[dpdk-dev] Question about cache_size in rte_mempool_create

[Roy Shterman]

Hi,

In the documentation it says that:

 * @param cache_size
 *   If cache_size is non-zero, the rte_mempool library will try to
 *   limit the accesses to the common lockless pool, by maintaining a
 *   per-lcore object cache. This argument must be lower or equal to
 *   CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE and n / 1.5.* It is advised to
choose*
* *   cache_size to have "n modulo cache_size == 0": if this is*
* *   not the case, some elements will always stay in the pool and will*
* *   never be used.* The access to the per-lcore table is of course
 *   faster than the multi-producer/consumer pool. The cache can be
 *   disabled if the cache_size argument is set to 0; it can be useful to
 *   avoid losing objects in cache.

I wonder if someone can please explain the high-lightened sentence, how the
cache size affects the objects inside the ring. And also does it mean that
if I'm sharing pool between different cores can it be that a core sees the
pool as empty although it has objects in it?

Thanks,
Roy