Re: [dpdk-dev] [dpdk-techboard] DPDK ABI/API Stability

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 8 Apr 2019 16:38:55 +0200
David Marchand <david.marchand@redhat.com> wrote:

> On Mon, Apr 8, 2019 at 4:03 PM Burakov, Anatoly <anatoly.burakov@intel.com>
> wrote:
> 
> > On 08-Apr-19 2:58 PM, David Marchand wrote:  
> > > On Mon, Apr 8, 2019 at 3:39 PM Burakov, Anatoly
> > > <anatoly.burakov@intel.com <mailto:anatoly.burakov@intel.com>> wrote:
> > >
> > >     As a concrete proposal, my number one dream would be to see
> > >     multiprocess
> > >     gone. I also recall desire for "DPDK to be more lightweight", and i
> > >     maintain that DPDK *cannot* be lightweight if we are to support
> > >     multiprocess - we can have one or the other, but not both. However,
> > >     realistically, i don't think dropping multiprocess is ever going to
> > >     happen - not only it is too entrenched in DPDK use cases, it is
> > >     actually
> > >     quite useful despite its flaws.
> > >
> > >
> > > Well, honestly, I'd like to hear about this.
> > > What are the real usecases for multi process support?
> > > Do we have even a single opensource project that uses it?
> > >  
> >
> > I'm aware of a few closed source usages of multiprocess. I also think
> > current versions of collectd rely on secondary process (there's been a
> > Telemetry API added to avoid that, but AFAIK the support for Telemetry
> > is not upstream in collectd yet), and so do/would any dump-style
> > applications - in fact, we ourselves include one such application in our
> > codebase (pdump, proc-info, etc.).
> >  
> 
> Sorry, I don't want to highjack this thread, I can start a separate thread
> if people feel like it.
> If we go with stabilisation, we must be careful that we want to support the
> features.
> 
> So about multiprocess, again, in those closed source projects you know of,
> what are the usecases?
> 
> For what we provide in dpdk pdump, proc-info, referring to oneself is not
> that convincing to me as I don't use those tools.
> 
> I don't see what we could not achieve the same with a control thread
> running in the dpdk process and handling commands.
> It would be open to the outside via a more standard channel, like a UNIX
> socket or something like this.
> If we need to declare a dynamic channel, it can be constructed as an
> extension of the existing standard channel: we can open something like a
> POSIX shm and push things in it.
> Was this explored ?
> 
> 

Yes, there are several closed source applications using multi-process.
But the problem with that is no one tests with all the drivers, api's and
configurations in DPDK.