[dpdk-dev] [PATCH v2] ring: guarantee ordering of cons/prod loading when doing
Jia He
hejianet at gmail.com
Tue Nov 7 09:34:30 CET 2017
On 11/7/2017 12:36 PM, Jerin Jacob Wrote:
> -----Original Message-----
>
> On option could be to change the prototype of update_tail() and make
> compiler accommodate it for zero cost for arm64(Which I think, it it the
> case. But you can check the generated instructions)
> If not, move, __rte_ring_do_dequeue() and __rte_ring_do_enqueue() instead of
> __rte_ring_move_prod_head/__rte_ring_move_cons_head/update_tail()
>
>
> ➜ [master][dpdk.org] $ git diff
> diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
> index 5e9b3b7b4..b32648825 100644
> --- a/lib/librte_ring/rte_ring.h
> +++ b/lib/librte_ring/rte_ring.h
> @@ -358,8 +358,12 @@ void rte_ring_dump(FILE *f, const struct rte_ring
> *r);
>
> static __rte_always_inline void
> update_tail(struct rte_ring_headtail *ht, uint32_t old_val, uint32_t
> new_val,
> - uint32_t single)
> + uint32_t single, const uint32_t enqueue)
> {
> + if (enqueue)
> + rte_smp_wmb();
> + else
> + rte_smp_rmb();
> /*
> * If there are other enqueues/dequeues in progress that
> * preceded us,
> * we need to wait for them to complete
> @@ -470,9 +474,8 @@ __rte_ring_do_enqueue(struct rte_ring *r, void *
> const *obj_table,
> goto end;
>
> ENQUEUE_PTRS(r, &r[1], prod_head, obj_table, n, void *);
> - rte_smp_wmb();
>
> - update_tail(&r->prod, prod_head, prod_next, is_sp);
> + update_tail(&r->prod, prod_head, prod_next, is_sp, 1);
> end:
> if (free_space != NULL)
> *free_space = free_entries - n;
> @@ -575,9 +578,8 @@ __rte_ring_do_dequeue(struct rte_ring *r, void
> **obj_table,
> goto end;
>
> DEQUEUE_PTRS(r, &r[1], cons_head, obj_table, n, void *);
> - rte_smp_rmb();
>
> - update_tail(&r->cons, cons_head, cons_next, is_sc);
> + update_tail(&r->cons, cons_head, cons_next, is_sc, 0);
>
> end:
> if (available != NULL)
>
>
>
Hi Jerin, yes I knew this suggestion in update_tail.
But what I mean is the rte_smp_rmb() in __rte_ring_move_cons_head and
__rte_ring_move_pros_head:
[option 1]
+ *old_head = r->cons.head;
+ rte_smp_rmb();
+ const uint32_t prod_tail = r->prod.tail;
[option 2]
+ *old_head = __atomic_load_n(&r->cons.head,
+ __ATOMIC_ACQUIRE);
+ *old_head = r->cons.head;
ie.I wonder what is the suitable new config name to distinguish the
above 2 options?
Thanks for the patience :-)
see my drafted patch below, the marcro "PREFER":
diff --git a/lib/librte_ring/rte_ring_c11_mem.h
b/lib/librte_ring/rte_ring_c11_mem.h
new file mode 100644
index 0000000..22fe887
--- /dev/null
+++ b/lib/librte_ring/rte_ring_c11_mem.h
@@ -0,0 +1,305 @@
+/*-
+ * BSD LICENSE
+ *
+ * Copyright(c) 2017 hxt-semitech. 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 hxt-semitech 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.
