mempool: fix trailer address

[dpdk.git] / lib / librte_mempool / rte_mempool.h

/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
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#ifndef _RTE_MEMPOOL_H_
#define _RTE_MEMPOOL_H_

/**
 * @file
 * RTE Mempool.
 *
 * A memory pool is an allocator of fixed-size object. It is
 * identified by its name, and uses a ring to store free objects. It
 * provides some other optional services, like a per-core object
 * cache, and an alignment helper to ensure that objects are padded
 * to spread them equally on all RAM channels, ranks, and so on.
 *
 * Objects owned by a mempool should never be added in another
 * mempool. When an object is freed using rte_mempool_put() or
 * equivalent, the object data is not modified; the user can save some
 * meta-data in the object data and retrieve them when allocating a
 * new object.
 *
 * Note: the mempool implementation is not preemptable. A lcore must
 * not be interrupted by another task that uses the same mempool
 * (because it uses a ring which is not preemptable). Also, mempool
 * functions must not be used outside the DPDK environment: for
 * example, in linuxapp environment, a thread that is not created by
 * the EAL must not use mempools. This is due to the per-lcore cache
 * that won't work as rte_lcore_id() will not return a correct value.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <inttypes.h>
#include <sys/queue.h>

#include <rte_log.h>
#include <rte_debug.h>
#include <rte_lcore.h>
#include <rte_memory.h>
#include <rte_branch_prediction.h>
#include <rte_ring.h>

#ifdef __cplusplus
extern "C" {
#endif

#define RTE_MEMPOOL_HEADER_COOKIE1  0xbadbadbadadd2e55ULL /**< Header cookie. */
#define RTE_MEMPOOL_HEADER_COOKIE2  0xf2eef2eedadd2e55ULL /**< Header cookie. */
#define RTE_MEMPOOL_TRAILER_COOKIE  0xadd2e55badbadbadULL /**< Trailer cookie.*/

#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
/**
 * A structure that stores the mempool statistics (per-lcore).
 */
struct rte_mempool_debug_stats {
        uint64_t put_bulk;         /**< Number of puts. */
        uint64_t put_objs;         /**< Number of objects successfully put. */
        uint64_t get_success_bulk; /**< Successful allocation number. */
        uint64_t get_success_objs; /**< Objects successfully allocated. */
        uint64_t get_fail_bulk;    /**< Failed allocation number. */
        uint64_t get_fail_objs;    /**< Objects that failed to be allocated. */
} __rte_cache_aligned;
#endif

#if RTE_MEMPOOL_CACHE_MAX_SIZE > 0
/**
 * A structure that stores a per-core object cache.
 */
struct rte_mempool_cache {
        unsigned len; /**< Cache len */
        /*
         * Cache is allocated to this size to allow it to overflow in certain
         * cases to avoid needless emptying of cache.
         */
        void *objs[RTE_MEMPOOL_CACHE_MAX_SIZE * 3]; /**< Cache objects */
} __rte_cache_aligned;
#endif /* RTE_MEMPOOL_CACHE_MAX_SIZE > 0 */

/**
 * A structure that stores the size of mempool elements.
 */
struct rte_mempool_objsz {
        uint32_t elt_size;     /**< Size of an element. */
        uint32_t header_size;  /**< Size of header (before elt). */
        uint32_t trailer_size; /**< Size of trailer (after elt). */
        uint32_t total_size;
        /**< Total size of an object (header + elt + trailer). */
};

#define RTE_MEMPOOL_NAMESIZE 32 /**< Maximum length of a memory pool. */
#define RTE_MEMPOOL_MZ_PREFIX "MP_"

/* "MP_<name>" */
#define RTE_MEMPOOL_MZ_FORMAT   RTE_MEMPOOL_MZ_PREFIX "%s"

#ifdef RTE_LIBRTE_XEN_DOM0

/* "<name>_MP_elt" */
#define RTE_MEMPOOL_OBJ_NAME    "%s_" RTE_MEMPOOL_MZ_PREFIX "elt"

#else

#define RTE_MEMPOOL_OBJ_NAME    RTE_MEMPOOL_MZ_FORMAT

#endif /* RTE_LIBRTE_XEN_DOM0 */

#define MEMPOOL_PG_SHIFT_MAX    (sizeof(uintptr_t) * CHAR_BIT - 1)

/** Mempool over one chunk of physically continuous memory */
#define MEMPOOL_PG_NUM_DEFAULT  1

#ifndef RTE_MEMPOOL_ALIGN
#define RTE_MEMPOOL_ALIGN       RTE_CACHE_LINE_SIZE
#endif

#define RTE_MEMPOOL_ALIGN_MASK  (RTE_MEMPOOL_ALIGN - 1)

/**
 * Mempool object header structure
 *
 * Each object stored in mempools are prefixed by this header structure,
 * it allows to retrieve the mempool pointer from the object. When debug
 * is enabled, a cookie is also added in this structure preventing
 * corruptions and double-frees.
 */
struct rte_mempool_objhdr {
        struct rte_mempool *mp;          /**< The mempool owning the object. */
#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
        uint64_t cookie;                 /**< Debug cookie. */
#endif
};

/**
 * Mempool object trailer structure
 *
 * In debug mode, each object stored in mempools are suffixed by this
 * trailer structure containing a cookie preventing memory corruptions.
 */
struct rte_mempool_objtlr {
#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
        uint64_t cookie;                 /**< Debug cookie. */
#endif
};

