Function rte_mempool_populate_default

dpdk/lib/mempool/rte_mempool.c:483–622

Default function to populate the mempool: allocate memory in memzones, * and populate them. Return the number of objects added, or a negative * value on error. */

 * value on error.
 */
int
rte_mempool_populate_default(struct rte_mempool *mp)
{
	unsigned int mz_flags = RTE_MEMZONE_1GB|RTE_MEMZONE_SIZE_HINT_ONLY;
	char mz_name[RTE_MEMZONE_NAMESIZE];
	const struct rte_memzone *mz;
	ssize_t mem_size;
	size_t align, pg_sz, pg_shift = 0;
	rte_iova_t iova;
	unsigned mz_id, n;
	int ret;
	bool need_iova_contig_obj;
	size_t max_alloc_size = SIZE_MAX;

	ret = mempool_ops_alloc_once(mp);
	if (ret != 0)
		return ret;

	/* mempool must not be populated */
	if (mp->nb_mem_chunks != 0)
		return -EEXIST;

	/*
	 * the following section calculates page shift and page size values.
	 *
	 * these values impact the result of calc_mem_size operation, which
	 * returns the amount of memory that should be allocated to store the
	 * desired number of objects. when not zero, it allocates more memory
	 * for the padding between objects, to ensure that an object does not
	 * cross a page boundary. in other words, page size/shift are to be set
	 * to zero if mempool elements won't care about page boundaries.
	 * there are several considerations for page size and page shift here.
	 *
	 * if we don't need our mempools to have physically contiguous objects,
	 * then just set page shift and page size to 0, because the user has
	 * indicated that there's no need to care about anything.
	 *
	 * if we do need contiguous objects (if a mempool driver has its
	 * own calc_size() method returning min_chunk_size = mem_size),
	 * there is also an option to reserve the entire mempool memory
	 * as one contiguous block of memory.
	 *
	 * if we require contiguous objects, but not necessarily the entire
	 * mempool reserved space to be contiguous, pg_sz will be != 0,
	 * and the default ops->populate() will take care of not placing
	 * objects across pages.
	 *
	 * if our IO addresses are physical, we may get memory from bigger
	 * pages, or we might get memory from smaller pages, and how much of it
	 * we require depends on whether we want bigger or smaller pages.
	 * However, requesting each and every memory size is too much work, so
	 * what we'll do instead is walk through the page sizes available, pick
	 * the smallest one and set up page shift to match that one. We will be
	 * wasting some space this way, but it's much nicer than looping around
	 * trying to reserve each and every page size.
	 *
	 * If we fail to get enough contiguous memory, then we'll go and
	 * reserve space in smaller chunks.