Re: [PATCH v4 1/2] gpudev: expose GPU memory to CPU

[Elena Agostini <eagostini@nvidia.com>]

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> From: Wang, Haiyue <haiyue.wang@intel.com>
> Date: Thursday, 27 January 2022 at 07:56
> To: Elena Agostini <eagostini@nvidia.com>, dev@dpdk.org <dev@dpdk.org>
> Subject: RE: [PATCH v4 1/2] gpudev: expose GPU memory to CPU
> External email: Use caution opening links or attachments
>
>
> > -----Original Message-----
> > From: eagostini@nvidia.com <eagostini@nvidia.com>
> > Sent: Thursday, January 27, 2022 11:47
> > To: dev@dpdk.org
> > Cc: Elena Agostini <eagostini@nvidia.com>
> > Subject: [PATCH v4 1/2] gpudev: expose GPU memory to CPU
> >
> > From: Elena Agostini <eagostini@nvidia.com>
> >
> > Enable the possibility to expose a GPU memory area and make it
> > accessible from the CPU.
> >
> > GPU memory has to be allocated via rte_gpu_mem_alloc().
> >
> > This patch allows the gpudev library to map (and unmap),
> > through the GPU driver, a chunk of GPU memory and to return
> > a memory pointer usable by the CPU to access the GPU memory area.
> >
> > Signed-off-by: Elena Agostini <eagostini@nvidia.com>
> > ---
> >  doc/guides/prog_guide/gpudev.rst |  9 +++++
> >  drivers/gpu/cuda/cuda.c          |  2 ++
> >  lib/gpudev/gpudev.c              | 61 ++++++++++++++++++++++++++++++++
> >  lib/gpudev/gpudev_driver.h       |  6 ++++
> >  lib/gpudev/rte_gpudev.h          | 49 +++++++++++++++++++++++++
> >  lib/gpudev/version.map           |  2 ++
> >  6 files changed, 129 insertions(+)
> >
>
>
> > +__rte_experimental
> > +void *rte_gpu_mem_cpu_map(int16_t dev_id, size_t size, void *ptr);
>
> How about add some direction words like "to/from" to make it straightforward ?
>
> For this: rte_gpu_mem_map_to_cpu ?
>
> > +__rte_experimental
> > +int rte_gpu_mem_cpu_unmap(int16_t dev_id, void *ptr);
> > +
>
> And rte_gpu_mem_unmap_to_cpu ?
>
> >  };
> > --
> > 2.17.1

Motivation behind the name is to be compliant with
rte_*_dma_map/unmap() functions where the entity comes first
(DMA) and the action later (map/unmap).

I think your proposal is more readable but it's also too
verbose for an API (map_to_cpu/unmap_from_cpu).

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