/**
 * The RTE mempool structure.
 */
struct rte_mempool {
        char name[RTE_MEMPOOL_NAMESIZE]; /**< Name of mempool. */
        struct rte_ring *ring;           /**< Ring to store objects. */
        phys_addr_t phys_addr;           /**< Phys. addr. of mempool struct. */
        int flags;                       /**< Flags of the mempool. */
        uint32_t size;                   /**< Size of the mempool. */
        uint32_t cache_size;             /**< Size of per-lcore local cache. */
        uint32_t cache_flushthresh;
        /**< Threshold before we flush excess elements. */

        uint32_t elt_size;               /**< Size of an element. */
        uint32_t header_size;            /**< Size of header (before elt). */
        uint32_t trailer_size;           /**< Size of trailer (after elt). */

        unsigned private_data_size;      /**< Size of private data. */

#if RTE_MEMPOOL_CACHE_MAX_SIZE > 0
        /** Per-lcore local cache. */
        struct rte_mempool_cache local_cache[RTE_MAX_LCORE];
#endif

#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
        /** Per-lcore statistics. */
        struct rte_mempool_debug_stats stats[RTE_MAX_LCORE];
#endif

        /* Address translation support, starts from next cache line. */

        /** Number of elements in the elt_pa array. */
        uint32_t    pg_num __rte_cache_aligned;
        uint32_t    pg_shift;     /**< LOG2 of the physical pages. */
        uintptr_t   pg_mask;      /**< physical page mask value. */
        uintptr_t   elt_va_start;
        /**< Virtual address of the first mempool object. */
        uintptr_t   elt_va_end;
        /**< Virtual address of the <size + 1> mempool object. */
        phys_addr_t elt_pa[MEMPOOL_PG_NUM_DEFAULT];
        /**< Array of physical page addresses for the mempool objects buffer. */

}  __rte_cache_aligned;

#define MEMPOOL_F_NO_SPREAD      0x0001 /**< Do not spread in memory. */
#define MEMPOOL_F_NO_CACHE_ALIGN 0x0002 /**< Do not align objs on cache lines.*/
#define MEMPOOL_F_SP_PUT         0x0004 /**< Default put is "single-producer".*/
#define MEMPOOL_F_SC_GET         0x0008 /**< Default get is "single-consumer".*/

/**
 * @internal When debug is enabled, store some statistics.
 *
 * @param mp
 *   Pointer to the memory pool.
 * @param name
 *   Name of the statistics field to increment in the memory pool.
 * @param n
 *   Number to add to the object-oriented statistics.
 */
#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
#define __MEMPOOL_STAT_ADD(mp, name, n) do {                    \
                unsigned __lcore_id = rte_lcore_id();           \
                if (__lcore_id < RTE_MAX_LCORE) {               \
                        mp->stats[__lcore_id].name##_objs += n; \
                        mp->stats[__lcore_id].name##_bulk += 1; \
                }                                               \
        } while(0)
#else
#define __MEMPOOL_STAT_ADD(mp, name, n) do {} while(0)
#endif

/**
 * Calculate the size of the mempool header.
 *
 * @param mp
 *   Pointer to the memory pool.
 * @param pgn
 *   Number of pages used to store mempool objects.
 */
#define MEMPOOL_HEADER_SIZE(mp, pgn)    (sizeof(*(mp)) + \
        RTE_ALIGN_CEIL(((pgn) - RTE_DIM((mp)->elt_pa)) * \
        sizeof ((mp)->elt_pa[0]), RTE_CACHE_LINE_SIZE))

/**
 * Return true if the whole mempool is in contiguous memory.
 */
#define MEMPOOL_IS_CONTIG(mp)                      \
        ((mp)->pg_num == MEMPOOL_PG_NUM_DEFAULT && \
        (mp)->phys_addr == (mp)->elt_pa[0])

/* return the header of a mempool object (internal) */
static inline struct rte_mempool_objhdr *__mempool_get_header(void *obj)
{
        return RTE_PTR_SUB(obj, sizeof(struct rte_mempool_objhdr));
}

/**
 * Return a pointer to the mempool owning this object.
 *
 * @param obj
 *   An object that is owned by a pool. If this is not the case,
 *   the behavior is undefined.
 * @return
 *   A pointer to the mempool structure.
 */
static inline struct rte_mempool *rte_mempool_from_obj(void *obj)
{
        struct rte_mempool_objhdr *hdr = __mempool_get_header(obj);
        return hdr->mp;
}

/* return the trailer of a mempool object (internal) */
static inline struct rte_mempool_objtlr *__mempool_get_trailer(void *obj)
{
        struct rte_mempool *mp = rte_mempool_from_obj(obj);
        return RTE_PTR_ADD(obj, mp->elt_size);
}

/**
 * @internal Check and update cookies or panic.
 *
 * @param mp
 *   Pointer to the memory pool.
 * @param obj_table_const
 *   Pointer to a table of void * pointers (objects).
 * @param n
 *   Index of object in object table.
 * @param free
 *   - 0: object is supposed to be allocated, mark it as free
 *   - 1: object is supposed to be free, mark it as allocated
 *   - 2: just check that cookie is valid (free or allocated)
 */
#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
#ifndef __INTEL_COMPILER
#pragma GCC diagnostic ignored "-Wcast-qual"
#endif
static inline void __mempool_check_cookies(const struct rte_mempool *mp,
                                           void * const *obj_table_const,
                                           unsigned n, int free)
{
        struct rte_mempool_objhdr *hdr;
        struct rte_mempool_objtlr *tlr;
        uint64_t cookie;
        void *tmp;
        void *obj;
        void **obj_table;

