[dpdk-dev] [PATCH v6 1/5] mempool: support external handler

[Jan Viktorin]

Hello David,

the rename s/handler/ops/ has a lot of residues. Sorry for that :). I tried to
mark most of them. Otherwise, I couldn't see many more serious issues for now.

Just, note the s/pool/priv/ rename suggestion.

On Wed,  1 Jun 2016 17:19:54 +0100
David Hunt <david.hunt at intel.com> wrote:

> Until now, the objects stored in a mempool were internally stored in a
> ring. This patch introduces the possibility to register external handlers
> replacing the ring.
> 
> The default behavior remains unchanged, but calling the new function
> rte_mempool_set_handler() right after rte_mempool_create_empty() allows
> the user to change the handler that will be used when populating
> the mempool.
> 
> v7 changes:
>   * Moved the flags handling from rte_mempool_create_empty to
>     rte_mempool_create, as it's only there for backward compatibility
>   * Various comment additions and cleanup
>   * Renamed rte_mempool_handler to rte_mempool_ops
>   * Added a union for *pool and u64 pool_id in struct rte_mempool
> 
> v6 changes:
>   * split the original patch into a few parts for easier review.
>   * rename functions with _ext_ to _ops_.
>   * addressed some review comments
>   * renamed put and get functions to enqueue and dequeue
>   * renamed rte_mempool_handler struct to rte_mempool_handler_ops
>   * changed occurences of rte_mempool_handler_ops to const, as they
>     contain function pointers (security)
>   * added some extra comments
> 
> v5 changes: rebasing on top of 35 patch set mempool work.
> 
> Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
> Signed-off-by: David Hunt <david.hunt at intel.com>
> ---
>  lib/librte_mempool/Makefile              |   1 +
>  lib/librte_mempool/rte_mempool.c         |  71 ++++------
>  lib/librte_mempool/rte_mempool.h         | 235 ++++++++++++++++++++++++++++---
>  lib/librte_mempool/rte_mempool_handler.c | 141 +++++++++++++++++++
>  4 files changed, 384 insertions(+), 64 deletions(-)
>  create mode 100644 lib/librte_mempool/rte_mempool_handler.c
> 
> diff --git a/lib/librte_mempool/Makefile b/lib/librte_mempool/Makefile
> index 43423e0..793745f 100644
> --- a/lib/librte_mempool/Makefile
> +++ b/lib/librte_mempool/Makefile
> @@ -42,6 +42,7 @@ LIBABIVER := 2
>  
>  # all source are stored in SRCS-y
>  SRCS-$(CONFIG_RTE_LIBRTE_MEMPOOL) +=  rte_mempool.c
> +SRCS-$(CONFIG_RTE_LIBRTE_MEMPOOL) +=  rte_mempool_handler.c
>  # install includes
>  SYMLINK-$(CONFIG_RTE_LIBRTE_MEMPOOL)-include := rte_mempool.h
>  
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index b54de43..9f34d30 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -148,7 +148,7 @@ mempool_add_elem(struct rte_mempool *mp, void *obj, phys_addr_t physaddr)
>  #endif
>  
>  	/* enqueue in ring */
> -	rte_ring_sp_enqueue(mp->ring, obj);
> +	rte_mempool_ops_enqueue_bulk(mp, &obj, 1);
>  }
>  
>  /* call obj_cb() for each mempool element */
> @@ -303,40 +303,6 @@ rte_mempool_xmem_usage(__rte_unused void *vaddr, uint32_t elt_num,
>  	return (size_t)paddr_idx << pg_shift;
>  }
>  
> -/* create the internal ring */
> -static int
> -rte_mempool_ring_create(struct rte_mempool *mp)
> -{
> -	int rg_flags = 0, ret;
> -	char rg_name[RTE_RING_NAMESIZE];
> -	struct rte_ring *r;
> -
> -	ret = snprintf(rg_name, sizeof(rg_name),
> -		RTE_MEMPOOL_MZ_FORMAT, mp->name);
> -	if (ret < 0 || ret >= (int)sizeof(rg_name))
> -		return -ENAMETOOLONG;
> -
> -	/* ring flags */
> -	if (mp->flags & MEMPOOL_F_SP_PUT)
> -		rg_flags |= RING_F_SP_ENQ;
> -	if (mp->flags & MEMPOOL_F_SC_GET)
> -		rg_flags |= RING_F_SC_DEQ;
> -
> -	/* Allocate the ring that will be used to store objects.
> -	 * Ring functions will return appropriate errors if we are
> -	 * running as a secondary process etc., so no checks made
> -	 * in this function for that condition.
> -	 */
> -	r = rte_ring_create(rg_name, rte_align32pow2(mp->size + 1),
> -		mp->socket_id, rg_flags);
> -	if (r == NULL)
> -		return -rte_errno;
> -
> -	mp->ring = r;
> -	mp->flags |= MEMPOOL_F_RING_CREATED;
> -	return 0;
> -}
> -
>  /* free a memchunk allocated with rte_memzone_reserve() */
>  static void
>  rte_mempool_memchunk_mz_free(__rte_unused struct rte_mempool_memhdr *memhdr,
> @@ -354,7 +320,7 @@ rte_mempool_free_memchunks(struct rte_mempool *mp)
>  	void *elt;
>  
>  	while (!STAILQ_EMPTY(&mp->elt_list)) {
> -		rte_ring_sc_dequeue(mp->ring, &elt);
> +		rte_mempool_ops_dequeue_bulk(mp, &elt, 1);
>  		(void)elt;
>  		STAILQ_REMOVE_HEAD(&mp->elt_list, next);
>  		mp->populated_size--;
> @@ -383,13 +349,16 @@ rte_mempool_populate_phys(struct rte_mempool *mp, char *vaddr,
>  	unsigned i = 0;
>  	size_t off;
>  	struct rte_mempool_memhdr *memhdr;
> -	int ret;
>  
>  	/* create the internal ring if not already done */
>  	if ((mp->flags & MEMPOOL_F_RING_CREATED) == 0) {
> -		ret = rte_mempool_ring_create(mp);
> -		if (ret < 0)
> -			return ret;
> +		rte_errno = 0;
> +		mp->pool = rte_mempool_ops_alloc(mp);
> +		if (mp->pool == NULL) {
> +			if (rte_errno == 0)
> +				return -EINVAL;
> +			return -rte_errno;

