Re: [dpdk-dev] [PATCH] gpudev: introduce memory API

[Jerin Jacob <jerinjacobk@gmail.com>]

On Fri, Jun 4, 2021 at 6:25 PM Thomas Monjalon <thomas@monjalon.net> wrote:
>
> 03/06/2021 13:38, Jerin Jacob:
> > On Thu, Jun 3, 2021 at 4:00 PM Thomas Monjalon <thomas@monjalon.net> wrote:
> > > 03/06/2021 12:04, Jerin Jacob:
> > > > On Thu, Jun 3, 2021 at 3:06 PM Thomas Monjalon <thomas@monjalon.net> wrote:
> > > > > 03/06/2021 11:20, Jerin Jacob:
> > > > > > The device needs have a queue kind of structure
> > > > > > and it is mapping to core to have a notion of configure. queue_setup,
> > > > > > start and stop etc
> > > > >
> > > > > Why is it a requirement to call it a device API?
> > > >
> > > > Then we need to define what needs to call as device library vs library and how?
> > > > Why mempool is not called a  device library vs library?
> > >
> > > My view is simple:
> > > if it has drivers, it is a device API, except bus and mempool libs.
> >
> > rte_secuity has drivers but it is not called a device library.
>
> rte_security is a monster beast :)
> Yes it has rte_security_ops implemented in net and crypto drivers,
> but it is an API extension only, there is no driver dedicated to security.
>
> > > About mempool, it started as a standard lib and got extended for HW support.
> >
> > Yes. We did not change to device library as it was fundamentally
> > different than another DPDK deices
> > when we added the device support.
> >
> > > > and why all
> > > > other device library has a common structure like queues and
> > > > it binding core etc. I tried to explain above the similar attributes
> > > > for dpdk device libraries[1] which I think, it a requirement so
> > > > that the end user will have familiarity with device libraries rather
> > > > than each one has separate General guidelines and principles.
> > > >
> > > > I think, it is more TB discussion topic and decides on this because I
> > > > don't see in technical issue in calling it a library.
> > >
> > > The naming is just a choice.
> >
> > Not sure.
> >
> > > Yesterday morning it was called lib/gpu/
> > > and in the evening it was renamed lib/gpudev/
> > > so no technical issue :)
> > >
> > > But the design of the API with queues or other paradigm
> > > is something I would like to discuss here.
> >
> > Yeah, That is important. IMO, That defines what needs to be a device library.
> >
> > > Note: there was no intent to publish GPU processing control
> > > in DPDK 21.08. We want to focus on GPU memory in 21.08,
> > > but I understand it is a key decision in the big picture.
> >
> > if the scope is only memory allocation, IMO, it is better to make a library.
>
> No it is only the first step.
>
> > > What would be your need and would you design such API?
> >
> > For me, there is no need for gpu library(as of now). May GPU consumers
> > can define what they need to control using the library.
>
> We need to integrate GPU processing workload in the DPDK workflow
> as a generic API.
> There could be 2 modes:
>         - queue of tasks
>         - tasks in an infinite loop
> In both modes, we could get completion notifications
> with an interrupt/callback or by polling a shared memory.


OK. If we have enqeue/dequeue kind operation and with queue model then it
makes sense to have a device model. It was not there in your initial
patch, but if we are adding
in the future then it OK.



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