Re: [dpdk-dev] [PATCHv2] mempool: fix pages computation to determine number of objects

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

On Wed, May 27, 2015 at 01:41:09AM +0100, Konstantin Ananyev wrote:
> v2:
> - As suggested in comments use slightly different approach for the fix.
> 
> In rte_mempool_obj_iter(), when element boundary coincides with page boundary,
> even if a single page is required per object, a loop checks that the next page
> is contiguous and drops the first oneo therwise.
> 
> This commit checks subsequent pages only when several are required per object.
> 
> Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

Tested and validated patch which supersedes my previous attempt in the other
thread. There's only a typo in the commit log ("oneo therwise").

Reviewed-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

> ---
>  lib/librte_mempool/rte_mempool.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index 01972ba..ecb03b3 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -156,7 +156,7 @@ rte_mempool_obj_iter(void *vaddr, uint32_t elt_num, size_t elt_sz, size_t align,
>  	rte_mempool_obj_iter_t obj_iter, void *obj_iter_arg)
>  {
>  	uint32_t i, j, k;
> -	uint32_t pgn;
> +	uint32_t pgn, pgf;
>  	uintptr_t end, start, va;
>  	uintptr_t pg_sz;
>  
> @@ -171,10 +171,14 @@ rte_mempool_obj_iter(void *vaddr, uint32_t elt_num, size_t elt_sz, size_t align,
>  		start = RTE_ALIGN_CEIL(va, align);
>  		end = start + elt_sz;
>  
> -		pgn = (end >> pg_shift) - (start >> pg_shift);
> +		/* index of the first page for the next element. */
> +		pgf = (end >> pg_shift) - (start >> pg_shift);
> +
> +		/* index of the last page for the current element. */
> +		pgn = ((end - 1) >> pg_shift) - (start >> pg_shift);
>  		pgn += j;
>  
> -		/* do we have enough space left for the next element. */
> +		/* do we have enough space left for the element. */
>  		if (pgn >= pg_num)
>  			break;
>  
> @@ -194,7 +198,7 @@ rte_mempool_obj_iter(void *vaddr, uint32_t elt_num, size_t elt_sz, size_t align,
>  				obj_iter(obj_iter_arg, (void *)start,
>  					(void *)end, i);
>  			va = end;
> -			j = pgn;
> +			j += pgf;
>  			i++;
>  		} else {
>  			va = RTE_ALIGN_CEIL((va + 1), pg_sz);
> -- 
> 1.8.5.3
> 

-- 
Adrien Mazarguil
6WIND