Are you sure the rte_errno is a positive value?

> +		}
>  	}
>  
>  	/* mempool is already populated */
> @@ -703,7 +672,7 @@ rte_mempool_free(struct rte_mempool *mp)
>  	rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
>  
>  	rte_mempool_free_memchunks(mp);
> -	rte_ring_free(mp->ring);
> +	rte_mempool_ops_free(mp);
>  	rte_memzone_free(mp->mz);
>  }
>  
> @@ -815,6 +784,20 @@ rte_mempool_create_empty(const char *name, unsigned n, unsigned elt_size,
>  		RTE_PTR_ADD(mp, MEMPOOL_HEADER_SIZE(mp, 0));
>  
>  	te->data = mp;
> +
> +	/*
> +	 * Since we have 4 combinations of the SP/SC/MP/MC examine the flags to
> +	 * set the correct index into the handler table.
> +	 */
> +	if (flags & (MEMPOOL_F_SP_PUT | MEMPOOL_F_SC_GET))
> +		rte_mempool_set_handler(mp, "ring_sp_sc");
> +	else if (flags & MEMPOOL_F_SP_PUT)
> +		rte_mempool_set_handler(mp, "ring_sp_mc");
> +	else if (flags & MEMPOOL_F_SC_GET)
> +		rte_mempool_set_handler(mp, "ring_mp_sc");
> +	else
> +		rte_mempool_set_handler(mp, "ring_mp_mc");
> +
>  	rte_rwlock_write_lock(RTE_EAL_TAILQ_RWLOCK);
>  	TAILQ_INSERT_TAIL(mempool_list, te, next);
>  	rte_rwlock_write_unlock(RTE_EAL_TAILQ_RWLOCK);
> @@ -930,7 +913,7 @@ rte_mempool_count(const struct rte_mempool *mp)
>  	unsigned count;
>  	unsigned lcore_id;
>  
> -	count = rte_ring_count(mp->ring);
> +	count = rte_mempool_ops_get_count(mp);
>  
>  	if (mp->cache_size == 0)
>  		return count;
> @@ -1123,7 +1106,7 @@ rte_mempool_dump(FILE *f, struct rte_mempool *mp)
>  
>  	fprintf(f, "mempool <%s>@%p\n", mp->name, mp);
>  	fprintf(f, "  flags=%x\n", mp->flags);
> -	fprintf(f, "  ring=<%s>@%p\n", mp->ring->name, mp->ring);
> +	fprintf(f, "  pool=%p\n", mp->pool);
>  	fprintf(f, "  phys_addr=0x%" PRIx64 "\n", mp->mz->phys_addr);
>  	fprintf(f, "  nb_mem_chunks=%u\n", mp->nb_mem_chunks);
>  	fprintf(f, "  size=%"PRIu32"\n", mp->size);
> @@ -1144,7 +1127,7 @@ rte_mempool_dump(FILE *f, struct rte_mempool *mp)
>  	}
>  
>  	cache_count = rte_mempool_dump_cache(f, mp);
> -	common_count = rte_ring_count(mp->ring);
> +	common_count = rte_mempool_ops_get_count(mp);
>  	if ((cache_count + common_count) > mp->size)
>  		common_count = mp->size - cache_count;
>  	fprintf(f, "  common_pool_count=%u\n", common_count);
> diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> index 60339bd..b659565 100644
> --- a/lib/librte_mempool/rte_mempool.h
> +++ b/lib/librte_mempool/rte_mempool.h
> @@ -67,6 +67,7 @@
>  #include <inttypes.h>
>  #include <sys/queue.h>
>  
> +#include <rte_spinlock.h>
>  #include <rte_log.h>
>  #include <rte_debug.h>
>  #include <rte_lcore.h>
> @@ -204,9 +205,13 @@ struct rte_mempool_memhdr {
>  struct rte_mempool {
>  	char name[RTE_MEMPOOL_NAMESIZE]; /**< Name of mempool. */
>  	struct rte_ring *ring;           /**< Ring to store objects. */
> +	union {
> +		void *pool;              /**< Ring or pool to store objects */

