rte_ring.h

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/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   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 Intel Corporation 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
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 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 */

/*
 * Derived from FreeBSD's bufring.h
 *
 **************************************************************************
 *
 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. The name of Kip Macy nor the names of other
 *    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_H_
#define _RTE_RING_H_

#ifdef __cplusplus
extern "C" {
#endif

#include <stdio.h>
#include <stdint.h>
#include <sys/queue.h>
#include <errno.h>
#include <rte_common.h>
#include <rte_memory.h>
#include <rte_lcore.h>
#include <rte_atomic.h>
#include <rte_branch_prediction.h>
#include <rte_memzone.h>

#define RTE_TAILQ_RING_NAME "RTE_RING"

enum rte_ring_queue_behavior {
    RTE_RING_QUEUE_FIXED = 0, /* Enq/Deq a fixed number of items from a ring */
    RTE_RING_QUEUE_VARIABLE   /* Enq/Deq as many items a possible from ring */
};

#ifdef RTE_LIBRTE_RING_DEBUG

struct rte_ring_debug_stats {
    uint64_t enq_success_bulk; 
    uint64_t enq_success_objs; 
    uint64_t enq_quota_bulk;   
    uint64_t enq_quota_objs;   
    uint64_t enq_fail_bulk;    
    uint64_t enq_fail_objs;    
    uint64_t deq_success_bulk; 
    uint64_t deq_success_objs; 
    uint64_t deq_fail_bulk;    
    uint64_t deq_fail_objs;    
} __rte_cache_aligned;
#endif

#define RTE_RING_MZ_PREFIX "RG_"

#define RTE_RING_NAMESIZE (RTE_MEMZONE_NAMESIZE - \
               sizeof(RTE_RING_MZ_PREFIX) + 1)

#ifndef RTE_RING_PAUSE_REP_COUNT
#define RTE_RING_PAUSE_REP_COUNT 0 
#endif

struct rte_memzone; /* forward declaration, so as not to require memzone.h */

struct rte_ring {
    /*
     * Note: this field kept the RTE_MEMZONE_NAMESIZE size due to ABI
     * compatibility requirements, it could be changed to RTE_RING_NAMESIZE
     * next time the ABI changes
     */
    char name[RTE_MEMZONE_NAMESIZE];    
    int flags;                       
    const struct rte_memzone *memzone;
    struct prod {
        uint32_t watermark;      
        uint32_t sp_enqueue;     
        uint32_t size;           
        uint32_t mask;           
        volatile uint32_t head;  
        volatile uint32_t tail;  
    } prod __rte_cache_aligned;

    struct cons {
        uint32_t sc_dequeue;     
        uint32_t size;           
        uint32_t mask;           
        volatile uint32_t head;  
        volatile uint32_t tail;  
#ifdef RTE_RING_SPLIT_PROD_CONS
    } cons __rte_cache_aligned;
#else
    } cons;
#endif

#ifdef RTE_LIBRTE_RING_DEBUG
    struct rte_ring_debug_stats stats[RTE_MAX_LCORE];
#endif

    void *ring[] __rte_cache_aligned;   
};

#define RING_F_SP_ENQ 0x0001 
#define RING_F_SC_DEQ 0x0002 
#define RTE_RING_QUOT_EXCEED (1 << 31)  
#define RTE_RING_SZ_MASK  (unsigned)(0x0fffffff) 
#ifdef RTE_LIBRTE_RING_DEBUG
#define __RING_STAT_ADD(r, name, n) do {                        \
        unsigned __lcore_id = rte_lcore_id();           \
        if (__lcore_id < RTE_MAX_LCORE) {               \
            r->stats[__lcore_id].name##_objs += n;  \
            r->stats[__lcore_id].name##_bulk += 1;  \
        }                                               \
    } while(0)
#else
#define __RING_STAT_ADD(r, name, n) do {} while(0)
#endif

ssize_t rte_ring_get_memsize(unsigned count);

int rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
    unsigned flags);

struct rte_ring *rte_ring_create(const char *name, unsigned count,
                 int socket_id, unsigned flags);
void rte_ring_free(struct rte_ring *r);

int rte_ring_set_water_mark(struct rte_ring *r, unsigned count);

void rte_ring_dump(FILE *f, const struct rte_ring *r);