+ */
+
+#ifndef _RTE_RING_C11_MEM_H_
+#define _RTE_RING_C11_MEM_H_
+
+static __rte_always_inline void
+update_tail(struct rte_ring_headtail *ht, uint32_t old_val, uint32_t
new_val,
+ uint32_t single, uint32_t enqueue)
+{
+ /* Don't need wmb/rmb when we prefer to use load_acquire/
+ * store_release barrier */
+#ifndef PREFER
+ if (enqueue)
+ rte_smp_wmb();
+ else
+ rte_smp_rmb();
+#endif
+
+ /*
+ * If there are other enqueues/dequeues in progress that preceded us,
+ * we need to wait for them to complete
+ */
+ if (!single)
+ while (unlikely(ht->tail != old_val))
+ rte_pause();
+
+#ifdef PREFER
+ __atomic_store_n(&ht->tail, new_val, __ATOMIC_RELEASE);
+#else
+ ht->tail = new_val;
+#endif
+}
+
+/**
+ * @internal This function updates the producer head for enqueue
+ *
+ * @param r
+ * A pointer to the ring structure
+ * @param is_sp
+ * Indicates whether multi-producer path is needed or not
+ * @param n
+ * The number of elements we will want to enqueue, i.e. how far
should the
+ * head be moved
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
+ * @param old_head
+ * Returns head value as it was before the move, i.e. where enqueue
starts
+ * @param new_head
+ * Returns the current/new head value i.e. where enqueue finishes
+ * @param free_entries
+ * Returns the amount of free space in the ring BEFORE head was moved
+ * @return
+ * Actual number of objects enqueued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_move_prod_head(struct rte_ring *r, int is_sp,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ uint32_t *old_head, uint32_t *new_head,
+ uint32_t *free_entries)
+{
+ const uint32_t capacity = r->capacity;
+ unsigned int max = n;
+ int success;
+
+ do {
+ /* Reset n to the initial burst count */
+ n = max;
+
+#ifdef PREFER
+ *old_head = __atomic_load_n(&r->prod.head,
+ __ATOMIC_ACQUIRE);
+#else
+ *old_head = r->prod.head;
+ /* prevent reorder of load/load */
+ rte_smp_rmb();
+#endif
+ const uint32_t cons_tail = r->cons.tail;
+ /*
+ * The subtraction is done between two unsigned 32bits value
+ * (the result is always modulo 32 bits even if we have
+ * *old_head > cons_tail). So 'free_entries' is always between 0
+ * and capacity (which is < size).
+ */
+ *free_entries = (capacity + cons_tail - *old_head);
+
+ /* check that we have enough room in ring */
+ if (unlikely(n > *free_entries))
+ n = (behavior == RTE_RING_QUEUE_FIXED) ?
+ 0 : *free_entries;
+
+ if (n == 0)
+ return 0;
+
+ *new_head = *old_head + n;
+ if (is_sp)
+ r->prod.head = *new_head, success = 1;
+ else
+#ifdef PREFER
+ success = arch_rte_atomic32_cmpset(&r->prod.head,
+ old_head, *new_head,
+ 0, __ATOMIC_ACQUIRE,
+ __ATOMIC_RELAXED);
+#else
+ success = rte_atomic32_cmpset(&r->prod.head,
+ *old_head, *new_head);
+#endif
+ } while (unlikely(success == 0));
+ return n;
+}
+
+/**
+ * @internal Enqueue several objects on the ring
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects).
+ * @param n
+ * The number of objects to add in the ring from the obj_table.
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
+ * @param is_sp
+ * Indicates whether to use single producer or multi-producer head update
+ * @param free_space
+ * returns the amount of space after the enqueue operation has finished
+ * @return
+ * Actual number of objects enqueued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_do_enqueue(struct rte_ring *r, void * const *obj_table,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ int is_sp, unsigned int *free_space)
+{
+ uint32_t prod_head, prod_next;
+ uint32_t free_entries;
+
+ n = __rte_ring_move_prod_head(r, is_sp, n, behavior,
+ &prod_head, &prod_next, &free_entries);
+ if (n == 0)
+ goto end;
+
+ ENQUEUE_PTRS(r, &r[1], prod_head, obj_table, n, void *);
+
+ update_tail(&r->prod, prod_head, prod_next, is_sp, 1);
+end:
+ if (free_space != NULL)
+ *free_space = free_entries - n;
+ return n;
+}
+
+/**
+ * @internal This function updates the consumer head for dequeue
+ *
+ * @param r
+ * A pointer to the ring structure
+ * @param is_sc
+ * Indicates whether multi-consumer path is needed or not
+ * @param n
+ * The number of elements we will want to enqueue, i.e. how far
should the
+ * head be moved
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
+ * @param old_head
+ * Returns head value as it was before the move, i.e. where dequeue
starts
+ * @param new_head
+ * Returns the current/new head value i.e. where dequeue finishes
+ * @param entries
+ * Returns the number of entries in the ring BEFORE head was moved
+ * @return
+ * - Actual number of objects dequeued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_move_cons_head(struct rte_ring *r, int is_sc,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ uint32_t *old_head, uint32_t *new_head,
+ uint32_t *entries)
+{
+ unsigned int max = n;
+ int success;
+
+ /* move cons.head atomically */
+ do {
+ /* Restore n as it may change every loop */
+ n = max;
+#ifdef PREFER
+ *old_head = __atomic_load_n(&r->cons.head,
+ __ATOMIC_ACQUIRE);
+#else
+ *old_head = r->cons.head;
+ /* prevent reorder of load/load */
+ rte_smp_rmb();
+#endif
+
+ const uint32_t prod_tail = r->prod.tail;
+ /* The subtraction is done between two unsigned 32bits value
+ * (the result is always modulo 32 bits even if we have
+ * cons_head > prod_tail). So 'entries' is always between 0
+ * and size(ring)-1. */
+ *entries = (prod_tail - *old_head);
+
+ /* Set the actual entries for dequeue */
+ if (n > *entries)
+ n = (behavior == RTE_RING_QUEUE_FIXED) ? 0 : *entries;
+
+ if (unlikely(n == 0))
+ return 0;
+
+ *new_head = *old_head + n;
+ if (is_sc)
+ r->cons.head = *new_head, success = 1;
+ else
+#ifdef PREFER
+ success = arch_rte_atomic32_cmpset(&r->cons.head,
+ old_head, *new_head,
+ 0, __ATOMIC_ACQUIRE,
+ __ATOMIC_RELAXED);
+#else
+ success = rte_atomic32_cmpset(&r->cons.head, *old_head,
+ *new_head);
+#endif
+ } while (unlikely(success == 0));
+ return n;
+}
+
+/**
+ * @internal Dequeue several objects from the ring
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects).