        /* Force to drop the "const" attribute. This is done only when
         * DEBUG is enabled */
        tmp = (void *) obj_table_const;
        obj_table = (void **) tmp;

        while (n--) {
                obj = obj_table[n];

                if (rte_mempool_from_obj(obj) != mp)
                        rte_panic("MEMPOOL: object is owned by another "
                                  "mempool\n");

                hdr = __mempool_get_header(obj);
                cookie = hdr->cookie;

                if (free == 0) {
                        if (cookie != RTE_MEMPOOL_HEADER_COOKIE1) {
                                rte_log_set_history(0);
                                RTE_LOG(CRIT, MEMPOOL,
                                        "obj=%p, mempool=%p, cookie=%" PRIx64 "\n",
                                        obj, (const void *) mp, cookie);
                                rte_panic("MEMPOOL: bad header cookie (put)\n");
                        }
                        hdr->cookie = RTE_MEMPOOL_HEADER_COOKIE2;
                }
                else if (free == 1) {
                        if (cookie != RTE_MEMPOOL_HEADER_COOKIE2) {
                                rte_log_set_history(0);
                                RTE_LOG(CRIT, MEMPOOL,
                                        "obj=%p, mempool=%p, cookie=%" PRIx64 "\n",
                                        obj, (const void *) mp, cookie);
                                rte_panic("MEMPOOL: bad header cookie (get)\n");
                        }
                        hdr->cookie = RTE_MEMPOOL_HEADER_COOKIE1;
                }
                else if (free == 2) {
                        if (cookie != RTE_MEMPOOL_HEADER_COOKIE1 &&
                            cookie != RTE_MEMPOOL_HEADER_COOKIE2) {
                                rte_log_set_history(0);
                                RTE_LOG(CRIT, MEMPOOL,
                                        "obj=%p, mempool=%p, cookie=%" PRIx64 "\n",
                                        obj, (const void *) mp, cookie);
                                rte_panic("MEMPOOL: bad header cookie (audit)\n");
                        }
                }
                tlr = __mempool_get_trailer(obj);
                cookie = tlr->cookie;
                if (cookie != RTE_MEMPOOL_TRAILER_COOKIE) {
                        rte_log_set_history(0);
                        RTE_LOG(CRIT, MEMPOOL,
                                "obj=%p, mempool=%p, cookie=%" PRIx64 "\n",
                                obj, (const void *) mp, cookie);
                        rte_panic("MEMPOOL: bad trailer cookie\n");
                }
        }
}
#ifndef __INTEL_COMPILER
#pragma GCC diagnostic error "-Wcast-qual"
#endif
#else
#define __mempool_check_cookies(mp, obj_table_const, n, free) do {} while(0)
#endif /* RTE_LIBRTE_MEMPOOL_DEBUG */

/**
 * A mempool object iterator callback function.
 */
typedef void (*rte_mempool_obj_iter_t)(void * /*obj_iter_arg*/,
        void * /*obj_start*/,
        void * /*obj_end*/,
        uint32_t /*obj_index */);

/**
 * Call a function for each mempool object in a memory chunk
 *
 * Iterate across objects of the given size and alignment in the
 * provided chunk of memory. The given memory buffer can consist of
 * disjointed physical pages.
 *
 * For each object, call the provided callback (if any). This function
 * is used to populate a mempool, or walk through all the elements of a
 * mempool, or estimate how many elements of the given size could be
 * created in the given memory buffer.
 *
 * @param vaddr
 *   Virtual address of the memory buffer.
 * @param elt_num
 *   Maximum number of objects to iterate through.
 * @param elt_sz
 *   Size of each object.
 * @param align
 *   Alignment of each object.
 * @param paddr
 *   Array of physical addresses of the pages that comprises given memory
 *   buffer.
 * @param pg_num
 *   Number of elements in the paddr array.
 * @param pg_shift
 *   LOG2 of the physical pages size.
 * @param obj_iter
 *   Object iterator callback function (could be NULL).
 * @param obj_iter_arg
 *   User defined parameter for the object iterator callback function.
 *
 * @return
 *   Number of objects iterated through.
 */
uint32_t rte_mempool_obj_iter(void *vaddr,
        uint32_t elt_num, size_t elt_sz, size_t align,
        const phys_addr_t paddr[], uint32_t pg_num, uint32_t pg_shift,
        rte_mempool_obj_iter_t obj_iter, void *obj_iter_arg);

/**
 * An object constructor callback function for mempool.
 *
 * Arguments are the mempool, the opaque pointer given by the user in
 * rte_mempool_create(), the pointer to the element and the index of
 * the element in the pool.
 */
typedef void (rte_mempool_obj_ctor_t)(struct rte_mempool *, void *,
                                      void *, unsigned);

/**
 * A mempool constructor callback function.
 *
 * Arguments are the mempool and the opaque pointer given by the user in
 * rte_mempool_create().
 */
typedef void (rte_mempool_ctor_t)(struct rte_mempool *, void *);