/* the actual enqueue of pointers on the ring.
 * Placed here since identical code needed in both
 * single and multi producer enqueue functions */
#define ENQUEUE_PTRS() do { \
    const uint32_t size = r->prod.size; \
    uint32_t idx = prod_head & mask; \
    if (likely(idx + n < size)) { \
        for (i = 0; i < (n & ((~(unsigned)0x3))); i+=4, idx+=4) { \
            r->ring[idx] = obj_table[i]; \
            r->ring[idx+1] = obj_table[i+1]; \
            r->ring[idx+2] = obj_table[i+2]; \
            r->ring[idx+3] = obj_table[i+3]; \
        } \
        switch (n & 0x3) { \
            case 3: r->ring[idx++] = obj_table[i++]; \
            case 2: r->ring[idx++] = obj_table[i++]; \
            case 1: r->ring[idx++] = obj_table[i++]; \
        } \
    } else { \
        for (i = 0; idx < size; i++, idx++)\
            r->ring[idx] = obj_table[i]; \
        for (idx = 0; i < n; i++, idx++) \
            r->ring[idx] = obj_table[i]; \
    } \
} while(0)

/* the actual copy of pointers on the ring to obj_table.
 * Placed here since identical code needed in both
 * single and multi consumer dequeue functions */
#define DEQUEUE_PTRS() do { \
    uint32_t idx = cons_head & mask; \
    const uint32_t size = r->cons.size; \
    if (likely(idx + n < size)) { \
        for (i = 0; i < (n & (~(unsigned)0x3)); i+=4, idx+=4) {\
            obj_table[i] = r->ring[idx]; \
            obj_table[i+1] = r->ring[idx+1]; \
            obj_table[i+2] = r->ring[idx+2]; \
            obj_table[i+3] = r->ring[idx+3]; \
        } \
        switch (n & 0x3) { \
            case 3: obj_table[i++] = r->ring[idx++]; \
            case 2: obj_table[i++] = r->ring[idx++]; \
            case 1: obj_table[i++] = r->ring[idx++]; \
        } \
    } else { \
        for (i = 0; idx < size; i++, idx++) \
            obj_table[i] = r->ring[idx]; \
        for (idx = 0; i < n; i++, idx++) \
            obj_table[i] = r->ring[idx]; \
    } \
} while (0)

static inline int __attribute__((always_inline))
__rte_ring_mp_do_enqueue(struct rte_ring *r, void * const *obj_table,
             unsigned n, enum rte_ring_queue_behavior behavior)
{
    uint32_t prod_head, prod_next;
    uint32_t cons_tail, free_entries;
    const unsigned max = n;
    int success;
    unsigned i, rep = 0;
    uint32_t mask = r->prod.mask;
    int ret;

    /* Avoid the unnecessary cmpset operation below, which is also
     * potentially harmful when n equals 0. */
    if (n == 0)
        return 0;

    /* move prod.head atomically */
    do {
        /* Reset n to the initial burst count */
        n = max;

        prod_head = r->prod.head;

        /* add rmb barrier to avoid load/load reorder in weak
         * memory model. It is noop on x86
         */
        rte_smp_rmb();

        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
         * prod_head > cons_tail). So 'free_entries' is always between 0
         * and size(ring)-1. */
        free_entries = (mask + cons_tail - prod_head);

        /* check that we have enough room in ring */
        if (unlikely(n > free_entries)) {
            if (behavior == RTE_RING_QUEUE_FIXED) {
                __RING_STAT_ADD(r, enq_fail, n);
                return -ENOBUFS;
            }
            else {
                /* No free entry available */
                if (unlikely(free_entries == 0)) {
                    __RING_STAT_ADD(r, enq_fail, n);
                    return 0;
                }

                n = free_entries;
            }
        }

        prod_next = prod_head + n;
        success = rte_atomic32_cmpset(&r->prod.head, prod_head,
                          prod_next);
    } while (unlikely(success == 0));