What about calling this pdata or priv? I think, it can improve some doc comments.
Describing a "pool" may refer to both the rte_mempool itself or to the mp->pool
pointer. The "priv" would help to understand the code a bit.

Then the rte_mempool_alloc_t can be called rte_mempool_priv_alloc_t. Or something
similar. It's than clear enough, what the function should do...

> +		uint64_t *pool_id;       /**< External mempool identifier */

Why is pool_id a pointer? Is it a typo? I've understood it should be 64b wide
from the discussion (Olivier, Jerin, David):

| >>> something like below,
| >>> union {
| >>> 	void *pool;
| >>> 	uint64_t val;
| >>> 	uint8_t extra_mem[16] // available free bytes in fast path cache line
| >>>
| >>> }  
| >>
| >> Something for the future, perhaps? Will the 8-bits in the flags suffice for
| >> now?  
| > 
| > OK. But simple anonymous union for same type should be OK add now? Not
| > much change I believe, If its difficult then postpone it
| > 
| > union {
| > 	void *pool;
| > 	uint64_t val;
| > }  
|
| I'm ok with the simple union with (void *) and (uint64_t).
| Maybe "val" should be replaced by something more appropriate.
| Is "pool_id" a better name?

> +	};
>  	const struct rte_memzone *mz;    /**< Memzone where pool is allocated */
>  	int flags;                       /**< Flags of the mempool. */
> -	int socket_id;                   /**< Socket id passed at mempool creation. */
> +	int socket_id;                   /**< Socket id passed at create */
>  	uint32_t size;                   /**< Max size of the mempool. */
>  	uint32_t cache_size;             /**< Size of per-lcore local cache. */
>  	uint32_t cache_flushthresh;
> @@ -217,6 +222,14 @@ struct rte_mempool {
>  	uint32_t trailer_size;           /**< Size of trailer (after elt). */
>  
>  	unsigned private_data_size;      /**< Size of private data. */
> +	/**
> +	 * Index into rte_mempool_handler_table array of mempool handler ops

s/rte_mempool_handler_table/rte_mempool_ops_table/

> +	 * structs, which contain callback function pointers.
> +	 * We're using an index here rather than pointers to the callbacks
> +	 * to facilitate any secondary processes that may want to use
> +	 * this mempool.
> +	 */
> +	int32_t handler_idx;

s/handler_idx/ops_idx/

What about ops_index? Not a big deal...

