#include <stdio.h>
#include <stdint.h>
#include <sys/queue.h>
#include <errno.h>
#include <rte_common.h>
#include <rte_memory.h>
#include <rte_lcore.h>
#include <rte_atomic.h>
#include <rte_branch_prediction.h>

Data Structures
struct	rte_ring
struct	rte_ring::prod
struct	rte_ring::cons

Macros
#define	RTE_RING_NAMESIZE 32
#define	RTE_RING_PAUSE_REP_COUNT 0
#define	RING_F_SP_ENQ 0x0001
#define	RING_F_SC_DEQ 0x0002
#define	RTE_RING_QUOT_EXCEED (1 << 31)
#define	RTE_RING_SZ_MASK (unsigned)(0x0fffffff)

Functions
ssize_t	rte_ring_get_memsize (unsigned count)
int	rte_ring_init (struct rte_ring r, const char name, unsigned count, unsigned flags)
struct rte_ring *	rte_ring_create (const char *name, unsigned count, int socket_id, unsigned flags)
int	rte_ring_set_water_mark (struct rte_ring *r, unsigned count)
void	rte_ring_dump (FILE f, const struct rte_ring r)
static int	rte_ring_mp_enqueue_bulk (struct rte_ring r, void const *obj_table, unsigned n)
static int	rte_ring_sp_enqueue_bulk (struct rte_ring r, void const *obj_table, unsigned n)
static int	rte_ring_enqueue_bulk (struct rte_ring r, void const *obj_table, unsigned n)
static int	rte_ring_mp_enqueue (struct rte_ring r, void obj)
static int	rte_ring_sp_enqueue (struct rte_ring r, void obj)
static int	rte_ring_enqueue (struct rte_ring r, void obj)
static int	rte_ring_mc_dequeue_bulk (struct rte_ring r, void *obj_table, unsigned n)
static int	rte_ring_sc_dequeue_bulk (struct rte_ring r, void *obj_table, unsigned n)
static int	rte_ring_dequeue_bulk (struct rte_ring r, void *obj_table, unsigned n)
static int	rte_ring_mc_dequeue (struct rte_ring r, void *obj_p)
static int	rte_ring_sc_dequeue (struct rte_ring r, void *obj_p)
static int	rte_ring_dequeue (struct rte_ring r, void *obj_p)
static int	rte_ring_full (const struct rte_ring *r)
static int	rte_ring_empty (const struct rte_ring *r)
static unsigned	rte_ring_count (const struct rte_ring *r)
static unsigned	rte_ring_free_count (const struct rte_ring *r)
void	rte_ring_list_dump (FILE *f)
struct rte_ring *	rte_ring_lookup (const char *name)
static unsigned	rte_ring_mp_enqueue_burst (struct rte_ring r, void const *obj_table, unsigned n)
static unsigned	rte_ring_sp_enqueue_burst (struct rte_ring r, void const *obj_table, unsigned n)
static unsigned	rte_ring_enqueue_burst (struct rte_ring r, void const *obj_table, unsigned n)
static unsigned	rte_ring_mc_dequeue_burst (struct rte_ring r, void *obj_table, unsigned n)
static unsigned	rte_ring_sc_dequeue_burst (struct rte_ring r, void *obj_table, unsigned n)
static unsigned	rte_ring_dequeue_burst (struct rte_ring r, void *obj_table, unsigned n)

Detailed Description

RTE Ring

The Ring Manager is a fixed-size queue, implemented as a table of pointers. Head and tail pointers are modified atomically, allowing concurrent access to it. It has the following features:

FIFO (First In First Out)
Maximum size is fixed; the pointers are stored in a table.
Lockless implementation.
Multi- or single-consumer dequeue.
Multi- or single-producer enqueue.
Bulk dequeue.
Bulk enqueue.

Note: the ring implementation is not preemptable. A lcore must not be interrupted by another task that uses the same ring.

Macro Definition Documentation

#define RING_F_SC_DEQ 0x0002

The default dequeue is "single-consumer".

#define RING_F_SP_ENQ 0x0001

The default enqueue is "single-producer".

#define RTE_RING_NAMESIZE 32

The maximum length of a ring name.

#define RTE_RING_PAUSE_REP_COUNT 0

Yield after pause num of times, no yield if RTE_RING_PAUSE_REP not defined.