/**
 * Create a new mempool named *name* in memory.
 *
 * This function uses ``memzone_reserve()`` to allocate memory. The
 * pool contains n elements of elt_size. Its size is set to n.
 * All elements of the mempool are allocated together with the mempool header,
 * in one physically continuous chunk of memory.
 *
 * @param name
 *   The name of the mempool.
 * @param n
 *   The number of elements in the mempool. The optimum size (in terms of
 *   memory usage) for a mempool is when n is a power of two minus one:
 *   n = (2^q - 1).
 * @param elt_size
 *   The size of each element.
 * @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. Note that even if not used, the
 *   memory space for cache is always reserved in a mempool structure,
 *   except if CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE is set to 0.
 * @param private_data_size
 *   The size of the private data appended after the mempool
 *   structure. This is useful for storing some private data after the
 *   mempool structure, as is done for rte_mbuf_pool for example.
 * @param mp_init
 *   A function pointer that is called for initialization of the pool,
 *   before object initialization. The user can initialize the private
 *   data in this function if needed. This parameter can be NULL if
 *   not needed.
 * @param mp_init_arg
 *   An opaque pointer to data that can be used in the mempool
 *   constructor function.
 * @param obj_init
 *   A function pointer that is called for each object at
 *   initialization of the pool. The user can set some meta data in
 *   objects if needed. This parameter can be NULL if not needed.
 *   The obj_init() function takes the mempool pointer, the init_arg,
 *   the object pointer and the object number as parameters.
 * @param obj_init_arg
 *   An opaque pointer to data that can be used as an argument for
 *   each call to the object constructor function.
 * @param socket_id
 *   The *socket_id* argument is the socket identifier in the case of
 *   NUMA. The value can be *SOCKET_ID_ANY* if there is no NUMA
 *   constraint for the reserved zone.
 * @param flags
 *   The *flags* arguments is an OR of following flags:
 *   - MEMPOOL_F_NO_SPREAD: By default, objects addresses are spread
 *     between channels in RAM: the pool allocator will add padding
 *     between objects depending on the hardware configuration. See
 *     Memory alignment constraints for details. If this flag is set,
 *     the allocator will just align them to a cache line.
 *   - MEMPOOL_F_NO_CACHE_ALIGN: By default, the returned objects are
 *     cache-aligned. This flag removes this constraint, and no
 *     padding will be present between objects. This flag implies
 *     MEMPOOL_F_NO_SPREAD.
 *   - MEMPOOL_F_SP_PUT: If this flag is set, the default behavior
 *     when using rte_mempool_put() or rte_mempool_put_bulk() is
 *     "single-producer". Otherwise, it is "multi-producers".
 *   - MEMPOOL_F_SC_GET: If this flag is set, the default behavior
 *     when using rte_mempool_get() or rte_mempool_get_bulk() is
 *     "single-consumer". Otherwise, it is "multi-consumers".
 * @return
 *   The pointer to the new allocated mempool, on success. NULL on error
 *   with rte_errno set appropriately. Possible rte_errno values include:
 *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 *    - E_RTE_SECONDARY - function was called from a secondary process instance
 *    - EINVAL - cache size provided is too large
 *    - ENOSPC - the maximum number of memzones has already been allocated
 *    - EEXIST - a memzone with the same name already exists
 *    - ENOMEM - no appropriate memory area found in which to create memzone
 */
struct rte_mempool *
rte_mempool_create(const char *name, unsigned n, unsigned elt_size,
                   unsigned cache_size, unsigned private_data_size,
                   rte_mempool_ctor_t *mp_init, void *mp_init_arg,
                   rte_mempool_obj_ctor_t *obj_init, void *obj_init_arg,
                   int socket_id, unsigned flags);

/**
 * Create a new mempool named *name* in memory.
 *
 * This function uses ``memzone_reserve()`` to allocate memory. The
 * pool contains n elements of elt_size. Its size is set to n.
 * Depending on the input parameters, mempool elements can be either allocated
 * together with the mempool header, or an externally provided memory buffer
 * could be used to store mempool objects. In later case, that external
 * memory buffer can consist of set of disjoint physical pages.
 *
 * @param name
 *   The name of the mempool.
 * @param n
 *   The number of elements in the mempool. The optimum size (in terms of
 *   memory usage) for a mempool is when n is a power of two minus one:
 *   n = (2^q - 1).
 * @param elt_size
 *   The size of each element.
 * @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. 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. Note that even if not used, the
 *   memory space for cache is always reserved in a mempool structure,
 *   except if CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE is set to 0.
 * @param private_data_size
 *   The size of the private data appended after the mempool
 *   structure. This is useful for storing some private data after the
 *   mempool structure, as is done for rte_mbuf_pool for example.
 * @param mp_init
 *   A function pointer that is called for initialization of the pool,
 *   before object initialization. The user can initialize the private
 *   data in this function if needed. This parameter can be NULL if
 *   not needed.
 * @param mp_init_arg
 *   An opaque pointer to data that can be used in the mempool
 *   constructor function.
 * @param obj_init
 *   A function pointer that is called for each object at
 *   initialization of the pool. The user can set some meta data in
 *   objects if needed. This parameter can be NULL if not needed.
 *   The obj_init() function takes the mempool pointer, the init_arg,
 *   the object pointer and the object number as parameters.
 * @param obj_init_arg
 *   An opaque pointer to data that can be used as an argument for
 *   each call to the object constructor function.
 * @param socket_id
 *   The *socket_id* argument is the socket identifier in the case of
 *   NUMA. The value can be *SOCKET_ID_ANY* if there is no NUMA
 *   constraint for the reserved zone.
 * @param flags
 *   The *flags* arguments is an OR of following flags:
 *   - MEMPOOL_F_NO_SPREAD: By default, objects addresses are spread
 *     between channels in RAM: the pool allocator will add padding
 *     between objects depending on the hardware configuration. See
 *     Memory alignment constraints for details. If this flag is set,
 *     the allocator will just align them to a cache line.
 *   - MEMPOOL_F_NO_CACHE_ALIGN: By default, the returned objects are
 *     cache-aligned. This flag removes this constraint, and no
 *     padding will be present between objects. This flag implies
 *     MEMPOOL_F_NO_SPREAD.
 *   - MEMPOOL_F_SP_PUT: If this flag is set, the default behavior
 *     when using rte_mempool_put() or rte_mempool_put_bulk() is
 *     "single-producer". Otherwise, it is "multi-producers".
 *   - MEMPOOL_F_SC_GET: If this flag is set, the default behavior
 *     when using rte_mempool_get() or rte_mempool_get_bulk() is
 *     "single-consumer". Otherwise, it is "multi-consumers".
 * @param vaddr
 *   Virtual address of the externally allocated memory buffer.
 *   Will be used to store mempool objects.
 * @param paddr
 *   Array of physical addresses of the pages that comprises given memory
 *   buffer.
 * @param pg_num
 *   Number of elements in the paddr array.
 * @param pg_shift
 *   LOG2 of the physical pages size.
 * @return
 *   The pointer to the new allocated mempool, on success. NULL on error
 *   with rte_errno set appropriately. Possible rte_errno values include:
 *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 *    - E_RTE_SECONDARY - function was called from a secondary process instance
 *    - EINVAL - cache size provided is too large
 *    - ENOSPC - the maximum number of memzones has already been allocated
 *    - EEXIST - a memzone with the same name already exists
 *    - ENOMEM - no appropriate memory area found in which to create memzone
 */
struct rte_mempool *
rte_mempool_xmem_create(const char *name, unsigned n, unsigned elt_size,
                unsigned cache_size, unsigned private_data_size,
                rte_mempool_ctor_t *mp_init, void *mp_init_arg,
                rte_mempool_obj_ctor_t *obj_init, void *obj_init_arg,
                int socket_id, unsigned flags, void *vaddr,
                const phys_addr_t paddr[], uint32_t pg_num, uint32_t pg_shift);

