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To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, dev@dpdk.org
References: <1464101442-10501-1-git-send-email-jerin.jacob@caviumnetworks.com>
 <1464250025-9191-1-git-send-email-jerin.jacob@caviumnetworks.com>
Cc: thomas.monjalon@6wind.com, bruce.richardson@intel.com,
 konstantin.ananyev@intel.com
From: Olivier Matz <olivier.matz@6wind.com>
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Date: Mon, 30 May 2016 10:45:11 +0200
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Subject: Re: [dpdk-dev] [PATCH v2] mempool: replace c memcpy code semantics
 with optimized rte_memcpy
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Hi Jerin,

On 05/26/2016 10:07 AM, Jerin Jacob wrote:
> Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> ---
> v1..v2
> Corrected the the git commit message(s/mbuf/mempool/g)
> ---
>  lib/librte_mempool/rte_mempool.h | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> index 60339bd..24876a2 100644
> --- a/lib/librte_mempool/rte_mempool.h
> +++ b/lib/librte_mempool/rte_mempool.h
> @@ -73,6 +73,7 @@
>  #include <rte_memory.h>
>  #include <rte_branch_prediction.h>
>  #include <rte_ring.h>
> +#include <rte_memcpy.h>
>  
>  #ifdef __cplusplus
>  extern "C" {
> @@ -739,7 +740,6 @@ __mempool_put_bulk(struct rte_mempool *mp, void * const *obj_table,
>  		    unsigned n, int is_mp)
>  {
>  	struct rte_mempool_cache *cache;
> -	uint32_t index;
>  	void **cache_objs;
>  	unsigned lcore_id = rte_lcore_id();
>  	uint32_t cache_size = mp->cache_size;
> @@ -768,8 +768,7 @@ __mempool_put_bulk(struct rte_mempool *mp, void * const *obj_table,
>  	 */
>  
>  	/* Add elements back into the cache */
> -	for (index = 0; index < n; ++index, obj_table++)
> -		cache_objs[index] = *obj_table;
> +	rte_memcpy(&cache_objs[0], obj_table, sizeof(void *) * n);
>  
>  	cache->len += n;
>  
> 

I also checked in the get_bulk() function, which looks like that:

	/* Now fill in the response ... */
	for (index = 0, len = cache->len - 1;
			index < n;
			++index, len--, obj_table++)
		*obj_table = cache_objs[len];

I think we could replace it by something like:

	rte_memcpy(obj_table, &cache_objs[len - n], sizeof(void *) * n);

The only difference is that it won't reverse the pointers in the
table, but I don't see any problem with that.

What do you think?


Regards,
Olivier