#define RTE_RING_QUOT_EXCEED (1 << 31)

Quota exceed for burst ops

#define RTE_RING_SZ_MASK (unsigned)(0x0fffffff)

Ring size mask

Function Documentation

static unsigned rte_ring_count ( const struct rte_ring * r )

inlinestatic

Return the number of entries in a ring.

Parameters

r	A pointer to the ring structure.

Returns: The number of entries in the ring.

struct rte_ring* rte_ring_create	(	const char *	name,
		unsigned	count,
		int	socket_id,
		unsigned	flags
	)

read

Create a new ring named name in memory.

This function uses memzone_reserve() to allocate memory. Then it calls rte_ring_init() to initialize an empty ring.

The new ring size is set to count, which must be a power of two. Water marking is disabled by default. The real usable ring size is count-1 instead of count to differentiate a free ring from an empty ring.

The ring is added in RTE_TAILQ_RING list.

Parameters

name	The name of the ring.
count	The size of the ring (must be a power of 2).
socket_id	The socket_id argument is the socket identifier in case of NUMA. The value can be SOCKET_ID_ANY if there is no NUMA constraint for the reserved zone.
flags	An OR of the following: RING_F_SP_ENQ: If this flag is set, the default behavior when using `rte_ring_enqueue()` or `rte_ring_enqueue_bulk()` is "single-producer". Otherwise, it is "multi-producers". RING_F_SC_DEQ: If this flag is set, the default behavior when using `rte_ring_dequeue()` or `rte_ring_dequeue_bulk()` is "single-consumer". Otherwise, it is "multi-consumers".

Returns

On success, the pointer to the new allocated ring. NULL on error with rte_errno set appropriately. Possible 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 - count provided is not a power of 2
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

static int rte_ring_dequeue	(	struct rte_ring *	r,
		void **	obj_p
	)

inlinestatic

Dequeue one object from a ring.

This function calls the multi-consumers or the single-consumer version depending on the default behaviour that was specified at ring creation time (see flags).

Parameters

r	A pointer to the ring structure.
obj_p	A pointer to a void * pointer (object) that will be filled.

Returns

0: Success, objects dequeued.
-ENOENT: Not enough entries in the ring to dequeue, no object is dequeued.

static int rte_ring_dequeue_bulk	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned	n
	)

inlinestatic

Dequeue several objects from a ring.

This function calls the multi-consumers or the single-consumer version, depending on the default behaviour that was specified at ring creation time (see flags).

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects) that will be filled.
n	The number of objects to dequeue from the ring to the obj_table.

Returns

0: Success; objects dequeued.
-ENOENT: Not enough entries in the ring to dequeue, no object is dequeued.

static unsigned rte_ring_dequeue_burst	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned	n
	)

inlinestatic

Dequeue multiple objects from a ring up to a maximum number.

This function calls the multi-consumers or the single-consumer version, depending on the default behaviour that was specified at ring creation time (see flags).

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects) that will be filled.
n	The number of objects to dequeue from the ring to the obj_table.

Returns

Number of objects dequeued

void rte_ring_dump	(	FILE *	f,
		const struct rte_ring *	r
	)

Dump the status of the ring to the console.

Parameters

f	A pointer to a file for output
r	A pointer to the ring structure.

static int rte_ring_empty ( const struct rte_ring * r )

inlinestatic

Test if a ring is empty.

Parameters

r	A pointer to the ring structure.

Returns

1: The ring is empty.
0: The ring is not empty.

static int rte_ring_enqueue	(	struct rte_ring *	r,
		void *	obj
	)

inlinestatic

Enqueue one object on a ring.

This function calls the multi-producer or the single-producer version, depending on the default behaviour that was specified at ring creation time (see flags).

Parameters

r	A pointer to the ring structure.
obj	A pointer to the object to be added.

Returns

0: Success; objects enqueued.
-EDQUOT: Quota exceeded. The objects have been enqueued, but the high water mark is exceeded.
-ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.

static int rte_ring_enqueue_bulk	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned	n
	)

inlinestatic

Enqueue several objects on a ring.

This function calls the multi-producer or the single-producer version depending on the default behavior that was specified at ring creation time (see flags).