#ifdef RTE_LIBRTE_XEN_DOM0
/**
 * Create a new mempool named *name* in memory on Xen Dom0.
 *
 * This function uses ``rte_mempool_xmem_create()`` to allocate memory. The
 * pool contains n elements of elt_size. Its size is set to n.
 * All elements of the mempool are allocated together with the mempool header,
 * and memory buffer can consist of set of disjoint physical pages.
 *
 * @param name
 *   The name of the mempool.
 * @param n
 *   The number of elements in the mempool. The optimum size (in terms of
 *   memory usage) for a mempool is when n is a power of two minus one:
 *   n = (2^q - 1).
 * @param elt_size
 *   The size of each element.
 * @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. 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. Note that even if not used, the
 *   memory space for cache is always reserved in a mempool structure,
 *   except if CONFIG_RTE_MEMPOOL_CACHE_MAX_SIZE is set to 0.
 * @param private_data_size
 *   The size of the private data appended after the mempool
 *   structure. This is useful for storing some private data after the
 *   mempool structure, as is done for rte_mbuf_pool for example.
 * @param mp_init
 *   A function pointer that is called for initialization of the pool,
 *   before object initialization. The user can initialize the private
 *   data in this function if needed. This parameter can be NULL if
 *   not needed.
 * @param mp_init_arg
 *   An opaque pointer to data that can be used in the mempool
 *   constructor function.
 * @param obj_init
 *   A function pointer that is called for each object at
 *   initialization of the pool. The user can set some meta data in
 *   objects if needed. This parameter can be NULL if not needed.
 *   The obj_init() function takes the mempool pointer, the init_arg,
 *   the object pointer and the object number as parameters.
 * @param obj_init_arg
 *   An opaque pointer to data that can be used as an argument for
 *   each call to the object constructor function.
 * @param socket_id
 *   The *socket_id* argument is the socket identifier in the case of
 *   NUMA. The value can be *SOCKET_ID_ANY* if there is no NUMA
 *   constraint for the reserved zone.
 * @param flags
 *   The *flags* arguments is an OR of following flags:
 *   - MEMPOOL_F_NO_SPREAD: By default, objects addresses are spread
 *     between channels in RAM: the pool allocator will add padding
 *     between objects depending on the hardware configuration. See
 *     Memory alignment constraints for details. If this flag is set,
 *     the allocator will just align them to a cache line.
 *   - MEMPOOL_F_NO_CACHE_ALIGN: By default, the returned objects are
 *     cache-aligned. This flag removes this constraint, and no
 *     padding will be present between objects. This flag implies
 *     MEMPOOL_F_NO_SPREAD.
 *   - MEMPOOL_F_SP_PUT: If this flag is set, the default behavior
 *     when using rte_mempool_put() or rte_mempool_put_bulk() is
 *     "single-producer". Otherwise, it is "multi-producers".
 *   - MEMPOOL_F_SC_GET: If this flag is set, the default behavior
 *     when using rte_mempool_get() or rte_mempool_get_bulk() is
 *     "single-consumer". Otherwise, it is "multi-consumers".
 * @return
 *   The pointer to the new allocated mempool, on success. NULL on error
 *   with rte_errno set appropriately. Possible rte_errno values include:
 *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 *    - E_RTE_SECONDARY - function was called from a secondary process instance
 *    - EINVAL - cache size provided is too large
 *    - ENOSPC - the maximum number of memzones has already been allocated
 *    - EEXIST - a memzone with the same name already exists
 *    - ENOMEM - no appropriate memory area found in which to create memzone
 */
struct rte_mempool *
rte_dom0_mempool_create(const char *name, unsigned n, unsigned elt_size,
                unsigned cache_size, unsigned private_data_size,
                rte_mempool_ctor_t *mp_init, void *mp_init_arg,
                rte_mempool_obj_ctor_t *obj_init, void *obj_init_arg,
                int socket_id, unsigned flags);
#endif

/**
 * Dump the status of the mempool to the console.
 *
 * @param f
 *   A pointer to a file for output
 * @param mp
 *   A pointer to the mempool structure.
 */
void rte_mempool_dump(FILE *f, const struct rte_mempool *mp);

/**
 * @internal Put several objects back in the mempool; used internally.
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects).
 * @param n
 *   The number of objects to store back in the mempool, must be strictly
 *   positive.
 * @param is_mp
 *   Mono-producer (0) or multi-producers (1).
 */
static inline void __attribute__((always_inline))
__mempool_put_bulk(struct rte_mempool *mp, void * const *obj_table,
                    unsigned n, int is_mp)
{
#if RTE_MEMPOOL_CACHE_MAX_SIZE > 0
        struct rte_mempool_cache *cache;
        uint32_t index;
        void **cache_objs;
        unsigned lcore_id = rte_lcore_id();
        uint32_t cache_size = mp->cache_size;
        uint32_t flushthresh = mp->cache_flushthresh;
#endif /* RTE_MEMPOOL_CACHE_MAX_SIZE > 0 */

        /* increment stat now, adding in mempool always success */
        __MEMPOOL_STAT_ADD(mp, put, n);

#if RTE_MEMPOOL_CACHE_MAX_SIZE > 0
        /* cache is not enabled or single producer or non-EAL thread */
        if (unlikely(cache_size == 0 || is_mp == 0 ||
                     lcore_id >= RTE_MAX_LCORE))
                goto ring_enqueue;

        /* Go straight to ring if put would overflow mem allocated for cache */
        if (unlikely(n > RTE_MEMPOOL_CACHE_MAX_SIZE))
                goto ring_enqueue;

        cache = &mp->local_cache[lcore_id];
        cache_objs = &cache->objs[cache->len];