>  
>  	struct rte_mempool_cache *local_cache; /**< Per-lcore local cache */
>  
> @@ -325,6 +338,199 @@ void rte_mempool_check_cookies(const struct rte_mempool *mp,
>  #define __mempool_check_cookies(mp, obj_table_const, n, free) do {} while(0)
>  #endif /* RTE_LIBRTE_MEMPOOL_DEBUG */
>  
> +#define RTE_MEMPOOL_HANDLER_NAMESIZE 32 /**< Max length of handler name. */
> +
> +/**
> + * typedef for allocating the external pool.

What about:

function prototype to provide an implementation specific data

> + * The handler's alloc function does whatever it needs to do to grab memory
> + * for this handler, and sets the *pool opaque pointer in the rte_mempool
> + * struct. In the default handler, *pool points to a ring,in other handlers,

What about:

The function should provide a memory heap representation or another private data
used for allocation by the rte_mempool_ops. E.g. the default ops provides an
instance of the rte_ring for this purpose.

> + * it will mostlikely point to a different type of data structure.
> + * It will be transparent to the application programmer.

I'd add something like this:

The function should not touch the given *mp instance.

...because it's goal is NOT to set the mp->pool, this is done by the
rte_mempool_populate_phys - the caller of this rte_mempool_ops_alloc.

This is why I've suggested to pass the rte_mempool as const in the v5.
Is there any reason to modify the rte_mempool contents by the implementation?
I think, we just need to read the flags, socket_id, etc.

> + */
> +typedef void *(*rte_mempool_alloc_t)(struct rte_mempool *mp);
> +
> +/** Free the external pool opaque data (that pointed to by *pool) */

What about:

/** Free the opaque private data stored in the mp->pool pointer. */

> +typedef void (*rte_mempool_free_t)(void *p);
> +
> +/**
> + * Put an object in the external pool.
> + * The *p pointer is the opaque data for a given mempool handler (ring,
> + * array, linked list, etc)

The obj_table is not documented. Is it really a table? I'd called an array instead.

> + */
> +typedef int (*rte_mempool_put_t)(void *p, void * const *obj_table, unsigned n);

unsigned int

> +
> +/** Get an object from the external pool. */
> +typedef int (*rte_mempool_get_t)(void *p, void **obj_table, unsigned n);

unsigned int

> +
> +/** Return the number of available objects in the external pool. */

Is the number of available objects or the total number of all objects
(so probably a constant value)?

> +typedef unsigned (*rte_mempool_get_count)(void *p);

Should it be const void *p?

> +
> +/** Structure defining a mempool handler. */

What about:

/** Structure defining mempool operations. */

> +struct rte_mempool_ops {
> +	char name[RTE_MEMPOOL_HANDLER_NAMESIZE]; /**< Name of mempool handler */

s/RTE_MEMPOOL_HANDLER_NAMESIZE/RTE_MEMPOOL_OPS_NAMESIZE/

> +	rte_mempool_alloc_t alloc;       /**< Allocate the external pool. */

What about:

Allocate the private data for this rte_mempool_ops.

> +	rte_mempool_free_t free;         /**< Free the external pool. */
> +	rte_mempool_put_t put;           /**< Put an object. */
> +	rte_mempool_get_t get;           /**< Get an object. */
> +	rte_mempool_get_count get_count; /**< Get the number of available objs. */
> +} __rte_cache_aligned;
> +
> +#define RTE_MEMPOOL_MAX_HANDLER_IDX 16  /**< Max registered handlers */

s/RTE_MEMPOOL_MAX_HANDLER_IDX/RTE_MEMPOOL_MAX_OPS_IDX/

> +
> +/**
> + * Structure storing the table of registered handlers, each of which contain
> + * the function pointers for the mempool handler functions.
> + * Each process has it's own storage for this handler struct aray so that
> + * the mempools can be shared across primary and secondary processes.
> + * The indices used to access the array are valid across processes, whereas
> + * any function pointers stored directly in the mempool struct would not be.
> + * This results in us simply having "handler_idx" in the mempool struct.
> + */
> +struct rte_mempool_handler_table {

