RE: [PATCH] mempool: simplify get objects

["Morten Brørup" <mb@smartsharesystems.com>]

PLEASE IGNORE.
The patch description is rubbish.
Will post a v2.

> From: Morten Brørup [mailto:mb@smartsharesystems.com]
> Sent: Tuesday, 20 January 2026 09.21
> 
> Removed explicit test for build time constant request size,
> and added comment that the compiler loop unrolls when request size is
> build time constant, to improve source code readability.
> 
> Also, when putting objects, the compiler does not know if calling
> rte_mempool_ops_enqueue_bulk() modifies cache->len, so load it before
> the
> call, so it doesn't have to be loaded again after the call.
> 
> Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
> ---
>  lib/mempool/rte_mempool.h | 38 ++++++++++----------------------------
>  1 file changed, 10 insertions(+), 28 deletions(-)
> 
> diff --git a/lib/mempool/rte_mempool.h b/lib/mempool/rte_mempool.h
> index aedc100964..61b415e336 100644
> --- a/lib/mempool/rte_mempool.h
> +++ b/lib/mempool/rte_mempool.h
> @@ -1410,8 +1410,9 @@ rte_mempool_do_generic_put(struct rte_mempool
> *mp, void * const *obj_table,
>  		 * Flush the cache to make room for the objects.
>  		 */
>  		cache_objs = &cache->objs[0];
> -		rte_mempool_ops_enqueue_bulk(mp, cache_objs, cache->len);
> +		const uint32_t len = cache->len;
>  		cache->len = n;
> +		rte_mempool_ops_enqueue_bulk(mp, cache_objs, len);
>  	} else {
>  		/* The request itself is too big for the cache. */
>  		goto driver_enqueue_stats_incremented;
> @@ -1531,11 +1532,11 @@ rte_mempool_do_generic_get(struct rte_mempool
> *mp, void **obj_table,
>  	cache_objs = &cache->objs[cache->len];
> 
>  	__rte_assume(cache->len <= RTE_MEMPOOL_CACHE_MAX_SIZE * 2);
> -	if (__rte_constant(n) && n <= cache->len) {
> +	if (likely(n <= cache->len)) {
>  		/*
> -		 * The request size is known at build time, and
> -		 * the entire request can be satisfied from the cache,
> -		 * so let the compiler unroll the fixed length copy loop.
> +		 * The entire request can be satisfied from the cache.
> +		 * If the request size is known at build time,
> +		 * the compiler unrolls the fixed length copy loop.
>  		 */
>  		cache->len -= n;
>  		for (index = 0; index < n; index++)
> @@ -1547,31 +1548,13 @@ rte_mempool_do_generic_get(struct rte_mempool
> *mp, void **obj_table,
>  		return 0;
>  	}
> 
> -	/*
> -	 * Use the cache as much as we have to return hot objects first.
> -	 * If the request size 'n' is known at build time, the above
> comparison
> -	 * ensures that n > cache->len here, so omit RTE_MIN().
> -	 */
> -	len = __rte_constant(n) ? cache->len : RTE_MIN(n, cache->len);
> -	cache->len -= len;
> +	/* Use the cache as much as we have to return hot objects first.
> */
> +	len = cache->len;
>  	remaining = n - len;
> +	cache->len = 0;
>  	for (index = 0; index < len; index++)
>  		*obj_table++ = *--cache_objs;
> 
> -	/*
> -	 * If the request size 'n' is known at build time, the case
> -	 * where the entire request can be satisfied from the cache
> -	 * has already been handled above, so omit handling it here.
> -	 */
> -	if (!__rte_constant(n) && likely(remaining == 0)) {
> -		/* The entire request is satisfied from the cache. */
> -
> -		RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_bulk, 1);
> -		RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_objs, n);
> -
> -		return 0;
> -	}
> -
>  	/* Dequeue below would overflow mem allocated for cache? */
>  	if (unlikely(remaining > RTE_MEMPOOL_CACHE_MAX_SIZE))
>  		goto driver_dequeue;
> @@ -1592,11 +1575,10 @@ rte_mempool_do_generic_get(struct rte_mempool
> *mp, void **obj_table,
>  	__rte_assume(cache->size <= RTE_MEMPOOL_CACHE_MAX_SIZE);
>  	__rte_assume(remaining <= RTE_MEMPOOL_CACHE_MAX_SIZE);
>  	cache_objs = &cache->objs[cache->size + remaining];
> +	cache->len = cache->size;
>  	for (index = 0; index < remaining; index++)
>  		*obj_table++ = *--cache_objs;
> 
> -	cache->len = cache->size;
> -
>  	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_bulk, 1);
>  	RTE_MEMPOOL_CACHE_STAT_ADD(cache, get_success_objs, n);
> 
> --
> 2.43.0