+ * @param n
+ * The number of objects to pull from the ring.
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
+ * @param is_sc
+ * Indicates whether to use single consumer or multi-consumer head update
+ * @param available
+ * returns the number of remaining ring entries after the dequeue has
finished
+ * @return
+ * - Actual number of objects dequeued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_do_dequeue(struct rte_ring *r, void **obj_table,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ int is_sc, unsigned int *available)
+{
+ uint32_t cons_head, cons_next;
+ uint32_t entries;
+
+ n = __rte_ring_move_cons_head(r, is_sc, n, behavior,
+ &cons_head, &cons_next, &entries);
+ if (n == 0)
+ goto end;
+
+ DEQUEUE_PTRS(r, &r[1], cons_head, obj_table, n, void *);
+
+ update_tail(&r->cons, cons_head, cons_next, is_sc, 0);
+
+end:
+ if (available != NULL)
+ *available = entries - n;
+ return n;
+}
+
+#endif /* _RTE_RING_C11_MEM_H_ */
+
diff --git a/lib/librte_ring/rte_ring_generic.h
b/lib/librte_ring/rte_ring_generic.h
new file mode 100644
index 0000000..0ce6d57
--- /dev/null
+++ b/lib/librte_ring/rte_ring_generic.h
@@ -0,0 +1,268 @@
+/*-
+ * BSD LICENSE
+ *
+ * Copyright(c) 2017 hxt-semitech. 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 hxt-semitech 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.
+ */
+
+#ifndef _RTE_RING_GENERIC_H_
+#define _RTE_RING_GENERIC_H_
+
+static __rte_always_inline void
+update_tail(struct rte_ring_headtail *ht, uint32_t old_val, uint32_t
new_val,
+ uint32_t single, uint32_t enqueue)
+{
+ if (enqueue)
+ rte_smp_wmb();
+ else
+ rte_smp_rmb();
+ /*
+ * If there are other enqueues/dequeues in progress that preceded us,
+ * we need to wait for them to complete
+ */
+ if (!single)
+ while (unlikely(ht->tail != old_val))
+ rte_pause();
+
+ ht->tail = new_val;
+}
+
+/**
+ * @internal This function updates the producer head for enqueue
+ *
+ * @param r
+ * A pointer to the ring structure
+ * @param is_sp
+ * Indicates whether multi-producer path is needed or not
+ * @param n
+ * The number of elements we will want to enqueue, i.e. how far
should the
+ * head be moved
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
+ * @param old_head
+ * Returns head value as it was before the move, i.e. where enqueue
starts
+ * @param new_head
+ * Returns the current/new head value i.e. where enqueue finishes
+ * @param free_entries
+ * Returns the amount of free space in the ring BEFORE head was moved
+ * @return
+ * Actual number of objects enqueued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_move_prod_head(struct rte_ring *r, int is_sp,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ uint32_t *old_head, uint32_t *new_head,
+ uint32_t *free_entries)
+{
+ const uint32_t capacity = r->capacity;
+ unsigned int max = n;
+ int success;
+
+ do {
+ /* Reset n to the initial burst count */
+ n = max;
+
+ *old_head = r->prod.head;
+ const uint32_t cons_tail = r->cons.tail;
+ /*
+ * The subtraction is done between two unsigned 32bits value
+ * (the result is always modulo 32 bits even if we have
+ * *old_head > cons_tail). So 'free_entries' is always between 0
+ * and capacity (which is < size).
+ */
+ *free_entries = (capacity + cons_tail - *old_head);
+
+ /* check that we have enough room in ring */
+ if (unlikely(n > *free_entries))
+ n = (behavior == RTE_RING_QUEUE_FIXED) ?