s/rte_mempool_handler_table/rte_mempool_ops_table/

> +	rte_spinlock_t sl;     /**< Spinlock for add/delete. */
> +	uint32_t num_handlers; /**< Number of handlers in the table. */

s/num_handlers/num_ops/

> +	/**
> +	 * Storage for all possible handlers.
> +	 */
> +	struct rte_mempool_ops handler_ops[RTE_MEMPOOL_MAX_HANDLER_IDX];

s/handler_ops/ops/

> +} __rte_cache_aligned;
> +
> +/** Array of registered handlers */
> +extern struct rte_mempool_handler_table rte_mempool_handler_table;

s/rte_mempool_handler_table/rte_mempool_ops_table/

> +
> +/**
> + * @internal Get the mempool handler from its index.
> + *
> + * @param handler_idx
> + *   The index of the handler in the handler table. It must be a valid
> + *   index: (0 <= idx < num_handlers).
> + * @return
> + *   The pointer to the handler in the table.
> + */
> +static inline struct rte_mempool_ops *
> +rte_mempool_handler_get(int handler_idx)

rte_mempool_ops_get(int ops_idx)

> +{
> +	return &rte_mempool_handler_table.handler_ops[handler_idx];
> +}
> +
> +/**
> + * @internal wrapper for external mempool manager alloc callback.
> + *
> + * @param mp
> + *   Pointer to the memory pool.
> + * @return
> + *   The opaque pointer to the external pool.
> + */
> +void *
> +rte_mempool_ops_alloc(struct rte_mempool *mp);
> +
> +/**
> + * @internal wrapper for external mempool manager get callback.
> + *
> + * @param mp
> + *   Pointer to the memory pool.
> + * @param obj_table
> + *   Pointer to a table of void * pointers (objects).
> + * @param n
> + *   Number of objects to get.
> + * @return
> + *   - 0: Success; got n objects.
> + *   - <0: Error; code of handler get function.
> + */
> +static inline int
> +rte_mempool_ops_dequeue_bulk(struct rte_mempool *mp,
> +		void **obj_table, unsigned n)
> +{
> +	struct rte_mempool_ops *handler;

*ops

> +
> +	handler = rte_mempool_handler_get(mp->handler_idx);
> +	return handler->get(mp->pool, obj_table, n);
> +}
> +
> +/**
> + * @internal wrapper for external mempool manager put callback.
> + *
> + * @param mp
> + *   Pointer to the memory pool.
> + * @param obj_table
> + *   Pointer to a table of void * pointers (objects).
> + * @param n
> + *   Number of objects to put.
> + * @return
> + *   - 0: Success; n objects supplied.
> + *   - <0: Error; code of handler put function.
> + */
> +static inline int
> +rte_mempool_ops_enqueue_bulk(struct rte_mempool *mp, void * const *obj_table,
> +		unsigned n)
> +{
> +	struct rte_mempool_ops *handler;

*ops

> +
> +	handler = rte_mempool_handler_get(mp->handler_idx);
> +	return handler->put(mp->pool, obj_table, n);
> +}
> +
> +/**
> + * @internal wrapper for external mempool manager get_count callback.
> + *
> + * @param mp
> + *   Pointer to the memory pool.
> + * @return
> + *   The number of available objects in the external pool.
> + */
> +unsigned
> +rte_mempool_ops_get_count(const struct rte_mempool *mp);
> +
> +/**
> + * @internal wrapper for external mempool manager free callback.
> + *
> + * @param mp
> + *   Pointer to the memory pool.
> + */
> +void
> +rte_mempool_ops_free(struct rte_mempool *mp);
> +
> +/**
> + * Set the handler of a mempool
> + *
> + * This can only be done on a mempool that is not populated, i.e. just after
> + * a call to rte_mempool_create_empty().
> + *
> + * @param mp
> + *   Pointer to the memory pool.
> + * @param name
> + *   Name of the handler.
> + * @return
> + *   - 0: Sucess; the new handler is configured.
> + *   - EINVAL - Invalid handler name provided
> + *   - EEXIST - mempool already has a handler assigned

They are returned as -EINVAL and -EEXIST.

IMHO, using "-" here is counter-intuitive:

 - EINVAL

does it mean a positive with "-" or negative value?

> + */
> +int
> +rte_mempool_set_handler(struct rte_mempool *mp, const char *name);

rte_mempool_set_ops

What about rte_mempool_set_ops_byname? Not a big deal...

