[dpdk-dev] [PATCH v3 04/11] mempool: add op to calculate memory size to be allocated

[Burakov, Anatoly]

On 26-Mar-18 5:09 PM, Andrew Rybchenko wrote:
> Size of memory chunk required to populate mempool objects depends
> on how objects are stored in the memory. Different mempool drivers
> may have different requirements and a new operation allows to
> calculate memory size in accordance with driver requirements and
> advertise requirements on minimum memory chunk size and alignment
> in a generic way.
> 
> Bump ABI version since the patch breaks it.
> 
> Suggested-by: Olivier Matz <olivier.matz at 6wind.com>
> Signed-off-by: Andrew Rybchenko <arybchenko at solarflare.com>
> ---

Hi Andrew,

<...>

> -	total_elt_sz = mp->header_size + mp->elt_size + mp->trailer_size;
>   	for (mz_id = 0, n = mp->size; n > 0; mz_id++, n -= ret) {
> -		size = rte_mempool_xmem_size(n, total_elt_sz, pg_shift,
> -						mp->flags);
> +		size_t min_chunk_size;
> +
> +		mem_size = rte_mempool_ops_calc_mem_size(mp, n, pg_shift,
> +				&min_chunk_size, &align);
> +		if (mem_size < 0) {
> +			ret = mem_size;
> +			goto fail;
> +		}
>   
>   		ret = snprintf(mz_name, sizeof(mz_name),
>   			RTE_MEMPOOL_MZ_FORMAT "_%d", mp->name, mz_id);
> @@ -606,7 +600,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
>   			goto fail;
>   		}
>   
> -		mz = rte_memzone_reserve_aligned(mz_name, size,
> +		mz = rte_memzone_reserve_aligned(mz_name, mem_size,
>   			mp->socket_id, mz_flags, align);
>   		/* not enough memory, retry with the biggest zone we have */
>   		if (mz == NULL)
> @@ -617,6 +611,12 @@ rte_mempool_populate_default(struct rte_mempool *mp)
>   			goto fail;
>   		}
>   
> +		if (mz->len < min_chunk_size) {
> +			rte_memzone_free(mz);
> +			ret = -ENOMEM;
> +			goto fail;
> +		}
> +
>   		if (mp->flags & MEMPOOL_F_NO_IOVA_CONTIG)
>   			iova = RTE_BAD_IOVA;

OK by me, but needs to be rebased.

>   		else
> @@ -649,13 +649,14 @@ rte_mempool_populate_default(struct rte_mempool *mp)
>   static size_t
>   get_anon_size(const struct rte_mempool *mp)
>   {
> -	size_t size, total_elt_sz, pg_sz, pg_shift;
> +	size_t size, pg_sz, pg_shift;
> +	size_t min_chunk_size;
> +	size_t align;
>   
>   	pg_sz = getpagesize();

<...>

>   
> +/**
> + * Calculate memory size required to store given number of objects.
> + *
> + * If mempool objects are not required to be IOVA-contiguous
> + * (the flag MEMPOOL_F_NO_IOVA_CONTIG is set), min_chunk_size defines
> + * virtually contiguous chunk size. Otherwise, if mempool objects must
> + * be IOVA-contiguous (the flag MEMPOOL_F_NO_IOVA_CONTIG is clear),
> + * min_chunk_size defines IOVA-contiguous chunk size.
> + *
> + * @param[in] mp
> + *   Pointer to the memory pool.
> + * @param[in] obj_num
> + *   Number of objects.
> + * @param[in] pg_shift
> + *   LOG2 of the physical pages size. If set to 0, ignore page boundaries.
> + * @param[out] min_chunk_size
> + *   Location for minimum size of the memory chunk which may be used to
> + *   store memory pool objects.
> + * @param[out] align
> + *   Location for required memory chunk alignment.
> + * @return
> + *   Required memory size aligned at page boundary.
> + */
> +typedef ssize_t (*rte_mempool_calc_mem_size_t)(const struct rte_mempool *mp,
> +		uint32_t obj_num,  uint32_t pg_shift,
> +		size_t *min_chunk_size, size_t *align);
> +
> +/**
> + * Default way to calculate memory size required to store given number of
> + * objects.
> + *
> + * If page boundaries may be ignored, it is just a product of total
> + * object size including header and trailer and number of objects.
> + * Otherwise, it is a number of pages required to store given number of
> + * objects without crossing page boundary.
> + *
> + * Note that if object size is bigger than page size, then it assumes
> + * that pages are grouped in subsets of physically continuous pages big
> + * enough to store at least one object.
> + *
> + * If mempool driver requires object addresses to be block size aligned
> + * (MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS), space for one extra element is
> + * reserved to be able to meet the requirement.
> + *
> + * Minimum size of memory chunk is either all required space, if
> + * capabilities say that whole memory area must be physically contiguous
> + * (MEMPOOL_F_CAPA_PHYS_CONTIG), or a maximum of the page size and total
> + * element size.
> + *
> + * Required memory chunk alignment is a maximum of page size and cache
> + * line size.
> + */
> +ssize_t rte_mempool_op_calc_mem_size_default(const struct rte_mempool *mp,
> +		uint32_t obj_num, uint32_t pg_shift,
> +		size_t *min_chunk_size, size_t *align);

For API docs and wording,

Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>

Should be pretty straightforward to rebase, so you probably should keep 
my ack for v4.

-- 
Thanks,
Anatoly