+ 0 : *free_entries;
+
+ if (n == 0)
+ return 0;
+
+ *new_head = *old_head + n;
+ if (is_sp)
+ r->prod.head = *new_head, success = 1;
+ else
+ success = rte_atomic32_cmpset(&r->prod.head,
+ *old_head, *new_head);
+ } while (unlikely(success == 0));
+ return n;
+}
+
+/**
+ * @internal Enqueue several objects on the ring
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects).
+ * @param n
+ * The number of objects to add in the ring from the obj_table.
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
+ * @param is_sp
+ * Indicates whether to use single producer or multi-producer head update
+ * @param free_space
+ * returns the amount of space after the enqueue operation has finished
+ * @return
+ * Actual number of objects enqueued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_do_enqueue(struct rte_ring *r, void * const *obj_table,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ int is_sp, unsigned int *free_space)
+{
+ uint32_t prod_head, prod_next;
+ uint32_t free_entries;
+
+ n = __rte_ring_move_prod_head(r, is_sp, n, behavior,
+ &prod_head, &prod_next, &free_entries);
+ if (n == 0)
+ goto end;
+
+ ENQUEUE_PTRS(r, &r[1], prod_head, obj_table, n, void *);
+
+ update_tail(&r->prod, prod_head, prod_next, is_sp, 1);
+end:
+ if (free_space != NULL)
+ *free_space = free_entries - n;
+ return n;
+}
+
+/**
+ * @internal This function updates the consumer head for dequeue
+ *
+ * @param r
+ * A pointer to the ring structure
+ * @param is_sc
+ * Indicates whether multi-consumer path is needed or not
+ * @param n
+ * The number of elements we will want to enqueue, i.e. how far
should the
+ * head be moved
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
+ * @param old_head
+ * Returns head value as it was before the move, i.e. where dequeue
starts
+ * @param new_head
+ * Returns the current/new head value i.e. where dequeue finishes
+ * @param entries
+ * Returns the number of entries in the ring BEFORE head was moved
+ * @return
+ * - Actual number of objects dequeued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_move_cons_head(struct rte_ring *r, int is_sc,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ uint32_t *old_head, uint32_t *new_head,
+ uint32_t *entries)
+{
+ unsigned int max = n;
+ int success;
+
+ /* move cons.head atomically */
+ do {
+ /* Restore n as it may change every loop */
+ n = max;
+
+ *old_head = r->cons.head;
+ const uint32_t prod_tail = r->prod.tail;
+ /* The subtraction is done between two unsigned 32bits value
+ * (the result is always modulo 32 bits even if we have
+ * cons_head > prod_tail). So 'entries' is always between 0
+ * and size(ring)-1. */
+ *entries = (prod_tail - *old_head);
+
+ /* Set the actual entries for dequeue */
+ if (n > *entries)
+ n = (behavior == RTE_RING_QUEUE_FIXED) ? 0 : *entries;
+
+ if (unlikely(n == 0))
+ return 0;
+
+ *new_head = *old_head + n;
+ if (is_sc)
+ r->cons.head = *new_head, success = 1;
+ else
+ success = rte_atomic32_cmpset(&r->cons.head, *old_head,
+ *new_head);
+ } while (unlikely(success == 0));
+ return n;
+}
+
+/**
+ * @internal Dequeue several objects from the ring
+ *
+ * @param r
+ * A pointer to the ring structure.
+ * @param obj_table
+ * A pointer to a table of void * pointers (objects).
+ * @param n
+ * The number of objects to pull from the ring.
+ * @param behavior
+ * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
+ * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
+ * @param is_sc
+ * Indicates whether to use single consumer or multi-consumer head update
+ * @param available
+ * returns the number of remaining ring entries after the dequeue has
finished
+ * @return
+ * - Actual number of objects dequeued.
+ * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
+ */
+static __rte_always_inline unsigned int
+__rte_ring_do_dequeue(struct rte_ring *r, void **obj_table,
+ unsigned int n, enum rte_ring_queue_behavior behavior,
+ int is_sc, unsigned int *available)
+{
+ uint32_t cons_head, cons_next;
+ uint32_t entries;
+
+ n = __rte_ring_move_cons_head(r, is_sc, n, behavior,
+ &cons_head, &cons_next, &entries);
+ if (n == 0)
+ goto end;
+
+ DEQUEUE_PTRS(r, &r[1], cons_head, obj_table, n, void *);
+
+ update_tail(&r->cons, cons_head, cons_next, is_sc, 0);
+
+end:
+ if (available != NULL)
+ *available = entries - n;
+ return n;
+}
+
+#endif /* _RTE_RING_GENERIC_H_ */
+
--
2.7.4
--
Cheers,
Jia
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