[dpdk-dev] [PATCH v6 7/8] mempool: introduce block size align flag

[Hemant Agrawal]

Tested-by:  Hemant Agrawal <hemant.agrawal at nxp.com>

On 9/7/2017 9:00 PM, Santosh Shukla wrote:
> Some mempool hw like octeontx/fpa block, demands block size
> (/total_elem_sz) aligned object start address.
>
> Introducing an MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS flag.
> If this flag is set:
> - Align object start address(vaddr) to a multiple of total_elt_sz.
> - Allocate one additional object. Additional object is needed to make
>   sure that requested 'n' object gets correctly populated.
>
> Example:
> - Let's say that we get 'x' size of memory chunk from memzone.
> - And application has requested 'n' object from mempool.
> - Ideally, we start using objects at start address 0 to...(x-block_sz)
>   for n obj.
> - Not necessarily first object address i.e. 0 is aligned to block_sz.
> - So we derive 'offset' value for block_sz alignment purpose i.e..'off'.
> - That 'off' makes sure that start address of object is blk_sz aligned.
> - Calculating 'off' may end up sacrificing first block_sz area of
>   memzone area x. So total number of the object which can fit in the
>   pool area is n-1, Which is incorrect behavior.
>
> Therefore we request one additional object (/block_sz area) from memzone
> when MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS flag is set.
>
> Signed-off-by: Santosh Shukla <santosh.shukla at caviumnetworks.com>
> Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
> ---
> v5 --> v6:
> - Renamed from MEMPOOL_F_BLK_ALIGNED_OBJECTS to
>   MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS. (Suggested by Olivier)
> - Updated Capability flag descrioption (Suggested by Olivier)
>
> History refer [1]
> [1] http://dpdk.org/dev/patchwork/patch/28418/
>
> v4 --> v5:
> - Added vaddr in git description of patch (suggested by Olivier)
> - Renamed to aligned flag to MEMPOOL_F_BLK_ALIGNED_OBJECTS (suggested by
>   Olivier)
> Refer [2].
> [2] http://dpdk.org/dev/patchwork/patch/27600/
>
>  lib/librte_mempool/rte_mempool.c | 19 ++++++++++++++++---
>  lib/librte_mempool/rte_mempool.h | 12 ++++++++++++
>  2 files changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 146e38675..decdda3a6 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -239,10 +239,15 @@ rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags,
>   */
>  size_t
>  rte_mempool_xmem_size(uint32_t elt_num, size_t total_elt_sz, uint32_t pg_shift,
> -		      __rte_unused unsigned int flags)
> +		      unsigned int flags)
>  {
>  	size_t obj_per_page, pg_num, pg_sz;
>
> +	if (flags & (MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS |
> +			MEMPOOL_F_CAPA_PHYS_CONTIG))
> +		/* alignment need one additional object */
> +		elt_num += 1;
> +
>  	if (total_elt_sz == 0)
>  		return 0;
>
> @@ -265,13 +270,18 @@ rte_mempool_xmem_size(uint32_t elt_num, size_t total_elt_sz, uint32_t pg_shift,
>  ssize_t
>  rte_mempool_xmem_usage(__rte_unused void *vaddr, uint32_t elt_num,
>  	size_t total_elt_sz, const phys_addr_t paddr[], uint32_t pg_num,
> -	uint32_t pg_shift, __rte_unused unsigned int flags)
> +	uint32_t pg_shift, unsigned int flags)
>  {
>  	uint32_t elt_cnt = 0;
>  	phys_addr_t start, end;
>  	uint32_t paddr_idx;
>  	size_t pg_sz = (size_t)1 << pg_shift;
>
> +	if (flags & (MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS |
> +			MEMPOOL_F_CAPA_PHYS_CONTIG))
> +		/* alignment need one additional object */
> +		elt_num += 1;
> +
>  	/* if paddr is NULL, assume contiguous memory */
>  	if (paddr == NULL) {
>  		start = 0;
> @@ -390,7 +400,10 @@ rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
>  	memhdr->free_cb = free_cb;
>  	memhdr->opaque = opaque;
>
> -	if (mp->flags & MEMPOOL_F_NO_CACHE_ALIGN)
> +	if (mp->flags & MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS)
> +		/* align object start address to a multiple of total_elt_sz */
> +		off = total_elt_sz - ((uintptr_t)vaddr % total_elt_sz);
> +	else if (mp->flags & MEMPOOL_F_NO_CACHE_ALIGN)
>  		off = RTE_PTR_ALIGN_CEIL(vaddr, 8) - vaddr;
>  	else
>  		off = RTE_PTR_ALIGN_CEIL(vaddr, RTE_CACHE_LINE_SIZE) - vaddr;
> diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> index 734392556..24195dda0 100644
> --- a/lib/librte_mempool/rte_mempool.h
> +++ b/lib/librte_mempool/rte_mempool.h
> @@ -271,6 +271,18 @@ struct rte_mempool {
>   * Note: This flag should not be passed by application.
>   */
>  #define MEMPOOL_F_CAPA_PHYS_CONTIG 0x0040
> +/**
> + * This capability flag is advertised by a mempool handler. Used for a case
> + * where mempool driver wants object start address(vaddr) aligned to block
> + * size(/ total element size).
> + *
> + * Note:
> + * - This flag should not be passed by application.
> + *   Flag used for mempool driver only.
> + * - Mempool driver must also set MEMPOOL_F_CAPA_PHYS_CONTIG flag along with
> + *   MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS.
> + */
> +#define MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS 0x0080
>
>  /**
>   * @internal When debug is enabled, store some statistics.
>