> +
> +/**
> + * Register an external pool handler.

Register mempool operations

> + *
> + * @param h
> + *   Pointer to the external pool handler
> + * @return
> + *   - >=0: Sucess; return the index of the handler in the table.
> + *   - EINVAL - missing callbacks while registering handler
> + *   - ENOSPC - the maximum number of handlers has been reached

- -EINVAL
- -ENOSPC

> + */
> +int rte_mempool_handler_register(const struct rte_mempool_ops *h);

rte_mempool_ops_register

> +
> +/**
> + * Macro to statically register an external pool handler.

What about adding:

Note that the rte_mempool_ops_register fails silently here when
more then RTE_MEMPOOL_MAX_OPS_IDX is registered.

> + */
> +#define MEMPOOL_REGISTER_HANDLER(h)	

MEMPOOL_REGISTER_OPS
				\
> +	void mp_hdlr_init_##h(void);					\
> +	void __attribute__((constructor, used)) mp_hdlr_init_##h(void)	\
> +	{								\
> +		rte_mempool_handler_register(&h);			\
> +	}
> +
>  /**
>   * An object callback function for mempool.
>   *
> @@ -774,7 +980,7 @@ __mempool_put_bulk(struct rte_mempool *mp, void * const *obj_table,
>  	cache->len += n;
>  
>  	if (cache->len >= flushthresh) {
> -		rte_ring_mp_enqueue_bulk(mp->ring, &cache->objs[cache_size],
> +		rte_mempool_ops_enqueue_bulk(mp, &cache->objs[cache_size],
>  				cache->len - cache_size);
>  		cache->len = cache_size;
>  	}
> @@ -785,19 +991,10 @@ ring_enqueue:
>  
>  	/* 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");
> -	}
> +	if (rte_mempool_ops_enqueue_bulk(mp, 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);
> +	rte_mempool_ops_enqueue_bulk(mp, obj_table, n);
>  #endif
>  }
>  
> @@ -922,7 +1119,7 @@ rte_mempool_put(struct rte_mempool *mp, void *obj)
>   */
>  static inline int __attribute__((always_inline))
>  __mempool_get_bulk(struct rte_mempool *mp, void **obj_table,
> -		   unsigned n, int is_mc)
> +		   unsigned n, __rte_unused int is_mc)

unsigned int

>  {
>  	int ret;
>  	struct rte_mempool_cache *cache;
> @@ -945,7 +1142,8 @@ __mempool_get_bulk(struct rte_mempool *mp, void **obj_table,
>  		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);
> +		ret = rte_mempool_ops_dequeue_bulk(mp,
> +			&cache->objs[cache->len], req);
>  		if (unlikely(ret < 0)) {
>  			/*
>  			 * In the offchance that we are buffer constrained,
> @@ -972,10 +1170,7 @@ __mempool_get_bulk(struct rte_mempool *mp, void **obj_table,
>  ring_dequeue:
>  
>  	/* 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);
> +	ret = rte_mempool_ops_dequeue_bulk(mp, obj_table, n);
>  
>  	if (ret < 0)
>  		__MEMPOOL_STAT_ADD(mp, get_fail, n);
> diff --git a/lib/librte_mempool/rte_mempool_handler.c b/lib/librte_mempool/rte_mempool_handler.c
> new file mode 100644
> index 0000000..ed85d65
> --- /dev/null
> +++ b/lib/librte_mempool/rte_mempool_handler.c

rte_mempool_ops.c

> @@ -0,0 +1,141 @@
> +/*-
> + *   BSD LICENSE
> + *
> + *   Copyright(c) 2016 Intel Corporation. All rights reserved.
> + *   Copyright(c) 2016 6WIND S.A.
> + *   All rights reserved.
> + *
> + *   Redistribution and use in source and binary forms, with or without
> + *   modification, are permitted provided that the following conditions
> + *   are met:
> + *
> + *     * Redistributions of source code must retain the above copyright
> + *       notice, this list of conditions and the following disclaimer.
> + *     * Redistributions in binary form must reproduce the above copyright
> + *       notice, this list of conditions and the following disclaimer in
> + *       the documentation and/or other materials provided with the
> + *       distribution.
> + *     * Neither the name of Intel Corporation nor the names of its
> + *       contributors may be used to endorse or promote products derived
> + *       from this software without specific prior written permission.
> + *
> + *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
> + *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> + *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
> + *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
> + *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
> + *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> + *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
> + *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
> + *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
> + *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <stdio.h>
> +#include <string.h>
> +
> +#include <rte_mempool.h>
> +
> +/* indirect jump table to support external memory pools */
> +struct rte_mempool_handler_table rte_mempool_handler_table = {