    /* write entries in ring */
    ENQUEUE_PTRS();
    rte_smp_wmb();

    /* if we exceed the watermark */
    if (unlikely(((mask + 1) - free_entries + n) > r->prod.watermark)) {
        ret = (behavior == RTE_RING_QUEUE_FIXED) ? -EDQUOT :
                (int)(n | RTE_RING_QUOT_EXCEED);
        __RING_STAT_ADD(r, enq_quota, n);
    }
    else {
        ret = (behavior == RTE_RING_QUEUE_FIXED) ? 0 : n;
        __RING_STAT_ADD(r, enq_success, n);
    }

    /*
     * If there are other enqueues in progress that preceded us,
     * we need to wait for them to complete
     */
    while (unlikely(r->prod.tail != prod_head)) {
        rte_pause();

        /* Set RTE_RING_PAUSE_REP_COUNT to avoid spin too long waiting
         * for other thread finish. It gives pre-empted thread a chance
         * to proceed and finish with ring dequeue operation. */
        if (RTE_RING_PAUSE_REP_COUNT &&
            ++rep == RTE_RING_PAUSE_REP_COUNT) {
            rep = 0;
            sched_yield();
        }
    }
    r->prod.tail = prod_next;
    return ret;
}

static inline int __attribute__((always_inline))
__rte_ring_sp_do_enqueue(struct rte_ring *r, void * const *obj_table,
             unsigned n, enum rte_ring_queue_behavior behavior)
{
    uint32_t prod_head, cons_tail;
    uint32_t prod_next, free_entries;
    unsigned i;
    uint32_t mask = r->prod.mask;
    int ret;

    prod_head = r->prod.head;
    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
     * prod_head > cons_tail). So 'free_entries' is always between 0
     * and size(ring)-1. */
    free_entries = mask + cons_tail - prod_head;

    /* check that we have enough room in ring */
    if (unlikely(n > free_entries)) {
        if (behavior == RTE_RING_QUEUE_FIXED) {
            __RING_STAT_ADD(r, enq_fail, n);
            return -ENOBUFS;
        }
        else {
            /* No free entry available */
            if (unlikely(free_entries == 0)) {
                __RING_STAT_ADD(r, enq_fail, n);
                return 0;
            }

            n = free_entries;
        }
    }

    prod_next = prod_head + n;
    r->prod.head = prod_next;

    /* write entries in ring */
    ENQUEUE_PTRS();
    rte_smp_wmb();

    /* if we exceed the watermark */
    if (unlikely(((mask + 1) - free_entries + n) > r->prod.watermark)) {
        ret = (behavior == RTE_RING_QUEUE_FIXED) ? -EDQUOT :
            (int)(n | RTE_RING_QUOT_EXCEED);
        __RING_STAT_ADD(r, enq_quota, n);
    }
    else {
        ret = (behavior == RTE_RING_QUEUE_FIXED) ? 0 : n;
        __RING_STAT_ADD(r, enq_success, n);
    }

    r->prod.tail = prod_next;
    return ret;
}

static inline int __attribute__((always_inline))
__rte_ring_mc_do_dequeue(struct rte_ring *r, void **obj_table,
         unsigned n, enum rte_ring_queue_behavior behavior)
{
    uint32_t cons_head, prod_tail;
    uint32_t cons_next, entries;
    const unsigned max = n;
    int success;
    unsigned i, rep = 0;
    uint32_t mask = r->prod.mask;

    /* Avoid the unnecessary cmpset operation below, which is also
     * potentially harmful when n equals 0. */
    if (n == 0)
        return 0;

    /* move cons.head atomically */
    do {
        /* Restore n as it may change every loop */
        n = max;

        cons_head = r->cons.head;

