ring: introduce RTS ring mode

[dpdk.git] / lib / librte_ring / rte_ring.c

diff --git a/lib/librte_ring/rte_ring.c b/lib/librte_ring/rte_ring.c
index fa57339..222eec0 100644 (file)
--- a/lib/librte_ring/rte_ring.c
+++ b/lib/librte_ring/rte_ring.c
@@ -45,6 +45,9 @@ EAL_REGISTER_TAILQ(rte_ring_tailq)
 /* true if x is a power of 2 */
 #define POWEROF2(x) ((((x)-1) & (x)) == 0)
 
+/* by default set head/tail distance as 1/8 of ring capacity */
+#define HTD_MAX_DEF    8
+
 /* return the size of memory occupied by a ring */
 ssize_t
 rte_ring_get_memsize_elem(unsigned int esize, unsigned int count)
@@ -79,11 +82,84 @@ rte_ring_get_memsize(unsigned int count)
        return rte_ring_get_memsize_elem(sizeof(void *), count);
 }
 
+/*
+ * internal helper function to reset prod/cons head-tail values.
+ */
+static void
+reset_headtail(void *p)
+{
+       struct rte_ring_headtail *ht;
+       struct rte_ring_rts_headtail *ht_rts;
+
+       ht = p;
+       ht_rts = p;
+
+       switch (ht->sync_type) {
+       case RTE_RING_SYNC_MT:
+       case RTE_RING_SYNC_ST:
+               ht->head = 0;
+               ht->tail = 0;
+               break;
+       case RTE_RING_SYNC_MT_RTS:
+               ht_rts->head.raw = 0;
+               ht_rts->tail.raw = 0;
+               break;
+       default:
+               /* unknown sync mode */
+               RTE_ASSERT(0);
+       }
+}
+
 void
 rte_ring_reset(struct rte_ring *r)
 {
-       r->prod.head = r->cons.head = 0;
-       r->prod.tail = r->cons.tail = 0;
+       reset_headtail(&r->prod);
+       reset_headtail(&r->cons);
+}
+
+/*
+ * helper function, calculates sync_type values for prod and cons
+ * based on input flags. Returns zero at success or negative
+ * errno value otherwise.
+ */
+static int
+get_sync_type(uint32_t flags, enum rte_ring_sync_type *prod_st,
+       enum rte_ring_sync_type *cons_st)
+{
+       static const uint32_t prod_st_flags =
+               (RING_F_SP_ENQ | RING_F_MP_RTS_ENQ);
+       static const uint32_t cons_st_flags =
+               (RING_F_SC_DEQ | RING_F_MC_RTS_DEQ);
+
+       switch (flags & prod_st_flags) {
+       case 0:
+               *prod_st = RTE_RING_SYNC_MT;
+               break;
+       case RING_F_SP_ENQ:
+               *prod_st = RTE_RING_SYNC_ST;
+               break;
+       case RING_F_MP_RTS_ENQ:
+               *prod_st = RTE_RING_SYNC_MT_RTS;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       switch (flags & cons_st_flags) {
+       case 0:
+               *cons_st = RTE_RING_SYNC_MT;
+               break;
+       case RING_F_SC_DEQ:
+               *cons_st = RTE_RING_SYNC_ST;
+               break;
+       case RING_F_MC_RTS_DEQ:
+               *cons_st = RTE_RING_SYNC_MT_RTS;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       return 0;
 }
 
 int
@@ -100,16 +176,20 @@ rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
        RTE_BUILD_BUG_ON((offsetof(struct rte_ring, prod) &
                          RTE_CACHE_LINE_MASK) != 0);
 
+       RTE_BUILD_BUG_ON(offsetof(struct rte_ring_headtail, sync_type) !=
+               offsetof(struct rte_ring_rts_headtail, sync_type));
+       RTE_BUILD_BUG_ON(offsetof(struct rte_ring_headtail, tail) !=
+               offsetof(struct rte_ring_rts_headtail, tail.val.pos));
+
        /* init the ring structure */
        memset(r, 0, sizeof(*r));
        ret = strlcpy(r->name, name, sizeof(r->name));
        if (ret < 0 || ret >= (int)sizeof(r->name))
                return -ENAMETOOLONG;
        r->flags = flags;
-       r->prod.sync_type = (flags & RING_F_SP_ENQ) ?
-               RTE_RING_SYNC_ST : RTE_RING_SYNC_MT;
-       r->cons.sync_type = (flags & RING_F_SC_DEQ) ?
-               RTE_RING_SYNC_ST : RTE_RING_SYNC_MT;
+       ret = get_sync_type(flags, &r->prod.sync_type, &r->cons.sync_type);
+       if (ret != 0)
+               return ret;
 
        if (flags & RING_F_EXACT_SZ) {
                r->size = rte_align32pow2(count + 1);
@@ -126,8 +206,12 @@ rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
                r->mask = count - 1;
                r->capacity = r->mask;
        }
-       r->prod.head = r->cons.head = 0;
-       r->prod.tail = r->cons.tail = 0;
+
+       /* set default values for head-tail distance */
+       if (flags & RING_F_MP_RTS_ENQ)
+               rte_ring_set_prod_htd_max(r, r->capacity / HTD_MAX_DEF);
+       if (flags & RING_F_MC_RTS_DEQ)
+               rte_ring_set_cons_htd_max(r, r->capacity / HTD_MAX_DEF);
 
        return 0;
 }