        /*
         * The cache follows the following algorithm
         *   1. Add the objects to the cache
         *   2. Anything greater than the cache min value (if it crosses the
         *   cache flush threshold) is flushed to the ring.
         */

        /* Add elements back into the cache */
        for (index = 0; index < n; ++index, obj_table++)
                cache_objs[index] = *obj_table;

        cache->len += n;

        if (cache->len >= flushthresh) {
                rte_ring_mp_enqueue_bulk(mp->ring, &cache->objs[cache_size],
                                cache->len - cache_size);
                cache->len = cache_size;
        }

        return;

ring_enqueue:
#endif /* RTE_MEMPOOL_CACHE_MAX_SIZE > 0 */

        /* push remaining objects in ring */
#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
        if (is_mp) {
                if (rte_ring_mp_enqueue_bulk(mp->ring, obj_table, n) < 0)
                        rte_panic("cannot put objects in mempool\n");
        }
        else {
                if (rte_ring_sp_enqueue_bulk(mp->ring, obj_table, n) < 0)
                        rte_panic("cannot put objects in mempool\n");
        }
#else
        if (is_mp)
                rte_ring_mp_enqueue_bulk(mp->ring, obj_table, n);
        else
                rte_ring_sp_enqueue_bulk(mp->ring, obj_table, n);
#endif
}


/**
 * Put several objects back in the mempool (multi-producers safe).
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects).
 * @param n
 *   The number of objects to add in the mempool from the obj_table.
 */
static inline void __attribute__((always_inline))
rte_mempool_mp_put_bulk(struct rte_mempool *mp, void * const *obj_table,
                        unsigned n)
{
        __mempool_check_cookies(mp, obj_table, n, 0);
        __mempool_put_bulk(mp, obj_table, n, 1);
}

/**
 * Put several objects back in the mempool (NOT multi-producers safe).
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects).
 * @param n
 *   The number of objects to add in the mempool from obj_table.
 */
static inline void
rte_mempool_sp_put_bulk(struct rte_mempool *mp, void * const *obj_table,
                        unsigned n)
{
        __mempool_check_cookies(mp, obj_table, n, 0);
        __mempool_put_bulk(mp, obj_table, n, 0);
}

/**
 * Put several objects back in the mempool.
 *
 * This function calls the multi-producer or the single-producer
 * version depending on the default behavior that was specified at
 * mempool creation time (see flags).
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects).
 * @param n
 *   The number of objects to add in the mempool from obj_table.
 */
static inline void __attribute__((always_inline))
rte_mempool_put_bulk(struct rte_mempool *mp, void * const *obj_table,
                     unsigned n)
{
        __mempool_check_cookies(mp, obj_table, n, 0);
        __mempool_put_bulk(mp, obj_table, n, !(mp->flags & MEMPOOL_F_SP_PUT));
}

/**
 * Put one object in the mempool (multi-producers safe).
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj
 *   A pointer to the object to be added.
 */
static inline void __attribute__((always_inline))
rte_mempool_mp_put(struct rte_mempool *mp, void *obj)
{
        rte_mempool_mp_put_bulk(mp, &obj, 1);
}

/**
 * Put one object back in the mempool (NOT multi-producers safe).
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj
 *   A pointer to the object to be added.
 */
static inline void __attribute__((always_inline))
rte_mempool_sp_put(struct rte_mempool *mp, void *obj)
{
        rte_mempool_sp_put_bulk(mp, &obj, 1);
}

/**
 * Put one object back in the mempool.
 *
 * This function calls the multi-producer or the single-producer
 * version depending on the default behavior that was specified at
 * mempool creation time (see flags).
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj
 *   A pointer to the object to be added.
 */
static inline void __attribute__((always_inline))
rte_mempool_put(struct rte_mempool *mp, void *obj)
{
        rte_mempool_put_bulk(mp, &obj, 1);
}

/**
 * @internal Get several objects from the mempool; used internally.
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects).
 * @param n
 *   The number of objects to get, must be strictly positive.
 * @param is_mc
 *   Mono-consumer (0) or multi-consumers (1).
 * @return
 *   - >=0: Success; number of objects supplied.
 *   - <0: Error; code of ring dequeue function.
 */
static inline int __attribute__((always_inline))
__mempool_get_bulk(struct rte_mempool *mp, void **obj_table,
                   unsigned n, int is_mc)
{
        int ret;
#if RTE_MEMPOOL_CACHE_MAX_SIZE > 0
        struct rte_mempool_cache *cache;
        uint32_t index, len;
        void **cache_objs;
        unsigned lcore_id = rte_lcore_id();
        uint32_t cache_size = mp->cache_size;

        /* cache is not enabled or single consumer */
        if (unlikely(cache_size == 0 || is_mc == 0 ||
                     n >= cache_size || lcore_id >= RTE_MAX_LCORE))
                goto ring_dequeue;

        cache = &mp->local_cache[lcore_id];
        cache_objs = cache->objs;

        /* Can this be satisfied from the cache? */
        if (cache->len < n) {
                /* No. Backfill the cache first, and then fill from it */
                uint32_t req = n + (cache_size - cache->len);

                /* How many do we require i.e. number to fill the cache + the request */
                ret = rte_ring_mc_dequeue_bulk(mp->ring, &cache->objs[cache->len], req);
                if (unlikely(ret < 0)) {
                        /*
                         * In the offchance that we are buffer constrained,
                         * where we are not able to allocate cache + n, go to
                         * the ring directly. If that fails, we are truly out of
                         * buffers.
                         */
                        goto ring_dequeue;
                }

                cache->len += req;
        }

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

        cache->len -= n;

