#include <rte_ring_rts_c11_mem.h>

Functions
static __rte_experimental __rte_always_inline unsigned int	rte_ring_mp_rts_enqueue_bulk_elem (struct rte_ring r, const void obj_table, unsigned int esize, unsigned int n, unsigned int *free_space)

static __rte_experimental __rte_always_inline unsigned int	rte_ring_mc_rts_dequeue_bulk_elem (struct rte_ring r, void obj_table, unsigned int esize, unsigned int n, unsigned int *available)

static __rte_experimental __rte_always_inline unsigned	rte_ring_mp_rts_enqueue_burst_elem (struct rte_ring r, const void obj_table, unsigned int esize, unsigned int n, unsigned int *free_space)

static __rte_experimental __rte_always_inline unsigned	rte_ring_mc_rts_dequeue_burst_elem (struct rte_ring r, void obj_table, unsigned int esize, unsigned int n, unsigned int *available)

static __rte_experimental __rte_always_inline unsigned int	rte_ring_mp_rts_enqueue_bulk (struct rte_ring r, void const obj_table, unsigned int n, unsigned int free_space)

static __rte_experimental __rte_always_inline unsigned int	rte_ring_mc_rts_dequeue_bulk (struct rte_ring r, void obj_table, unsigned int n, unsigned int available)

static __rte_experimental __rte_always_inline unsigned	rte_ring_mp_rts_enqueue_burst (struct rte_ring r, void const obj_table, unsigned int n, unsigned int free_space)

static __rte_experimental __rte_always_inline unsigned	rte_ring_mc_rts_dequeue_burst (struct rte_ring r, void obj_table, unsigned int n, unsigned int available)

static __rte_experimental uint32_t	rte_ring_get_prod_htd_max (const struct rte_ring *r)

static __rte_experimental int	rte_ring_set_prod_htd_max (struct rte_ring *r, uint32_t v)

static __rte_experimental uint32_t	rte_ring_get_cons_htd_max (const struct rte_ring *r)

static __rte_experimental int	rte_ring_set_cons_htd_max (struct rte_ring *r, uint32_t v)

Detailed Description

EXPERIMENTAL: this API may change without prior notice It is not recommended to include this file directly. Please include <rte_ring.h> instead.

Contains functions for Relaxed Tail Sync (RTS) ring mode. The main idea remains the same as for our original MP/MC synchronization mechanism. The main difference is that tail value is increased not by every thread that finished enqueue/dequeue, but only by the current last one doing enqueue/dequeue. That allows threads to skip spinning on tail value, leaving actual tail value change to last thread at a given instance. RTS requires 2 64-bit CAS for each enqueue(/dequeue) operation: one for head update, second for tail update. As a gain it allows thread to avoid spinning/waiting on tail value. In comparison original MP/MC algorithm requires one 32-bit CAS for head update and waiting/spinning on tail value.

Brief outline:

introduce update counter (cnt) for both head and tail.
increment head.cnt for each head.value update
write head.value and head.cnt atomically (64-bit CAS)
move tail.value ahead only when tail.cnt + 1 == head.cnt (indicating that this is the last thread updating the tail)
increment tail.cnt when each enqueue/dequeue op finishes (no matter if tail.value going to change or not)
write tail.value and tail.cnt atomically (64-bit CAS)

To avoid producer/consumer starvation:

limit max allowed distance between head and tail value (HTD_MAX). I.E. thread is allowed to proceed with changing head.value, only when: head.value - tail.value <= HTD_MAX HTD_MAX is an optional parameter. With HTD_MAX == 0 we'll have fully serialized ring - i.e. only one thread at a time will be able to enqueue/dequeue to/from the ring. With HTD_MAX >= ring.capacity - no limitation. By default HTD_MAX == ring.capacity / 8.

Definition in file rte_ring_rts.h.

Function Documentation

static __rte_experimental __rte_always_inline unsigned int rte_ring_mp_rts_enqueue_bulk_elem	(	struct rte_ring *	r,
		const void *	obj_table,
		unsigned int	esize,
		unsigned int	n,
		unsigned int *	free_space
	)

static

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

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of objects.
esize	The size of ring element, in bytes. It must be a multiple of 4. This must be the same value used while creating the ring. Otherwise the results are undefined.
n	The number of objects to add in the ring from the obj_table.
free_space	if non-NULL, returns the amount of space in the ring after the enqueue operation has finished.

Returns: The number of objects enqueued, either 0 or n

Definition at line 164 of file rte_ring_rts.h.

static __rte_experimental __rte_always_inline unsigned int rte_ring_mc_rts_dequeue_bulk_elem	(	struct rte_ring *	r,
		void *	obj_table,
		unsigned int	esize,
		unsigned int	n,
		unsigned int *	available
	)

static

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

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of objects that will be filled.
esize	The size of ring element, in bytes. It must be a multiple of 4. This must be the same value used while creating the ring. Otherwise the results are undefined.
n	The number of objects to dequeue from the ring to the obj_table.
available	If non-NULL, returns the number of remaining ring entries after the dequeue has finished.