rte_mempool_ops_table

> +	.sl =  RTE_SPINLOCK_INITIALIZER ,
> +	.num_handlers = 0

num_ops

> +};
> +
> +/* add a new handler in rte_mempool_handler_table, return its index */
> +int
> +rte_mempool_handler_register(const struct rte_mempool_ops *h)
> +{
> +	struct rte_mempool_ops *handler;

*ops

> +	int16_t handler_idx;

ops_idx

> +
> +	rte_spinlock_lock(&rte_mempool_handler_table.sl);
> +
> +	if (rte_mempool_handler_table.num_handlers >=
> +			RTE_MEMPOOL_MAX_HANDLER_IDX) {
> +		rte_spinlock_unlock(&rte_mempool_handler_table.sl);
> +		RTE_LOG(ERR, MEMPOOL,
> +			"Maximum number of mempool handlers exceeded\n");
> +		return -ENOSPC;
> +	}
> +
> +	if (h->put == NULL || h->get == NULL || h->get_count == NULL) {
> +		rte_spinlock_unlock(&rte_mempool_handler_table.sl);
> +		RTE_LOG(ERR, MEMPOOL,
> +			"Missing callback while registering mempool handler\n");
> +		return -EINVAL;
> +	}
> +
> +	handler_idx = rte_mempool_handler_table.num_handlers++;
> +	handler = &rte_mempool_handler_table.handler_ops[handler_idx];
> +	snprintf(handler->name, sizeof(handler->name), "%s", h->name);
> +	handler->alloc = h->alloc;
> +	handler->put = h->put;
> +	handler->get = h->get;
> +	handler->get_count = h->get_count;
> +
> +	rte_spinlock_unlock(&rte_mempool_handler_table.sl);
> +
> +	return handler_idx;
> +}
> +
> +/* wrapper to allocate an external pool handler */
> +void *
> +rte_mempool_ops_alloc(struct rte_mempool *mp)
> +{
> +	struct rte_mempool_ops *handler;

*ops

> +
> +	handler = rte_mempool_handler_get(mp->handler_idx);
> +	if (handler->alloc == NULL)
> +		return NULL;
> +	return handler->alloc(mp);
> +}
> +
> +/* wrapper to free an external pool handler */
> +void
> +rte_mempool_ops_free(struct rte_mempool *mp)
> +{
> +	struct rte_mempool_ops *handler;

*ops

> +
> +	handler = rte_mempool_handler_get(mp->handler_idx);
> +	if (handler->free == NULL)
> +		return;
> +	return handler->free(mp);
> +}
> +
> +/* wrapper to get available objects in an external pool handler */
> +unsigned int
> +rte_mempool_ops_get_count(const struct rte_mempool *mp)
> +{
> +	struct rte_mempool_ops *handler;

*ops

> +
> +	handler = rte_mempool_handler_get(mp->handler_idx);
> +	return handler->get_count(mp->pool);
> +}
> +
> +/* sets a handler previously registered by rte_mempool_handler_register */
> +int
> +rte_mempool_set_handler(struct rte_mempool *mp, const char *name)
> +{
> +	struct rte_mempool_ops *handler = NULL;

*ops

> +	unsigned i;
> +
> +	/* too late, the mempool is already populated */
> +	if (mp->flags & MEMPOOL_F_RING_CREATED)
> +		return -EEXIST;
> +
> +	for (i = 0; i < rte_mempool_handler_table.num_handlers; i++) {
> +		if (!strcmp(name,
> +				rte_mempool_handler_table.handler_ops[i].name)) {
> +			handler = &rte_mempool_handler_table.handler_ops[i];
> +			break;
> +		}
> +	}
> +
> +	if (handler == NULL)
> +		return -EINVAL;
> +
> +	mp->handler_idx = i;
> +	return 0;
> +}

Regards
Jan