        /* add rmb barrier to avoid load/load reorder in weak
         * memory model. It is noop on x86
         */
        rte_smp_rmb();

        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 - cons_head);

        /* Set the actual entries for dequeue */
        if (n > entries) {
            if (behavior == RTE_RING_QUEUE_FIXED) {
                __RING_STAT_ADD(r, deq_fail, n);
                return -ENOENT;
            }
            else {
                if (unlikely(entries == 0)){
                    __RING_STAT_ADD(r, deq_fail, n);
                    return 0;
                }

                n = entries;
            }
        }

        cons_next = cons_head + n;
        success = rte_atomic32_cmpset(&r->cons.head, cons_head,
                          cons_next);
    } while (unlikely(success == 0));

    /* copy in table */
    DEQUEUE_PTRS();
    rte_smp_rmb();

    /*
     * If there are other dequeues in progress that preceded us,
     * we need to wait for them to complete
     */
    while (unlikely(r->cons.tail != cons_head)) {
        rte_pause();

        /* Set RTE_RING_PAUSE_REP_COUNT to avoid spin too long waiting
         * for other thread finish. It gives pre-empted thread a chance
         * to proceed and finish with ring dequeue operation. */
        if (RTE_RING_PAUSE_REP_COUNT &&
            ++rep == RTE_RING_PAUSE_REP_COUNT) {
            rep = 0;
            sched_yield();
        }
    }
    __RING_STAT_ADD(r, deq_success, n);
    r->cons.tail = cons_next;

    return behavior == RTE_RING_QUEUE_FIXED ? 0 : n;
}

static inline int __attribute__((always_inline))
__rte_ring_sc_do_dequeue(struct rte_ring *r, void **obj_table,
         unsigned n, enum rte_ring_queue_behavior behavior)
{
    uint32_t cons_head, prod_tail;
    uint32_t cons_next, entries;
    unsigned i;
    uint32_t mask = r->prod.mask;

    cons_head = r->cons.head;
    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 - cons_head;

    if (n > entries) {
        if (behavior == RTE_RING_QUEUE_FIXED) {
            __RING_STAT_ADD(r, deq_fail, n);
            return -ENOENT;
        }
        else {
            if (unlikely(entries == 0)){
                __RING_STAT_ADD(r, deq_fail, n);
                return 0;
            }

            n = entries;
        }
    }

    cons_next = cons_head + n;
    r->cons.head = cons_next;

    /* copy in table */
    DEQUEUE_PTRS();
    rte_smp_rmb();

    __RING_STAT_ADD(r, deq_success, n);
    r->cons.tail = cons_next;
    return behavior == RTE_RING_QUEUE_FIXED ? 0 : n;
}

static inline int __attribute__((always_inline))
rte_ring_mp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
             unsigned n)
{
    return __rte_ring_mp_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED);
}

static inline int __attribute__((always_inline))
rte_ring_sp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
             unsigned n)
{
    return __rte_ring_sp_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED);
}

static inline int __attribute__((always_inline))
rte_ring_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
              unsigned n)
{
    if (r->prod.sp_enqueue)
        return rte_ring_sp_enqueue_bulk(r, obj_table, n);
    else
        return rte_ring_mp_enqueue_bulk(r, obj_table, n);
}

static inline int __attribute__((always_inline))
rte_ring_mp_enqueue(struct rte_ring *r, void *obj)
{
    return rte_ring_mp_enqueue_bulk(r, &obj, 1);
}

static inline int __attribute__((always_inline))
rte_ring_sp_enqueue(struct rte_ring *r, void *obj)
{
    return rte_ring_sp_enqueue_bulk(r, &obj, 1);
}

static inline int __attribute__((always_inline))
rte_ring_enqueue(struct rte_ring *r, void *obj)
{
    if (r->prod.sp_enqueue)
        return rte_ring_sp_enqueue(r, obj);
    else
        return rte_ring_mp_enqueue(r, obj);
}