Returns: The number of objects dequeued, either 0 or n

Definition at line 192 of file rte_ring_rts.h.

static __rte_experimental __rte_always_inline unsigned rte_ring_mp_rts_enqueue_burst_elem	(	struct rte_ring *	r,
		const void *	obj_table,
		unsigned int	esize,
		unsigned int	n,
		unsigned int *	free_space
	)

static

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

Parameters

r	A pointer to the ring structure.
obj_table	A pointer to a table of objects.
esize	The size of ring element, in bytes. It must be a multiple of 4. This must be the same value used while creating the ring. Otherwise the results are undefined.
n	The number of objects to add in the ring from the obj_table.
free_space	if non-NULL, returns the amount of space in the ring after the enqueue operation has finished.

Returns

n: Actual number of objects enqueued.

Definition at line 220 of file rte_ring_rts.h.

static __rte_experimental __rte_always_inline unsigned rte_ring_mc_rts_dequeue_burst_elem	(	struct rte_ring *	r,
		void *	obj_table,
		unsigned int	esize,
		unsigned int	n,
		unsigned int *	available
	)

static

Dequeue several objects from an RTS ring (multi-consumers safe). When the requested 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 objects that will be filled.
esize	The size of ring element, in bytes. It must be a multiple of 4. This must be the same value used while creating the ring. Otherwise the results are undefined.
n	The number of objects to dequeue from the ring to the obj_table.
available	If non-NULL, returns the number of remaining ring entries after the dequeue has finished.

Returns

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

Definition at line 250 of file rte_ring_rts.h.

static __rte_experimental __rte_always_inline unsigned int rte_ring_mp_rts_enqueue_bulk	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned int	n,
		unsigned int *	free_space
	)

static

Enqueue several objects on the RTS ring (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.
free_space	if non-NULL, returns the amount of space in the ring after the enqueue operation has finished.

Returns: The number of objects enqueued, either 0 or n

Definition at line 274 of file rte_ring_rts.h.

static __rte_experimental __rte_always_inline unsigned int rte_ring_mc_rts_dequeue_bulk	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned int	n,
		unsigned int *	available
	)

static

Dequeue several objects from an RTS ring (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.
available	If non-NULL, returns the number of remaining ring entries after the dequeue has finished.

Returns: The number of objects dequeued, either 0 or n

Definition at line 298 of file rte_ring_rts.h.

static __rte_experimental __rte_always_inline unsigned rte_ring_mp_rts_enqueue_burst	(	struct rte_ring *	r,
		void const	obj_table,
		unsigned int	n,
		unsigned int *	free_space
	)

static

Enqueue several objects on the RTS ring (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.
free_space	if non-NULL, returns the amount of space in the ring after the enqueue operation has finished.

Returns

n: Actual number of objects enqueued.

Definition at line 322 of file rte_ring_rts.h.

static __rte_experimental __rte_always_inline unsigned rte_ring_mc_rts_dequeue_burst	(	struct rte_ring *	r,
		void **	obj_table,
		unsigned int	n,
		unsigned int *	available
	)

static

Dequeue several objects from an RTS ring (multi-consumers safe). When the requested 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.
available	If non-NULL, returns the number of remaining ring entries after the dequeue has finished.

Returns

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

Definition at line 348 of file rte_ring_rts.h.

static __rte_experimental uint32_t rte_ring_get_prod_htd_max ( const struct rte_ring * r )

inlinestatic

Return producer max Head-Tail-Distance (HTD).

Parameters

r	A pointer to the ring structure.

Returns: Producer HTD value, if producer is set in appropriate sync mode, or UINT32_MAX otherwise.

Definition at line 366 of file rte_ring_rts.h.

static __rte_experimental int rte_ring_set_prod_htd_max	(	struct rte_ring *	r,
		uint32_t	v
	)

inlinestatic

Set producer max Head-Tail-Distance (HTD). Note that producer has to use appropriate sync mode (RTS).

Parameters

r	A pointer to the ring structure.
v	new HTD value to setup.

Returns: Zero on success, or negative error code otherwise.

Definition at line 386 of file rte_ring_rts.h.

static __rte_experimental uint32_t rte_ring_get_cons_htd_max ( const struct rte_ring * r )

inlinestatic

Return consumer max Head-Tail-Distance (HTD).

Parameters

r	A pointer to the ring structure.

Returns: Consumer HTD value, if consumer is set in appropriate sync mode, or UINT32_MAX otherwise.

Definition at line 406 of file rte_ring_rts.h.

static __rte_experimental int rte_ring_set_cons_htd_max	(	struct rte_ring *	r,
		uint32_t	v
	)

inlinestatic

Set consumer max Head-Tail-Distance (HTD). Note that consumer has to use appropriate sync mode (RTS).

Parameters

r	A pointer to the ring structure.
v	new HTD value to setup.

Returns: Zero on success, or negative error code otherwise.

Definition at line 426 of file rte_ring_rts.h.

Functions

Detailed Description

Function Documentation