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects).
n	The number of objects to add in the ring from the obj_table.

Returns

0: Success; objects enqueued.
-EDQUOT: Quota exceeded. The objects have been enqueued, but the high water mark is exceeded.
-ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.

static unsigned rte_ring_enqueue_burst	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned	n
	)

inlinestatic

Enqueue several objects on a ring.

This function calls the multi-producer or the single-producer version depending on the default behavior that was specified at ring creation time (see flags).

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects).
n	The number of objects to add in the ring from the obj_table.

Returns

n: Actual number of objects enqueued.

static unsigned rte_ring_free_count ( const struct rte_ring * r )

inlinestatic

Return the number of free entries in a ring.

Parameters

r	A pointer to the ring structure.

Returns: The number of free entries in the ring.

static int rte_ring_full ( const struct rte_ring * r )

inlinestatic

Test if a ring is full.

Parameters

r	A pointer to the ring structure.

Returns

1: The ring is full.
0: The ring is not full.

ssize_t rte_ring_get_memsize ( unsigned count )

Calculate the memory size needed for a ring

This function returns the number of bytes needed for a ring, given the number of elements in it. This value is the sum of the size of the structure rte_ring and the size of the memory needed by the objects pointers. The value is aligned to a cache line size.

Parameters

count The number of elements in the ring (must be a power of 2).

Returns

The memory size needed for the ring on success.
-EINVAL if count is not a power of 2.

int rte_ring_init	(	struct rte_ring *	r,
		const char *	name,
		unsigned	count,
		unsigned	flags
	)

Initialize a ring structure.

Initialize a ring structure in memory pointed by "r". The size of the memory area must be large enough to store the ring structure and the object table. It is advised to use rte_ring_get_memsize() to get the appropriate size.

The ring size is set to count, which must be a power of two. Water marking is disabled by default. The real usable ring size is count-1 instead of count to differentiate a free ring from an empty ring.

The ring is not added in RTE_TAILQ_RING global list. Indeed, the memory given by the caller may not be shareable among dpdk processes.

Parameters

r	The pointer to the ring structure followed by the objects table.
name	The name of the ring.
count	The number of elements in the ring (must be a power of 2).
flags	An OR of the following: RING_F_SP_ENQ: If this flag is set, the default behavior when using `rte_ring_enqueue()` or `rte_ring_enqueue_bulk()` is "single-producer". Otherwise, it is "multi-producers". RING_F_SC_DEQ: If this flag is set, the default behavior when using `rte_ring_dequeue()` or `rte_ring_dequeue_bulk()` is "single-consumer". Otherwise, it is "multi-consumers".

Returns: 0 on success, or a negative value on error.

void rte_ring_list_dump ( FILE * f )

Dump the status of all rings on the console

Parameters

f	A pointer to a file for output

struct rte_ring* rte_ring_lookup ( const char * name )

read

Search a ring from its name

Parameters

name	The name of the ring.

Returns

The pointer to the ring matching the name, or NULL if not found, with rte_errno set appropriately. Possible rte_errno values include:

ENOENT - required entry not available to return.

static int rte_ring_mc_dequeue	(	struct rte_ring *	r,
		void **	obj_p
	)

inlinestatic

Dequeue one object from a ring (multi-consumers safe).

This function uses a "compare and set" instruction to move the consumer index atomically.

Parameters

r	A pointer to the ring structure.
obj_p	A pointer to a void * pointer (object) that will be filled.

Returns

0: Success; objects dequeued.
-ENOENT: Not enough entries in the ring to dequeue; no object is dequeued.

static int rte_ring_mc_dequeue_bulk	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned	n
	)

inlinestatic

Dequeue several objects from a ring (multi-consumers safe).

This function uses a "compare and set" instruction to move the consumer index atomically.

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects) that will be filled.
n	The number of objects to dequeue from the ring to the obj_table.

Returns

0: Success; objects dequeued.
-ENOENT: Not enough entries in the ring to dequeue; no object is dequeued.

static unsigned rte_ring_mc_dequeue_burst	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned	n
	)

inlinestatic

Dequeue several objects from a ring (multi-consumers safe). When the request objects are more than the available objects, only dequeue the actual number of objects

This function uses a "compare and set" instruction to move the consumer index atomically.

