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

[Thomas Monjalon <thomas@monjalon.net>]

04/06/2021 13:07, Wang, Haiyue:
> > From: Elena Agostini <eagostini@nvidia.com>
> > +typedef int (*gpu_malloc_t)(struct rte_gpu_dev *dev, size_t size, void **ptr);
> > +typedef int (*gpu_free_t)(struct rte_gpu_dev *dev, void *ptr);
> > +
[...]
> > +	/* FUNCTION: Allocate memory on the GPU. */
> > +	gpu_malloc_t gpu_malloc;
> > +	/* FUNCTION: Allocate memory on the CPU visible from the GPU. */
> > +	gpu_malloc_t gpu_malloc_visible;
> > +	/* FUNCTION: Free allocated memory on the GPU. */
> > +	gpu_free_t gpu_free;
> 
> 
> I'm wondering that we can define the malloc type as:
> 
> typedef int (*gpu_malloc_t)(struct rte_gpu_dev *dev, size_t size, void **ptr,
> 					unsigned int flags)
> 
> #define RTE_GPU_MALLOC_F_CPU_VISIBLE 0x01u --> gpu_malloc_visible
> 
> Then only one malloc function member is needed, paired with 'gpu_free'.
[...]
> > +int rte_gpu_malloc(uint16_t gpu_id, size_t size, void **ptr);
[...]
> > +int rte_gpu_malloc_visible(uint16_t gpu_id, size_t size, void **ptr);
> 
> Then 'rte_gpu_malloc_visible' is no needed, and the new call is:
> 
> rte_gpu_malloc(uint16_t gpu_id, size_t size, void **ptr, RTE_GPU_MALLOC_F_CPU_VISIBLE).
> 
> Also, we can define more flags for feature extension. ;-)

Yes it is a good idea.

Another question is about the function rte_gpu_free().
How do we recognize that a memory chunk is from the CPU and GPU visible,
or just from GPU?