Hi Stephen,
Suggesting minor changes to comments on acquire and
release fences..
+/** @name SMP Memory Barrier
+ */
+///@{
+/**
+ * General memory barrier between lcores
+ *
+ * Guarantees that the LOAD and STORE operations that precede the
+ * rte_smp_mb() call are globally visible across the lcores
+ * before the LOAD and STORE operations that follows it.
+ */
+static __rte_always_inline void
+rte_smp_mb(void)
+{
+ rte_atomic_thread_fence(rte_memory_order_seq_cst);
+}
+
+/**
+ * Write memory barrier between lcores
+ *
+ * Guarantees that the STORE operations that precede the
+ * rte_smp_wmb() call are globally visible across the lcores
+ * before the STORE operations that follows it.
+ */
+static __rte_always_inline void
+rte_smp_wmb(void)
+{
+ rte_atomic_thread_fence(rte_memory_order_release);
+}
Release fences order STORE | STORE, and LOAD | STORE.
Therefor, the comment should be "Guarantees that LOAD
and STORE operations that precede the rte_smp_wmb() call
are globally observed before STORE operations that follows it."
+
+/**
+ * Read memory barrier between lcores
+ *
+ * Guarantees that the LOAD operations that precede the
+ * rte_smp_rmb() call are globally visible across the lcores
+ * before the LOAD operations that follows it.
+ */
+static __rte_always_inline void
+rte_smp_rmb(void)
+{
+ rte_atomic_thread_fence(rte_memory_order_acquire);
+}
Acquire fences order LOAD | LOAD and LOAD | STORE.
Thus, the comment should be "Guarantees that the LOAD
operations that precede the rte_smp_rmb() call observe
global state before LOAD and STORE operations that
follows it"
--wathsala
