_private is private to the device,
> but shared between processes.
>
> > The solution is to add support for this inside struct rte_eth_dev,
> > something like
> >
> > void *secondary_priv_data;
> >
> > so it is up to the secondaries to use this field if necessary.
>
> I would say it is not only for secondary process.
> What about this name:
>
>         rte_eth_dev.process_private
>
> > NFP PMD creates the required rte_eth_devs specifically, similar to what
> is
> > done inside rte_ethdev.c but adding initialization for an interface
> needed
> > when calling device ethdev_init function. There are other PMDs doing this
> > but none has this requirement for per-process private data.
>
> Actually tap has a per-process requirement for its file descriptors.
>
> > Please, let me know what you think about this change to struct rte_ethdev
> > or if you have a better idea for solving this problem.
>
> I support the idea, but we need to agree on name bikeshedding :-)
>
>
>