This commit adds support for non-blocking (linked list based) stack mempool
handler. The stack uses a 128-bit compare-and-swap instruction, and thus is
limited to x86_64. The 128-bit CAS atomically updates the stack top pointer
and a modification counter, which protects against the ABA problem.
In mempool_perf_autotest the lock-based stack outperforms the non-blocking
handler*, however:
- For applications with preemptible pthreads, a lock-based stack's
worst-case performance (i.e. one thread being preempted while
holding the spinlock) is much worse than the non-blocking stack's.
- Using per-thread mempool caches will largely mitigate the performance
difference.
*Test setup: x86_64 build with default config, dual-socket Xeon E5-2699 v4,
running on isolcpus cores with a tickless scheduler. The lock-based stack's
rate_persec was 1x-3.5x the non-blocking stack's.
Signed-off-by: Gage Eads <gage.e...@intel.com>
---
MAINTAINERS | 4 +
config/common_base | 1 +
drivers/mempool/Makefile | 1 +
drivers/mempool/nb_stack/Makefile | 30 +++++
drivers/mempool/nb_stack/meson.build | 4 +
drivers/mempool/nb_stack/nb_lifo.h | 132 +++++++++++++++++++++
drivers/mempool/nb_stack/rte_mempool_nb_stack.c | 125 +++++++++++++++++++
.../nb_stack/rte_mempool_nb_stack_version.map | 4 +
mk/rte.app.mk | 1 +
9 files changed, 302 insertions(+)
create mode 100644 drivers/mempool/nb_stack/Makefile
create mode 100644 drivers/mempool/nb_stack/meson.build
create mode 100644 drivers/mempool/nb_stack/nb_lifo.h
create mode 100644 drivers/mempool/nb_stack/rte_mempool_nb_stack.c
create mode 100644 drivers/mempool/nb_stack/rte_mempool_nb_stack_version.map
diff --git a/MAINTAINERS b/MAINTAINERS
index 470f36b9c..5519d3323 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -416,6 +416,10 @@ M: Artem V. Andreev <artem.andr...@oktetlabs.ru>
M: Andrew Rybchenko <arybche...@solarflare.com>
F: drivers/mempool/bucket/
+Non-blocking stack memory pool
+M: Gage Eads <gage.e...@intel.com>
+F: drivers/mempool/nb_stack/
+
Bus Drivers
-----------
diff --git a/config/common_base b/config/common_base
index 964a6956e..40ce47312 100644
--- a/config/common_base
+++ b/config/common_base
@@ -728,6 +728,7 @@ CONFIG_RTE_DRIVER_MEMPOOL_BUCKET=y
CONFIG_RTE_DRIVER_MEMPOOL_BUCKET_SIZE_KB=64
CONFIG_RTE_DRIVER_MEMPOOL_RING=y
CONFIG_RTE_DRIVER_MEMPOOL_STACK=y
+CONFIG_RTE_DRIVER_MEMPOOL_NB_STACK=y
#
# Compile PMD for octeontx fpa mempool device
diff --git a/drivers/mempool/Makefile b/drivers/mempool/Makefile
index 28c2e8360..aeae3ac12 100644
--- a/drivers/mempool/Makefile
+++ b/drivers/mempool/Makefile
@@ -13,5 +13,6 @@ endif
DIRS-$(CONFIG_RTE_DRIVER_MEMPOOL_RING) += ring
DIRS-$(CONFIG_RTE_DRIVER_MEMPOOL_STACK) += stack
DIRS-$(CONFIG_RTE_LIBRTE_OCTEONTX_MEMPOOL) += octeontx
+DIRS-$(CONFIG_RTE_DRIVER_MEMPOOL_NB_STACK) += nb_stack
include $(RTE_SDK)/mk/rte.subdir.mk
diff --git a/drivers/mempool/nb_stack/Makefile
b/drivers/mempool/nb_stack/Makefile
new file mode 100644
index 000000000..38b45f4f5
--- /dev/null
+++ b/drivers/mempool/nb_stack/Makefile
@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2019 Intel Corporation
+
+include $(RTE_SDK)/mk/rte.vars.mk
+
+# The non-blocking stack uses a 128-bit compare-and-swap instruction, and thus
+# is limited to x86_64.
