ceph/src/seastar/dpdk/lib/librte_eventdev/rte_event_ring.h

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2016-2017 Intel Corporation
   3  */
   4
   5 /**
   6  * @file
   7  * RTE Event Ring
   8  *
   9  * This provides a ring implementation for passing rte_event structures
  10  * from one core to another.
  11  */
  12
  13 #ifndef _RTE_EVENT_RING_
  14 #define _RTE_EVENT_RING_
  15
  16 #include <stdint.h>
  17
  18 #include <rte_common.h>
  19 #include <rte_memory.h>
  20 #include <rte_malloc.h>
  21 #include <rte_ring.h>
  22 #include "rte_eventdev.h"
  23
  24 #define RTE_TAILQ_EVENT_RING_NAME "RTE_EVENT_RING"
  25
  26 /**
  27  * Generic ring structure for passing rte_event objects from core to core.
  28  *
  29  * Based on the primitives given in the rte_ring library. Designed to be
  30  * used inside software eventdev implementations and by applications
  31  * directly as needed.
  32  */
  33 struct rte_event_ring {
  34         struct rte_ring r;
  35 };
  36
  37 /**
  38  * Returns the number of events in the ring
  39  *
  40  * @param r
  41  *   pointer to the event ring
  42  * @return
  43  *   the number of events in the ring
  44  */
  45 static __rte_always_inline unsigned int
  46 rte_event_ring_count(const struct rte_event_ring *r)
  47 {
  48         return rte_ring_count(&r->r);
  49 }
  50
  51 /**
  52  * Returns the amount of free space in the ring
  53  *
  54  * @param r
  55  *   pointer to the event ring
  56  * @return
  57  *   the number of free slots in the ring, i.e. the number of events that
  58  *   can be successfully enqueued before dequeue must be called
  59  */
  60 static __rte_always_inline unsigned int
  61 rte_event_ring_free_count(const struct rte_event_ring *r)
  62 {
  63         return rte_ring_free_count(&r->r);
  64 }
  65
  66 /**
  67  * Enqueue a set of events onto a ring
  68  *
  69  * Note: this API enqueues by copying the events themselves onto the ring,
  70  * rather than just placing a pointer to each event onto the ring. This
  71  * means that statically-allocated events can safely be enqueued by this
  72  * API.
  73  *
  74  * @param r
  75  *   pointer to the event ring
  76  * @param events
  77  *   pointer to an array of struct rte_event objects
  78  * @param n
  79  *   number of events in the array to enqueue
  80  * @param free_space
  81  *   if non-null, is updated to indicate the amount of free space in the
  82  *   ring once the enqueue has completed.
  83  * @return
  84  *   the number of elements, n', enqueued to the ring, 0 <= n' <= n
  85  */
  86 static __rte_always_inline unsigned int
  87 rte_event_ring_enqueue_burst(struct rte_event_ring *r,
  88                 const struct rte_event *events,
  89                 unsigned int n, uint16_t *free_space)
  90 {
  91         uint32_t prod_head, prod_next;
  92         uint32_t free_entries;
  93
  94         n = __rte_ring_move_prod_head(&r->r, r->r.prod.single, n,
  95                         RTE_RING_QUEUE_VARIABLE,
  96                         &prod_head, &prod_next, &free_entries);
  97         if (n == 0)
  98                 goto end;
  99
 100         ENQUEUE_PTRS(&r->r, &r[1], prod_head, events, n, struct rte_event);
 101
 102         update_tail(&r->r.prod, prod_head, prod_next, r->r.prod.single, 1);
 103 end:
 104         if (free_space != NULL)
 105                 *free_space = free_entries - n;
 106         return n;
 107 }
 108
 109 /**
 110  * Dequeue a set of events from a ring
 111  *
 112  * Note: this API does not work with pointers to events, rather it copies
 113  * the events themselves to the destination ``events`` buffer.
 114  *
 115  * @param r
 116  *   pointer to the event ring
 117  * @param events
 118  *   pointer to an array to hold the struct rte_event objects
 119  * @param n
 120  *   number of events that can be held in the ``events`` array
 121  * @param available
 122  *   if non-null, is updated to indicate the number of events remaining in
 123  *   the ring once the dequeue has completed
 124  * @return
 125  *   the number of elements, n', dequeued from the ring, 0 <= n' <= n
 126  */
 127 static __rte_always_inline unsigned int
 128 rte_event_ring_dequeue_burst(struct rte_event_ring *r,
 129                 struct rte_event *events,
 130                 unsigned int n, uint16_t *available)
 131 {
 132         uint32_t cons_head, cons_next;
 133         uint32_t entries;
 134
 135         n = __rte_ring_move_cons_head(&r->r, r->r.cons.single, n,
 136                         RTE_RING_QUEUE_VARIABLE,
 137                         &cons_head, &cons_next, &entries);
 138         if (n == 0)
 139                 goto end;
 140
 141         DEQUEUE_PTRS(&r->r, &r[1], cons_head, events, n, struct rte_event);
 142
 143         update_tail(&r->r.cons, cons_head, cons_next, r->r.cons.single, 0);
 144
 145 end:
 146         if (available != NULL)
 147                 *available = entries - n;
 148         return n;
 149 }
 150
 151 /*
 152  * Initializes an already-allocated ring structure
 153  *
 154  * @param r
 155  *   pointer to the ring memory to be initialized
 156  * @param name
 157  *   name to be given to the ring
 158  * @param count
 159  *   the number of elements to be stored in the ring. If the flag
 160  *   ``RING_F_EXACT_SZ`` is not set, this must be a power of 2, and the actual
 161  *   usable space in the ring will be ``count - 1`` entries. If the flag
 162  *   ``RING_F_EXACT_SZ`` is set, the this can be any value up to the ring size
 163  *   limit - 1, and the usable space will be exactly that requested.
