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

[Jerin Jacob <jerinjacobk@gmail.com>]

On Thu, Jun 3, 2021 at 2:23 PM Thomas Monjalon <thomas@monjalon.net> wrote:
>
> 03/06/2021 10:47, Jerin Jacob:
> > On Thu, Jun 3, 2021 at 2:13 PM Thomas Monjalon <thomas@monjalon.net> wrote:
> > >
> > > 03/06/2021 10:41, Jerin Jacob:
> > > > On Thu, Jun 3, 2021 at 1:58 PM Thomas Monjalon <thomas@monjalon.net> wrote:
> > > > >
> > > > > 03/06/2021 09:47, Jerin Jacob:
> > > > > > On Thu, Jun 3, 2021 at 2:05 AM Thomas Monjalon <thomas@monjalon.net> wrote:
> > > > > > > --- a/doc/api/doxy-api-index.md
> > > > > > > +++ b/doc/api/doxy-api-index.md
> > > > > > > @@ -21,6 +21,7 @@ The public API headers are grouped by topics:
> > > > > > >    [compressdev]        (@ref rte_compressdev.h),
> > > > > > >    [compress]           (@ref rte_comp.h),
> > > > > > >    [regexdev]           (@ref rte_regexdev.h),
> > > > > > > +  [gpudev]             (@ref rte_gpudev.h),
> > > > > >
> > > > > > Since this device does not have a queue etc? Shouldn't make it a
> > > > > > library like mempool with vendor-defined ops?
> > > > > > Any specific reason for making it a device? The reason why I am asking
> > > > > > this is, as other DPDK devices as symmetry in queue(s), configure,
> > > > > > start, stop operation etc.
> > > > > >
> > > > > >
> > > > > > > +
> > > > > > > +struct rte_gpu_dev {
> > > > > > > +       /* Backing device. */
> > > > > > > +       struct rte_device *device;
> > > > > >
> > > > > > See above?
> > > > >
> > > > > There is a PCI device probed.
> > > > > I don't understand why it would not be represented as a device.
> > > >
> > > > All other DPDK device has symmetry in structures like queue and
> > > > symmetry in operation like it has configure, start, stop etc.
> > > > This one seems more like mempool to me all we want set of
> > > > vendor-defined ops. So any justification on
> > > > make it a device ? why not like mempool library?
> > > > (driver/mempool/octeontx2 Mempool HW is also PCI device, but
> > > > we don't take device path for mempool. So I would like to understand
> > > > any technical reason for making it a device).
> > >
> > > I don't understand what you mean by "symmetry".
> >
> > The common attributes. or similarity
>
> The common attributes of a device are:
>         - driver
>         - bus
>         - devargs
> We have these attributes for a GPU.

Yes. Those are attributes of rte_device. That does not mean and
library can not use rte_device.(mempool library driver is using
rte_device which is backed by PCI)
In terms of similarity, all other device libraries(not devices) have
queue, enqueue() and dequeue() kind of scheme
in ethdev, cryptodev, compressdev, eventdev, bbdev, rawdev. regexdev.
i.e existing DPDK device libraries,
This one des not have have that, So question why to call it libgpudev vs libgpu.

The functions you have are memory allocation etc. That's more of a
library candidate.

>
> About configure/start/stop usual functions,
> I think we'll have something similar in the second step

Do you think or it will be there?. I think, it is import decision. 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
Something similar to
http://code.dpdk.org/dpdk/v21.05/source/lib/regexdev/rte_regexdev.h#L27
Could you share how "running tasks" translates to the above scheme
like other her dpdk device libraries?



> for running tasks.
>
>