+ifeq ($(CONFIG_RTE_ARCH_X86_64),y)
+
+#
+# library name
+#
+LIB = librte_mempool_nb_stack.a
+
+CFLAGS += -O3
+CFLAGS += $(WERROR_FLAGS)
+
+# Headers
+CFLAGS += -I$(RTE_SDK)/lib/librte_mempool
+LDLIBS += -lrte_eal -lrte_mempool
+
+EXPORT_MAP := rte_mempool_nb_stack_version.map
+
+LIBABIVER := 1
+
+SRCS-$(CONFIG_RTE_DRIVER_MEMPOOL_NB_STACK) += rte_mempool_nb_stack.c
+
+endif
+
+include $(RTE_SDK)/mk/rte.lib.mk
diff --git a/drivers/mempool/nb_stack/meson.build
b/drivers/mempool/nb_stack/meson.build
new file mode 100644
index 000000000..66d64a9ba
--- /dev/null
+++ b/drivers/mempool/nb_stack/meson.build
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2019 Intel Corporation
+
+sources = files('rte_mempool_nb_stack.c')
diff --git a/drivers/mempool/nb_stack/nb_lifo.h
b/drivers/mempool/nb_stack/nb_lifo.h
new file mode 100644
index 000000000..701d75e37
--- /dev/null
+++ b/drivers/mempool/nb_stack/nb_lifo.h
@@ -0,0 +1,132 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2019 Intel Corporation
+ */
+
+#ifndef _NB_LIFO_H_
+#define _NB_LIFO_H_
+
+struct nb_lifo_elem {
+ void *data;
+ struct nb_lifo_elem *next;
+};
+
+struct nb_lifo_head {
+ struct nb_lifo_elem *top; /**< Stack top */
+ uint64_t cnt; /**< Modification counter */
+};
+
+struct nb_lifo {
+ volatile struct nb_lifo_head head __rte_aligned(16);
+ rte_atomic64_t len;
+} __rte_cache_aligned;
+
+static __rte_always_inline void
+nb_lifo_init(struct nb_lifo *lifo)
+{
+ memset(lifo, 0, sizeof(*lifo));
+ rte_atomic64_set(&lifo->len, 0);
+}
+
+static __rte_always_inline unsigned int
+nb_lifo_len(struct nb_lifo *lifo)
+{
+ return (unsigned int) rte_atomic64_read(&lifo->len);
+}
+
+static __rte_always_inline void
+nb_lifo_push(struct nb_lifo *lifo,
+ struct nb_lifo_elem *first,
+ struct nb_lifo_elem *last,
+ unsigned int num)
+{
+ while (1) {
+ struct nb_lifo_head old_head, new_head;
+
+ old_head = lifo->head;
+
+ /* Swing the top pointer to the first element in the list and
+ * make the last element point to the old top.
+ */
+ new_head.top = first;
+ new_head.cnt = old_head.cnt + 1;
+
+ last->next = old_head.top;
+
+ if (rte_atomic128_cmpset((volatile uint64_t *) &lifo->head,
+ (uint64_t *)&old_head,
+ (uint64_t *)&new_head))
+ break;
+ }
+
+ rte_atomic64_add(&lifo->len, num);
+}
+
+static __rte_always_inline void
+nb_lifo_push_single(struct nb_lifo *lifo, struct nb_lifo_elem *elem)
+{
+ nb_lifo_push(lifo, elem, elem, 1);
+}
+
+static __rte_always_inline struct nb_lifo_elem *
+nb_lifo_pop(struct nb_lifo *lifo,
+ unsigned int num,
+ void **obj_table,
+ struct nb_lifo_elem **last)
+{
+ struct nb_lifo_head old_head;
+
+ /* Reserve num elements, if available */
+ while (1) {
+ uint64_t len = rte_atomic64_read(&lifo->len);
+
+ /* Does the list contain enough elements? */
+ if (len < num)
+ return NULL;
+
+ if (rte_atomic64_cmpset((volatile uint64_t *)&lifo->len,
+ len, len - num))
+ break;
+ }
+
+ /* Pop num elements */
+ while (1) {
+ struct nb_lifo_head new_head;
+ struct nb_lifo_elem *tmp;
+ unsigned int i;
+
+ old_head = lifo->head;
+
+ tmp = old_head.top;
+
+ /* Traverse the list to find the new head. A next pointer will
+ * either point to another element or NULL; if a thread
+ * encounters a pointer that has already been popped, the CAS
+ * will fail.
+ */
+ for (i = 0; i < num && tmp != NULL; i++) {
+ if (obj_table)
+ obj_table[i] = tmp->data;
+ if (last)
+ *last = tmp;
+ tmp = tmp->next;
+ }
+
+ /* If NULL was encountered, the list was modified while
+ * traversing it. Retry.