 164  * @param flags
 165  *   An OR of the following:
 166  *    - RING_F_SP_ENQ: If this flag is set, the default behavior when
 167  *      using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
 168  *      is "single-producer". Otherwise, it is "multi-producers".
 169  *    - RING_F_SC_DEQ: If this flag is set, the default behavior when
 170  *      using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
 171  *      is "single-consumer". Otherwise, it is "multi-consumers".
 172  *    - RING_F_EXACT_SZ: If this flag is set, the ``count`` parameter is to
 173  *      be taken as the exact usable size of the ring, and as such does not
 174  *      need to be a power of 2. The underlying ring memory should be a
 175  *      power-of-2 size greater than the count value.
 176  * @return
 177  *   0 on success, or a negative value on error.
 178  */
 179 int
 180 rte_event_ring_init(struct rte_event_ring *r, const char *name,
 181         unsigned int count, unsigned int flags);
 182
 183 /*
 184  * Create an event ring structure
 185  *
 186  * This function allocates memory and initializes an event ring inside that
 187  * memory.
 188  *
 189  * @param name
 190  *   name to be given to the ring
 191  * @param count
 192  *   the number of elements to be stored in the ring. If the flag
 193  *   ``RING_F_EXACT_SZ`` is not set, this must be a power of 2, and the actual
 194  *   usable space in the ring will be ``count - 1`` entries. If the flag
 195  *   ``RING_F_EXACT_SZ`` is set, the this can be any value up to the ring size
 196  *   limit - 1, and the usable space will be exactly that requested.
 197  * @param socket_id
 198  *   The *socket_id* argument is the socket identifier in case of
 199  *   NUMA. The value can be *SOCKET_ID_ANY* if there is no NUMA
 200  *   constraint for the reserved zone.
 201  * @param flags
 202  *   An OR of the following:
 203  *    - RING_F_SP_ENQ: If this flag is set, the default behavior when
 204  *      using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
 205  *      is "single-producer". Otherwise, it is "multi-producers".
 206  *    - RING_F_SC_DEQ: If this flag is set, the default behavior when
 207  *      using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
 208  *      is "single-consumer". Otherwise, it is "multi-consumers".
 209  *    - RING_F_EXACT_SZ: If this flag is set, the ``count`` parameter is to
 210  *      be taken as the exact usable size of the ring, and as such does not
 211  *      need to be a power of 2. The underlying ring memory should be a
 212  *      power-of-2 size greater than the count value.
 213  * @return
 214  *   On success, the pointer to the new allocated ring. NULL on error with
 215  *    rte_errno set appropriately. Possible errno values include:
 216  *    - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
 217  *    - E_RTE_SECONDARY - function was called from a secondary process instance
 218  *    - EINVAL - count provided is not a power of 2
 219  *    - ENOSPC - the maximum number of memzones has already been allocated
 220  *    - EEXIST - a memzone with the same name already exists
 221  *    - ENOMEM - no appropriate memory area found in which to create memzone
 222  */
 223 struct rte_event_ring *
 224 rte_event_ring_create(const char *name, unsigned int count, int socket_id,
 225                 unsigned int flags);
 226
 227 /**
 228  * Search for an event ring based on its name
 229  *
 230  * @param name
 231  *   The name of the ring.
 232  * @return
 233  *   The pointer to the ring matching the name, or NULL if not found,
 234  *   with rte_errno set appropriately. Possible rte_errno values include:
 235  *    - ENOENT - required entry not available to return.
 236  */
 237 struct rte_event_ring *
 238 rte_event_ring_lookup(const char *name);
 239
 240 /**
 241  * De-allocate all memory used by the ring.
 242  *
 243  * @param r
 244  *   Ring to free
 245  */
 246 void
 247 rte_event_ring_free(struct rte_event_ring *r);
 248
 249 /**
 250  * Return the size of the event ring.
 251  *
 252  * @param r
 253  *   A pointer to the ring structure.
 254  * @return
 255  *   The size of the data store used by the ring.
 256  *   NOTE: this is not the same as the usable space in the ring. To query that
 257  *   use ``rte_ring_get_capacity()``.
 258  */
 259 static inline unsigned int
 260 rte_event_ring_get_size(const struct rte_event_ring *r)
 261 {
 262         return rte_ring_get_size(&r->r);
 263 }
 264
 265 /**
 266  * Return the number of elements which can be stored in the event ring.
 267  *
 268  * @param r
 269  *   A pointer to the ring structure.
 270  * @return
 271  *   The usable size of the ring.
 272  */
 273 static inline unsigned int
 274 rte_event_ring_get_capacity(const struct rte_event_ring *r)
 275 {
 276         return rte_ring_get_capacity(&r->r);
 277 }
 278 #endif