        __MEMPOOL_STAT_ADD(mp, get_success, n);

        return 0;

ring_dequeue:
#endif /* RTE_MEMPOOL_CACHE_MAX_SIZE > 0 */

        /* get remaining objects from ring */
        if (is_mc)
                ret = rte_ring_mc_dequeue_bulk(mp->ring, obj_table, n);
        else
                ret = rte_ring_sc_dequeue_bulk(mp->ring, obj_table, n);

        if (ret < 0)
                __MEMPOOL_STAT_ADD(mp, get_fail, n);
        else
                __MEMPOOL_STAT_ADD(mp, get_success, n);

        return ret;
}

/**
 * Get several objects from the mempool (multi-consumers safe).
 *
 * If cache is enabled, objects will be retrieved first from cache,
 * subsequently from the common pool. Note that it can return -ENOENT when
 * the local cache and common pool are empty, even if cache from other
 * lcores are full.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects) that will be filled.
 * @param n
 *   The number of objects to get from mempool to obj_table.
 * @return
 *   - 0: Success; objects taken.
 *   - -ENOENT: Not enough entries in the mempool; no object is retrieved.
 */
static inline int __attribute__((always_inline))
rte_mempool_mc_get_bulk(struct rte_mempool *mp, void **obj_table, unsigned n)
{
        int ret;
        ret = __mempool_get_bulk(mp, obj_table, n, 1);
        if (ret == 0)
                __mempool_check_cookies(mp, obj_table, n, 1);
        return ret;
}

/**
 * Get several objects from the mempool (NOT multi-consumers safe).
 *
 * If cache is enabled, objects will be retrieved first from cache,
 * subsequently from the common pool. Note that it can return -ENOENT when
 * the local cache and common pool are empty, even if cache from other
 * lcores are full.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects) that will be filled.
 * @param n
 *   The number of objects to get from the mempool to obj_table.
 * @return
 *   - 0: Success; objects taken.
 *   - -ENOENT: Not enough entries in the mempool; no object is
 *     retrieved.
 */
static inline int __attribute__((always_inline))
rte_mempool_sc_get_bulk(struct rte_mempool *mp, void **obj_table, unsigned n)
{
        int ret;
        ret = __mempool_get_bulk(mp, obj_table, n, 0);
        if (ret == 0)
                __mempool_check_cookies(mp, obj_table, n, 1);
        return ret;
}

/**
 * Get several objects from the mempool.
 *
 * This function calls the multi-consumers or the single-consumer
 * version, depending on the default behaviour that was specified at
 * mempool creation time (see flags).
 *
 * If cache is enabled, objects will be retrieved first from cache,
 * subsequently from the common pool. Note that it can return -ENOENT when
 * the local cache and common pool are empty, even if cache from other
 * lcores are full.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_table
 *   A pointer to a table of void * pointers (objects) that will be filled.
 * @param n
 *   The number of objects to get from the mempool to obj_table.
 * @return
 *   - 0: Success; objects taken
 *   - -ENOENT: Not enough entries in the mempool; no object is retrieved.
 */
static inline int __attribute__((always_inline))
rte_mempool_get_bulk(struct rte_mempool *mp, void **obj_table, unsigned n)
{
        int ret;
        ret = __mempool_get_bulk(mp, obj_table, n,
                                 !(mp->flags & MEMPOOL_F_SC_GET));
        if (ret == 0)
                __mempool_check_cookies(mp, obj_table, n, 1);
        return ret;
}

/**
 * Get one object from the mempool (multi-consumers safe).
 *
 * If cache is enabled, objects will be retrieved first from cache,
 * subsequently from the common pool. Note that it can return -ENOENT when
 * the local cache and common pool are empty, even if cache from other
 * lcores are full.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_p
 *   A pointer to a void * pointer (object) that will be filled.
 * @return
 *   - 0: Success; objects taken.
 *   - -ENOENT: Not enough entries in the mempool; no object is retrieved.
 */
static inline int __attribute__((always_inline))
rte_mempool_mc_get(struct rte_mempool *mp, void **obj_p)
{
        return rte_mempool_mc_get_bulk(mp, obj_p, 1);
}

/**
 * Get one object from the mempool (NOT multi-consumers safe).
 *
 * If cache is enabled, objects will be retrieved first from cache,
 * subsequently from the common pool. Note that it can return -ENOENT when
 * the local cache and common pool are empty, even if cache from other
 * lcores are full.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_p
 *   A pointer to a void * pointer (object) that will be filled.
 * @return
 *   - 0: Success; objects taken.
 *   - -ENOENT: Not enough entries in the mempool; no object is retrieved.
 */
static inline int __attribute__((always_inline))
rte_mempool_sc_get(struct rte_mempool *mp, void **obj_p)
{
        return rte_mempool_sc_get_bulk(mp, obj_p, 1);
}

/**
 * Get one object from the mempool.
 *
 * This function calls the multi-consumers or the single-consumer
 * version, depending on the default behavior that was specified at
 * mempool creation (see flags).
 *
 * If cache is enabled, objects will be retrieved first from cache,
 * subsequently from the common pool. Note that it can return -ENOENT when
 * the local cache and common pool are empty, even if cache from other
 * lcores are full.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param obj_p
 *   A pointer to a void * pointer (object) that will be filled.
 * @return
 *   - 0: Success; objects taken.
 *   - -ENOENT: Not enough entries in the mempool; no object is retrieved.
 */
static inline int __attribute__((always_inline))
rte_mempool_get(struct rte_mempool *mp, void **obj_p)
{
        return rte_mempool_get_bulk(mp, obj_p, 1);
}

/**
 * Return the number of entries in the mempool.
 *
 * When cache is enabled, this function has to browse the length of
 * all lcores, so it should not be used in a data path, but only for
 * debug purposes.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @return
 *   The number of entries in the mempool.
 */
unsigned rte_mempool_count(const struct rte_mempool *mp);