+ */
+ if (i != num)
+ continue;
+
+ new_head.top = tmp;
+ new_head.cnt = old_head.cnt + 1;
+
+ if (rte_atomic128_cmpset((volatile uint64_t *) &lifo->head,
+ (uint64_t *)&old_head,
+ (uint64_t *)&new_head))
+ break;
+ }
+
+ return old_head.top;
+}
+
+#endif /* _NB_LIFO_H_ */
diff --git a/drivers/mempool/nb_stack/rte_mempool_nb_stack.c
b/drivers/mempool/nb_stack/rte_mempool_nb_stack.c
new file mode 100644
index 000000000..1b30775f7
--- /dev/null
+++ b/drivers/mempool/nb_stack/rte_mempool_nb_stack.c
@@ -0,0 +1,125 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2019 Intel Corporation
+ */
+
+#include <stdio.h>
+#include <rte_mempool.h>
+#include <rte_malloc.h>
+
+#include "nb_lifo.h"
+
+struct rte_mempool_nb_stack {
+ uint64_t size;
+ struct nb_lifo used_lifo; /**< LIFO containing mempool pointers */
+ struct nb_lifo free_lifo; /**< LIFO containing unused LIFO elements */
+};
+
+static int
+nb_stack_alloc(struct rte_mempool *mp)
+{
+ struct rte_mempool_nb_stack *s;
+ struct nb_lifo_elem *elems;
+ unsigned int n = mp->size;
+ unsigned int size, i;
+
+ size = sizeof(*s) + n * sizeof(struct nb_lifo_elem);
+
+ /* Allocate our local memory structure */
+ s = rte_zmalloc_socket("mempool-nb_stack",
+ size,
+ RTE_CACHE_LINE_SIZE,
+ mp->socket_id);
+ if (s == NULL) {
+ RTE_LOG(ERR, MEMPOOL, "Cannot allocate nb_stack!\n");
+ return -ENOMEM;
+ }
+
+ s->size = n;
+
+ nb_lifo_init(&s->used_lifo);
+ nb_lifo_init(&s->free_lifo);
+
+ elems = (struct nb_lifo_elem *) &s[1];
+ for (i = 0; i < n; i++)
+ nb_lifo_push_single(&s->free_lifo, &elems[i]);
+
+ mp->pool_data = s;
+
+ return 0;
+}
+
+static int
+nb_stack_enqueue(struct rte_mempool *mp, void * const *obj_table,
+ unsigned int n)
+{
+ struct rte_mempool_nb_stack *s = mp->pool_data;
+ struct nb_lifo_elem *first, *last, *tmp;
+ unsigned int i;
+
+ if (unlikely(n == 0))
+ return 0;
+
+ /* Pop n free elements */
+ first = nb_lifo_pop(&s->free_lifo, n, NULL, NULL);
+ if (unlikely(!first))
+ return -ENOBUFS;
+
+ /* Prepare the list elements */
+ tmp = first;
+ for (i = 0; i < n; i++) {
+ tmp->data = obj_table[i];
+ last = tmp;
+ tmp = tmp->next;
+ }
+
+ /* Enqueue them to the used list */
+ nb_lifo_push(&s->used_lifo, first, last, n);
+
+ return 0;
+}
+
+static int
+nb_stack_dequeue(struct rte_mempool *mp, void **obj_table,
+ unsigned int n)
+{
+ struct rte_mempool_nb_stack *s = mp->pool_data;
+ struct nb_lifo_elem *first, *last;
+
+ if (unlikely(n == 0))
+ return 0;
+
+ /* Pop n used elements */
+ first = nb_lifo_pop(&s->used_lifo, n, obj_table, &last);
+ if (unlikely(!first))
+ return -ENOENT;
+
+ /* Enqueue the list elements to the free list */
+ nb_lifo_push(&s->free_lifo, first, last, n);
+
+ return 0;
+}
+
+static unsigned
+nb_stack_get_count(const struct rte_mempool *mp)
+{
+ struct rte_mempool_nb_stack *s = mp->pool_data;
+
+ return nb_lifo_len(&s->used_lifo);
+}
+
+static void
+nb_stack_free(struct rte_mempool *mp)
+{
+ rte_free((void *)(mp->pool_data));
+}
+
+static struct rte_mempool_ops ops_nb_stack = {
+ .name = "nb_stack",
+ .alloc = nb_stack_alloc,
+ .free = nb_stack_free,
+ .enqueue = nb_stack_enqueue,
+ .dequeue = nb_stack_dequeue,
+ .get_count = nb_stack_get_count
+};
+
+MEMPOOL_REGISTER_OPS(ops_nb_stack);
diff --git a/drivers/mempool/nb_stack/rte_mempool_nb_stack_version.map
b/drivers/mempool/nb_stack/rte_mempool_nb_stack_version.map
new file mode 100644
index 000000000..fc8c95e91
--- /dev/null
+++ b/drivers/mempool/nb_stack/rte_mempool_nb_stack_version.map
@@ -0,0 +1,4 @@
+DPDK_19.05 {
+
+ local: *;
+};
diff --git a/mk/rte.app.mk b/mk/rte.app.mk
index 02e8b6f05..0b11d9417 100644
--- a/mk/rte.app.mk
+++ b/mk/rte.app.mk
@@ -133,6 +133,7 @@ ifeq ($(CONFIG_RTE_BUILD_SHARED_LIB),n)
_LDLIBS-$(CONFIG_RTE_DRIVER_MEMPOOL_BUCKET) += -lrte_mempool_bucket
_LDLIBS-$(CONFIG_RTE_DRIVER_MEMPOOL_STACK) += -lrte_mempool_stack
+_LDLIBS-$(CONFIG_RTE_DRIVER_MEMPOOL_NB_STACK) += -lrte_mempool_nb_stack
ifeq ($(CONFIG_RTE_LIBRTE_DPAA_BUS),y)
_LDLIBS-$(CONFIG_RTE_LIBRTE_DPAA_MEMPOOL) += -lrte_mempool_dpaa
endif
--
2.13.6
