[dpdk-dev,v2] ring: guarantee ordering of cons/prod loading when doing

Message ID c2ce8774-a1b6-edf6-444e-ee0981df7497@gmail.com
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Commit Message

Jia He Nov. 7, 2017, 8:34 a.m.
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":
+        *available = entries - n;
+    return n;
+}
+
+#endif /* _RTE_RING_GENERIC_H_ */
+

Comments

Jerin Jacob Nov. 7, 2017, 9:57 a.m. | #1
-----Original Message-----
> Date: Tue, 7 Nov 2017 16:34:30 +0800
> From: Jia He <hejianet@gmail.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Cc: dev@dpdk.org, olivier.matz@6wind.com, konstantin.ananyev@intel.com,
>  bruce.richardson@intel.com, jianbo.liu@arm.com, hemant.agrawal@nxp.com,
>  jie2.liu@hxt-semitech.com, bing.zhao@hxt-semitech.com,
>  jia.he@hxt-semitech.com
> Subject: Re: [PATCH v2] ring: guarantee ordering of cons/prod loading when
>  doing
> User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
>  Thunderbird/52.4.0
> 
> 
> 
> 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?

Why?
If you fix the generic version with rte_smp_rmb() then we just need only
one config to differentiate between c11 vs generic. See comments below,

> Thanks for the patience :-)
> 
> see my drafted patch below, the marcro "PREFER":
> + */
> +
> +#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

You can remove PREFER and let the "generic" version has this. For x86,
rte_smp_?mb() it will be NOOP. So no issue.

> +
> +    /*
> +     * 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);

for c11 mem model version, it needs only __atomic_store_n version.

> +#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

Same as above comment.

> +        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))

> +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)
> +{


Duplicate function, No need to replicate on both versions.


> +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

Same as above comment

> +
> +        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

Same as above comment

> +    } 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)
> +{

Duplicate function, No need to replicate on both versions.


> +    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;

adding rte_smp_rmb() no harm here as it is NOOP for x86 and it is
semantically correct too.


> +        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)
> +{

Duplicate function, No need to replicate on both versions.

> +
> +/**
> + * @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;

Same as above comment.

> +        /* 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)
> +{
Duplicate function, No need to replicate on both versions.
>
Jia He Nov. 8, 2017, 2:31 a.m. | #2
Hi Jerin

Thank you,

I mistakenly think x86 doen't need rte_smp_rmb().

Since rte_smp_rmb() only impact x86's compiler optimization, I will 
simplify the codes as your suggestions

Cheers,

Jia


On 11/7/2017 5:57 PM, Jerin Jacob Wrote:
> -----Original Message-----
>> Date: Tue, 7 Nov 2017 16:34:30 +0800
>> From: Jia He <hejianet@gmail.com>
>> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
>> Cc: dev@dpdk.org, olivier.matz@6wind.com, konstantin.ananyev@intel.com,
>>   bruce.richardson@intel.com, jianbo.liu@arm.com, hemant.agrawal@nxp.com,
>>   jie2.liu@hxt-semitech.com, bing.zhao@hxt-semitech.com,
>>   jia.he@hxt-semitech.com
>> Subject: Re: [PATCH v2] ring: guarantee ordering of cons/prod loading when
>>   doing
>> User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
>>   Thunderbird/52.4.0
>>
>>
>>
>> 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?
> Why?
> If you fix the generic version with rte_smp_rmb() then we just need only
> one config to differentiate between c11 vs generic. See comments below,
>
>> Thanks for the patience :-)
>>
>> see my drafted patch below, the marcro "PREFER":
>> + */
>> +
>> +#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
> You can remove PREFER and let the "generic" version has this. For x86,
> rte_smp_?mb() it will be NOOP. So no issue.
>
>> +
>> +    /*
>> +     * 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);
> for c11 mem model version, it needs only __atomic_store_n version.
>
>> +#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
> Same as above comment.
>
>> +        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))
>> +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)
>> +{
>
> Duplicate function, No need to replicate on both versions.
>
>
>> +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
> Same as above comment
>
>> +
>> +        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
> Same as above comment
>
>> +    } 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)
>> +{
> Duplicate function, No need to replicate on both versions.
>
>
>> +    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;
> adding rte_smp_rmb() no harm here as it is NOOP for x86 and it is
> semantically correct too.
>
>
>> +        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)
>> +{
> Duplicate function, No need to replicate on both versions.
>
>> +
>> +/**
>> + * @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;
> Same as above comment.
>
>> +        /* 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)
>> +{
> Duplicate function, No need to replicate on both versions.

Patch

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)