static inline int __attribute__((always_inline))
rte_ring_mc_dequeue_bulk(struct rte_ring *r, void **obj_table, unsigned n)
{
    return __rte_ring_mc_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED);
}

static inline int __attribute__((always_inline))
rte_ring_sc_dequeue_bulk(struct rte_ring *r, void **obj_table, unsigned n)
{
    return __rte_ring_sc_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED);
}

static inline int __attribute__((always_inline))
rte_ring_dequeue_bulk(struct rte_ring *r, void **obj_table, unsigned n)
{
    if (r->cons.sc_dequeue)
        return rte_ring_sc_dequeue_bulk(r, obj_table, n);
    else
        return rte_ring_mc_dequeue_bulk(r, obj_table, n);
}

static inline int __attribute__((always_inline))
rte_ring_mc_dequeue(struct rte_ring *r, void **obj_p)
{
    return rte_ring_mc_dequeue_bulk(r, obj_p, 1);
}

static inline int __attribute__((always_inline))
rte_ring_sc_dequeue(struct rte_ring *r, void **obj_p)
{
    return rte_ring_sc_dequeue_bulk(r, obj_p, 1);
}

static inline int __attribute__((always_inline))
rte_ring_dequeue(struct rte_ring *r, void **obj_p)
{
    if (r->cons.sc_dequeue)
        return rte_ring_sc_dequeue(r, obj_p);
    else
        return rte_ring_mc_dequeue(r, obj_p);
}

static inline int
rte_ring_full(const struct rte_ring *r)
{
    uint32_t prod_tail = r->prod.tail;
    uint32_t cons_tail = r->cons.tail;
    return ((cons_tail - prod_tail - 1) & r->prod.mask) == 0;
}

static inline int
rte_ring_empty(const struct rte_ring *r)
{
    uint32_t prod_tail = r->prod.tail;
    uint32_t cons_tail = r->cons.tail;
    return !!(cons_tail == prod_tail);
}

static inline unsigned
rte_ring_count(const struct rte_ring *r)
{
    uint32_t prod_tail = r->prod.tail;
    uint32_t cons_tail = r->cons.tail;
    return (prod_tail - cons_tail) & r->prod.mask;
}

static inline unsigned
rte_ring_free_count(const struct rte_ring *r)
{
    uint32_t prod_tail = r->prod.tail;
    uint32_t cons_tail = r->cons.tail;
    return (cons_tail - prod_tail - 1) & r->prod.mask;
}

void rte_ring_list_dump(FILE *f);

struct rte_ring *rte_ring_lookup(const char *name);

static inline unsigned __attribute__((always_inline))
rte_ring_mp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
             unsigned n)
{
    return __rte_ring_mp_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE);
}

static inline unsigned __attribute__((always_inline))
rte_ring_sp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
             unsigned n)
{
    return __rte_ring_sp_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE);
}

static inline unsigned __attribute__((always_inline))
rte_ring_enqueue_burst(struct rte_ring *r, void * const *obj_table,
              unsigned n)
{
    if (r->prod.sp_enqueue)
        return rte_ring_sp_enqueue_burst(r, obj_table, n);
    else
        return rte_ring_mp_enqueue_burst(r, obj_table, n);
}

static inline unsigned __attribute__((always_inline))
rte_ring_mc_dequeue_burst(struct rte_ring *r, void **obj_table, unsigned n)
{
    return __rte_ring_mc_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE);
}

static inline unsigned __attribute__((always_inline))
rte_ring_sc_dequeue_burst(struct rte_ring *r, void **obj_table, unsigned n)
{
    return __rte_ring_sc_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE);
}

static inline unsigned __attribute__((always_inline))
rte_ring_dequeue_burst(struct rte_ring *r, void **obj_table, unsigned n)
{
    if (r->cons.sc_dequeue)
        return rte_ring_sc_dequeue_burst(r, obj_table, n);
    else
        return rte_ring_mc_dequeue_burst(r, obj_table, n);
}

#ifdef __cplusplus
}
#endif

#endif /* _RTE_RING_H_ */