/**
 * Return the number of free entries in the mempool ring.
 * i.e. how many entries can be freed back to the mempool.
 *
 * NOTE: This corresponds to the number of elements *allocated* from the
 * memory pool, not the number of elements in the pool itself. To count
 * the number elements currently available in the pool, use "rte_mempool_count"
 *
 * When cache is enabled, this function has to browse the length of
 * all lcores, so it should not be used in a data path, but only for
 * debug purposes.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @return
 *   The number of free entries in the mempool.
 */
static inline unsigned
rte_mempool_free_count(const struct rte_mempool *mp)
{
        return mp->size - rte_mempool_count(mp);
}

/**
 * Test if the mempool is full.
 *
 * When cache is enabled, this function has to browse the length of all
 * lcores, so it should not be used in a data path, but only for debug
 * purposes.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @return
 *   - 1: The mempool is full.
 *   - 0: The mempool is not full.
 */
static inline int
rte_mempool_full(const struct rte_mempool *mp)
{
        return !!(rte_mempool_count(mp) == mp->size);
}

/**
 * Test if the mempool is empty.
 *
 * When cache is enabled, this function has to browse the length of all
 * lcores, so it should not be used in a data path, but only for debug
 * purposes.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @return
 *   - 1: The mempool is empty.
 *   - 0: The mempool is not empty.
 */
static inline int
rte_mempool_empty(const struct rte_mempool *mp)
{
        return !!(rte_mempool_count(mp) == 0);
}

/**
 * Return the physical address of elt, which is an element of the pool mp.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @param elt
 *   A pointer (virtual address) to the element of the pool.
 * @return
 *   The physical address of the elt element.
 */
static inline phys_addr_t
rte_mempool_virt2phy(const struct rte_mempool *mp, const void *elt)
{
        if (rte_eal_has_hugepages()) {
                uintptr_t off;

                off = (const char *)elt - (const char *)mp->elt_va_start;
                return (mp->elt_pa[off >> mp->pg_shift] + (off & mp->pg_mask));
        } else {
                /*
                 * If huge pages are disabled, we cannot assume the
                 * memory region to be physically contiguous.
                 * Lookup for each element.
                 */
                return rte_mem_virt2phy(elt);
        }
}

/**
 * Check the consistency of mempool objects.
 *
 * Verify the coherency of fields in the mempool structure. Also check
 * that the cookies of mempool objects (even the ones that are not
 * present in pool) have a correct value. If not, a panic will occur.
 *
 * @param mp
 *   A pointer to the mempool structure.
 */
void rte_mempool_audit(const struct rte_mempool *mp);

/**
 * Return a pointer to the private data in an mempool structure.
 *
 * @param mp
 *   A pointer to the mempool structure.
 * @return
 *   A pointer to the private data.
 */
static inline void *rte_mempool_get_priv(struct rte_mempool *mp)
{
        return (char *)mp + MEMPOOL_HEADER_SIZE(mp, mp->pg_num);
}

/**
 * Dump the status of all mempools on the console
 *
 * @param f
 *   A pointer to a file for output
 */
void rte_mempool_list_dump(FILE *f);

/**
 * Search a mempool from its name
 *
 * @param name
 *   The name of the mempool.
 * @return
 *   The pointer to the mempool matching the name, or NULL if not found.
 *   NULL on error
 *   with rte_errno set appropriately. Possible rte_errno values include:
 *    - ENOENT - required entry not available to return.
 *
 */
struct rte_mempool *rte_mempool_lookup(const char *name);

/**
 * Get the header, trailer and total size of a mempool element.
 *
 * Given a desired size of the mempool element and mempool flags,
 * calculates header, trailer, body and total sizes of the mempool object.
 *
 * @param elt_size
 *   The size of each element.
 * @param flags
 *   The flags used for the mempool creation.
 *   Consult rte_mempool_create() for more information about possible values.
 *   The size of each element.
 * @param sz
 *   The calculated detailed size the mempool object. May be NULL.
 * @return
 *   Total size of the mempool object.
 */
uint32_t rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags,
        struct rte_mempool_objsz *sz);

/**
 * Get the size of memory required to store mempool elements.
 *
 * Calculate the maximum amount of memory required to store given number
 * of objects. Assume that the memory buffer will be aligned at page
 * boundary.
 *
 * Note that if object size is bigger then page size, then it assumes
 * that pages are grouped in subsets of physically continuous pages big
 * enough to store at least one object.
 *
 * @param elt_num
 *   Number of elements.
 * @param elt_sz
 *   The size of each element.
 * @param pg_shift
 *   LOG2 of the physical pages size.
 * @return
 *   Required memory size aligned at page boundary.
 */
size_t rte_mempool_xmem_size(uint32_t elt_num, size_t elt_sz,
        uint32_t pg_shift);

/**
 * Get the size of memory required to store mempool elements.
 *
 * Calculate how much memory would be actually required with the given
 * memory footprint to store required number of objects.
 *
 * @param vaddr
 *   Virtual address of the externally allocated memory buffer.
 *   Will be used to store mempool objects.
 * @param elt_num
 *   Number of elements.
 * @param elt_sz
 *   The size of each element.
 * @param paddr
 *   Array of physical addresses of the pages that comprises given memory
 *   buffer.
 * @param pg_num
 *   Number of elements in the paddr array.
 * @param pg_shift
 *   LOG2 of the physical pages size.
 * @return
 *   On success, the number of bytes needed to store given number of
 *   objects, aligned to the given page size. If the provided memory
 *   buffer is too small, return a negative value whose absolute value
 *   is the actual number of elements that can be stored in that buffer.
 */
ssize_t rte_mempool_xmem_usage(void *vaddr, uint32_t elt_num, size_t elt_sz,
        const phys_addr_t paddr[], uint32_t pg_num, uint32_t pg_shift);

/**
 * Walk list of all memory pools
 *
 * @param func
 *   Iterator function
 * @param arg
 *   Argument passed to iterator
 */
void rte_mempool_walk(void (*func)(const struct rte_mempool *, void *arg),
                      void *arg);

#ifdef __cplusplus
}
#endif

#endif /* _RTE_MEMPOOL_H_ */