Re: [dpdk-dev] [PATCH 00/39] adding eventmode helper library

[Anoob Joseph <anoobj@marvell.com>]

Hi Jerin, Mattias,

Please see inline.

Thanks,
Anoob

> -----Original Message-----
> From: Jerin Jacob Kollanukkaran
> Sent: Tuesday, June 25, 2019 4:03 PM
> To: Anoob Joseph <anoobj@marvell.com>; Mattias Rönnblom
> <mattias.ronnblom@ericsson.com>; Nikhil Rao <nikhil.rao@intel.com>; Erik
> Gabriel Carrillo <erik.g.carrillo@intel.com>; Abhinandan Gujjar
> <abhinandan.gujjar@intel.com>; Bruce Richardson
> <bruce.richardson@intel.com>; Pablo de Lara
> <pablo.de.lara.guarch@intel.com>
> Cc: Narayana Prasad Raju Athreya <pathreya@marvell.com>; dev@dpdk.org;
> Lukas Bartosik <lbartosik@marvell.com>; Pavan Nikhilesh Bhagavatula
> <pbhagavatula@marvell.com>; Hemant Agrawal
> <hemant.agrawal@nxp.com>; Nipun Gupta <nipun.gupta@nxp.com>; Harry
> van Haaren <harry.van.haaren@intel.com>; Liang Ma
> <liang.j.ma@intel.com>
> Subject: RE: [dpdk-dev] Re: [PATCH 00/39] adding eventmode helper library
> 
> > -----Original Message-----
> > From: Anoob Joseph
> > Sent: Thursday, June 20, 2019 9:15 AM
> > To: Mattias Rönnblom <mattias.ronnblom@ericsson.com>; Jerin Jacob
> > Kollanukkaran <jerinj@marvell.com>; Nikhil Rao <nikhil.rao@intel.com>;
> > Erik Gabriel Carrillo <erik.g.carrillo@intel.com>; Abhinandan Gujjar
> > <abhinandan.gujjar@intel.com>; Bruce Richardson
> > <bruce.richardson@intel.com>; Pablo de Lara
> > <pablo.de.lara.guarch@intel.com>
> > Cc: Narayana Prasad Raju Athreya <pathreya@marvell.com>;
> dev@dpdk.org;
> > Lukas Bartosik <lbartosik@marvell.com>; Pavan Nikhilesh Bhagavatula
> > <pbhagavatula@marvell.com>; Hemant Agrawal
> <hemant.agrawal@nxp.com>;
> > Nipun Gupta <nipun.gupta@nxp.com>; Harry van Haaren
> > <harry.van.haaren@intel.com>; Liang Ma <liang.j.ma@intel.com>
> > Subject: RE: [dpdk-dev] [EXT] Re: [PATCH 00/39] adding eventmode
> > helper library
> > > However, the flexibility and many of the parameters are there for a
> > > reason (those there aren't should be deprecated). I would expect a
> > > real-world application to tweak quite a few of them. I know our
> > > applications
> > do.
> > >
> > > I worry I have is that if you put eventmode (in its current form)
> > > forward as a generic framework, applications might start using it,
> > > only to realize it's not flexible enough, and then eventmode is just
> > > an extra layer, increasing rather than reducing complexity. Or even
> > > worse, the application's developers are forced to do a big-bang
> > > switch over to using the event and ethernet device APIs directly, in
> > > case they can't patch DPDK to work around the eventmode-
> > > assumption-that-
> > didn't-hold-for-them.
> > >
> > > You could always add flexibility to the framework (as you encounter
> > > a need for it), but then it will grow in complexity as well.
> > >
> > > A less ambitious approach would be to instead do a properly
> > > modularized, non-trivial eventdev example application, for the
> > > applications to start off from, instead of a generic library.
> > >
> > > I would expect it to be very difficult to design a truly generic
> > > application framework for eventdev-based applications. Such a
> > > framework would tie everything that's needed in a non-trivial
> > > application together. If successful, it would be a huge step toward
> > > making DPDK an operating system for packet processing applications.
> >
> > [Anoob] The idea here is not to deprecate any event dev APIs. I do
> > agree that all the configuration exposed by eventdev & adapters are
> > required for various requirements in the real world applications. But
> > the requirement to understand & use all this configuration is making
> > the applications complicated and causes significant effort from anyone who
> would want to get started with event mode.
> > The idea of helper is to allow an easy framework for applications to
> > get started with eventmode, and then use various options from C/L or
> > config file (both
> > planned) to override the configuration as required. DPDK has
> > components like crypto-scheduler which abstracts lot of configuration
> > and simplify usage from application's perspective. This effort is on similar
> lines.
> >
> > My patchset is a followup to http://patches.dpdk.org/patch/37955 ,
> > wherein the approach of introducing a helper library for event mode
> > was mooted. The initial patch proposed additions in one application,
> > and that involved huge code additions just for doing the configuration.
> >
> > The helper library will be experimental while we add event-mode
> > support for other applications like l3fwd & ipsec-secgw. I expect the
> > helper library to be complete over the course of those applications also
> using the helper library.
> 
> 
> I have only concern about moving this as library inside eventdev that till we
> have mature version of helper library the eventdev library ABI will not
> stable(i.e .so file version needs to be incremented as when a change
> needed). Which align with Mattias thoughts for some other reason:. How
> about moving this code to
> 1) example/common or
> 2) to specific application itself, once at least two applications starts using it
> then move to Eventdev library.
> 
> Thoughts?

[Anoob] Either location is not a problem if there is a consensus. Earlier the suggestion was to move it to library (when the patch was submitted with changes added in app).

Since there are other comments, which are being addressed, I would like to send the next series with the current layout itself. And when we have an agreement on the location to be used, I'll make the changes. Is that fine?

> 
> 
> 
> 
> >
> > >
> > > What event devices have you tested with?
> >
> > [Anoob] Eventmode helper is tested with the following combinations,
> >     1. event-octeontx event PMD & nicvf eth PMD
> >     2. event-octeontx event PMD & eth-octeontx eth PMD