mempool: add stack mempool handler

This is a mempool handler that is useful for pipelining apps, where
the mempool cache doesn't really work - example, where we have one
core doing rx (and alloc), and another core doing Tx (and return).
In such a case, the mempool ring simply cycles through all the mbufs,
resulting in a LLC miss on every mbuf allocated when the number of
mbufs is large. A stack (LIFO) recycles buffers more effectively in
this case.

Signed-off-by: David Hunt <david.hunt@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>

diff --git a/lib/librte_mempool/Makefile b/lib/librte_mempool/Makefile
index a4c089e..057a6ab 100644 (file)
--- a/lib/librte_mempool/Makefile
+++ b/lib/librte_mempool/Makefile
@@ -44,6 +44,7 @@ LIBABIVER := 2
 SRCS-$(CONFIG_RTE_LIBRTE_MEMPOOL) +=  rte_mempool.c
 SRCS-$(CONFIG_RTE_LIBRTE_MEMPOOL) +=  rte_mempool_ops.c
 SRCS-$(CONFIG_RTE_LIBRTE_MEMPOOL) +=  rte_mempool_ring.c
+SRCS-$(CONFIG_RTE_LIBRTE_MEMPOOL) +=  rte_mempool_stack.c
 # install includes
 SYMLINK-$(CONFIG_RTE_LIBRTE_MEMPOOL)-include := rte_mempool.h
 

diff --git a/lib/librte_mempool/rte_mempool_stack.c b/lib/librte_mempool/rte_mempool_stack.c
new file mode 100644 (file)
index 0000000..5fd8af2
--- /dev/null
+++ b/lib/librte_mempool/rte_mempool_stack.c
@@ -0,0 +1,147 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2016 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
+ *   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.
+ */
+
+#include <stdio.h>
+#include <rte_mempool.h>
+#include <rte_malloc.h>
+
+struct rte_mempool_stack {
+       rte_spinlock_t sl;
+
+       uint32_t size;
+       uint32_t len;
+       void *objs[];
+};
+
+static int
+stack_alloc(struct rte_mempool *mp)
+{
+       struct rte_mempool_stack *s;
+       unsigned n = mp->size;
+       int size = sizeof(*s) + (n+16)*sizeof(void *);
+
+       /* Allocate our local memory structure */
+       s = rte_zmalloc_socket("mempool-stack",
+                       size,
+                       RTE_CACHE_LINE_SIZE,
+                       mp->socket_id);
+       if (s == NULL) {
+               RTE_LOG(ERR, MEMPOOL, "Cannot allocate stack!\n");
+               return -ENOMEM;
+       }
+
+       rte_spinlock_init(&s->sl);
+
+       s->size = n;
+       mp->pool_data = s;
+
+       return 0;
+}
+
+static int
+stack_enqueue(struct rte_mempool *mp, void * const *obj_table,
+               unsigned n)
+{
+       struct rte_mempool_stack *s = mp->pool_data;
+       void **cache_objs;
+       unsigned index;
+
+       rte_spinlock_lock(&s->sl);
+       cache_objs = &s->objs[s->len];
+
+       /* Is there sufficient space in the stack ? */
+       if ((s->len + n) > s->size) {
+               rte_spinlock_unlock(&s->sl);
+               return -ENOBUFS;
+       }
+
+       /* Add elements back into the cache */
+       for (index = 0; index < n; ++index, obj_table++)
+               cache_objs[index] = *obj_table;
+
+       s->len += n;
+
+       rte_spinlock_unlock(&s->sl);
+       return 0;
+}
+
+static int
+stack_dequeue(struct rte_mempool *mp, void **obj_table,
+               unsigned n)
+{
+       struct rte_mempool_stack *s = mp->pool_data;
+       void **cache_objs;
+       unsigned index, len;
+
+       rte_spinlock_lock(&s->sl);
+
+       if (unlikely(n > s->len)) {
+               rte_spinlock_unlock(&s->sl);
+               return -ENOENT;
+       }
+
+       cache_objs = s->objs;
+
+       for (index = 0, len = s->len - 1; index < n;
+                       ++index, len--, obj_table++)
+               *obj_table = cache_objs[len];
+
+       s->len -= n;
+       rte_spinlock_unlock(&s->sl);
+       return n;
+}
+
+static unsigned
+stack_get_count(const struct rte_mempool *mp)
+{
+       struct rte_mempool_stack *s = mp->pool_data;
+
+       return s->len;
+}
+
+static void
+stack_free(struct rte_mempool *mp)
+{
+       rte_free((void *)(mp->pool_data));
+}
+
+static struct rte_mempool_ops ops_stack = {
+       .name = "stack",
+       .alloc = stack_alloc,
+       .free = stack_free,
+       .enqueue = stack_enqueue,
+       .dequeue = stack_dequeue,
+       .get_count = stack_get_count
+};
+
+MEMPOOL_REGISTER_OPS(ops_stack);