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects) that will be filled.
n	The number of objects to dequeue from the ring to the obj_table.

Returns

n: Actual number of objects dequeued, 0 if ring is empty

static int rte_ring_mp_enqueue	(	struct rte_ring *	r,
		void *	obj
	)

inlinestatic

Enqueue one object on a ring (multi-producers safe).

This function uses a "compare and set" instruction to move the producer index atomically.

Parameters

r	A pointer to the ring structure.
obj	A pointer to the object to be added.

Returns

0: Success; objects enqueued.
-EDQUOT: Quota exceeded. The objects have been enqueued, but the high water mark is exceeded.
-ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.

static int rte_ring_mp_enqueue_bulk	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned	n
	)

inlinestatic

Enqueue several objects on the ring (multi-producers safe).

This function uses a "compare and set" instruction to move the producer index atomically.

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects).
n	The number of objects to add in the ring from the obj_table.

Returns

0: Success; objects enqueue.
-EDQUOT: Quota exceeded. The objects have been enqueued, but the high water mark is exceeded.
-ENOBUFS: Not enough room in the ring to enqueue, no object is enqueued.

static unsigned rte_ring_mp_enqueue_burst	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned	n
	)

inlinestatic

Enqueue several objects on the ring (multi-producers safe).

This function uses a "compare and set" instruction to move the producer index atomically.

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects).
n	The number of objects to add in the ring from the obj_table.

Returns

n: Actual number of objects enqueued.

static int rte_ring_sc_dequeue	(	struct rte_ring *	r,
		void **	obj_p
	)

inlinestatic

Dequeue one object from a ring (NOT multi-consumers safe).

Parameters

r	A pointer to the ring structure.
obj_p	A pointer to a void * pointer (object) that will be filled.

Returns

0: Success; objects dequeued.
-ENOENT: Not enough entries in the ring to dequeue, no object is dequeued.

static int rte_ring_sc_dequeue_bulk	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned	n
	)

inlinestatic

Dequeue several objects from a ring (NOT multi-consumers safe).

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects) that will be filled.
n	The number of objects to dequeue from the ring to the obj_table, must be strictly positive.

Returns

0: Success; objects dequeued.
-ENOENT: Not enough entries in the ring to dequeue; no object is dequeued.

static unsigned rte_ring_sc_dequeue_burst	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned	n
	)

inlinestatic

Dequeue several objects from a ring (NOT multi-consumers safe).When the request objects are more than the available objects, only dequeue the actual number of objects

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects) that will be filled.
n	The number of objects to dequeue from the ring to the obj_table.

Returns

n: Actual number of objects dequeued, 0 if ring is empty

int rte_ring_set_water_mark	(	struct rte_ring *	r,
		unsigned	count
	)

Change the high water mark.

If count is 0, water marking is disabled. Otherwise, it is set to the count value. The count value must be greater than 0 and less than the ring size.

This function can be called at any time (not necessarily at initialization).

Parameters

r	A pointer to the ring structure.
count	The new water mark value.

Returns

0: Success; water mark changed.
-EINVAL: Invalid water mark value.

static int rte_ring_sp_enqueue	(	struct rte_ring *	r,
		void *	obj
	)

inlinestatic

Enqueue one object on a ring (NOT multi-producers safe).

Parameters

r	A pointer to the ring structure.
obj	A pointer to the object to be added.

Returns

0: Success; objects enqueued.
-EDQUOT: Quota exceeded. The objects have been enqueued, but the high water mark is exceeded.
-ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.

static int rte_ring_sp_enqueue_bulk	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned	n
	)

inlinestatic

Enqueue several objects on a ring (NOT multi-producers safe).

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects).
n	The number of objects to add in the ring from the obj_table.

Returns

0: Success; objects enqueued.
-EDQUOT: Quota exceeded. The objects have been enqueued, but the high water mark is exceeded.
-ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.

static unsigned rte_ring_sp_enqueue_burst	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned	n
	)

inlinestatic

Enqueue several objects on a ring (NOT multi-producers safe).

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of void * pointers (objects).
n	The number of objects to add in the ring from the obj_table.

Returns

n: Actual number of objects enqueued.

Data Structures

Macros

Functions

Detailed Description

Macro Definition Documentation

Function Documentation