From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 5 Jun 2013 21:43:49 +0000 (-0400)
Subject: rcuja: implement ja_node_ptr fast path
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=1cee749c44c680a4834681bc88d95a6b6c2267b1;p=userspace-rcu.git

rcuja: implement ja_node_ptr fast path

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/rcuja/rcuja-internal.h b/rcuja/rcuja-internal.h
index 1a3346b..202f168 100644
--- a/rcuja/rcuja-internal.h
+++ b/rcuja/rcuja-internal.h
@@ -140,11 +140,36 @@ void ja_node_pool_2d_bitsel(struct cds_ja_inode_flag *node, unsigned long *bits)
 	bits[1] = ((unsigned long) node & JA_POOL_1D_MASK) >> JA_TYPE_BITS;
 }
 
-__attribute__((visibility("protected")))
-unsigned long ja_node_type(struct cds_ja_inode_flag *node);
+/* Hardcoded pool indexes for fast path */
+#define RCU_JA_POOL_IDX_5	5
+#define RCU_JA_POOL_IDX_6	6
+static inline
+struct cds_ja_inode *ja_node_ptr(struct cds_ja_inode_flag *node)
+{
+	unsigned long v, type_idx;
+
+	if (!node)
+		return NULL;	/* RCU_JA_NULL */
+	v = (unsigned long) node;
+	type_idx = v & JA_TYPE_MASK;
+
+	switch (type_idx) {
+	case RCU_JA_POOL_IDX_5:
+		v &= ~(JA_POOL_1D_MASK | JA_TYPE_MASK);
+		break;
+	case RCU_JA_POOL_IDX_6:
+		v &= ~(JA_POOL_2D_MASK | JA_POOL_1D_MASK | JA_TYPE_MASK);
+		break;
+	default:
+		/* RCU_JA_LINEAR or RCU_JA_PIGEON */
+		v &= JA_PTR_MASK;
+		break;
+	}
+	return (struct cds_ja_node *) v;
+}
 
 __attribute__((visibility("protected")))
-struct cds_ja_inode *ja_node_ptr(struct cds_ja_inode_flag *node);
+unsigned long ja_node_type(struct cds_ja_inode_flag *node);
 
 __attribute__((visibility("protected")))
 void rcuja_free_all_children(struct cds_ja_shadow_node *shadow_node,
diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c
index 29b7d8b..c609595 100644
--- a/rcuja/rcuja.c
+++ b/rcuja/rcuja.c
@@ -120,7 +120,9 @@ const struct cds_ja_type ja_types[] = {
 	{ .type_class = RCU_JA_LINEAR, .min_child = 10, .max_child = ja_type_4_max_child, .max_linear_child = ja_type_4_max_linear_child, .order = 7, },
 
 	/* Pools may fill sooner than max_child */
+	/* This pool is hardcoded at index 5. See ja_node_ptr(). */
 	{ .type_class = RCU_JA_POOL, .min_child = 20, .max_child = ja_type_5_max_child, .max_linear_child = ja_type_5_max_linear_child, .order = 8, .nr_pool_order = ja_type_5_nr_pool_order, .pool_size_order = 7, },
+	/* This pool is hardcoded at index 6. See ja_node_ptr(). */
 	{ .type_class = RCU_JA_POOL, .min_child = 45, .max_child = ja_type_6_max_child, .max_linear_child = ja_type_6_max_linear_child, .order = 9, .nr_pool_order = ja_type_6_nr_pool_order, .pool_size_order = 7, },
 
 	/*
@@ -168,7 +170,9 @@ const struct cds_ja_type ja_types[] = {
 	{ .type_class = RCU_JA_LINEAR, .min_child = 10, .max_child = ja_type_4_max_child, .max_linear_child = ja_type_4_max_linear_child, .order = 8, },
 
 	/* Pools may fill sooner than max_child. */
+	/* This pool is hardcoded at index 5. See ja_node_ptr(). */
 	{ .type_class = RCU_JA_POOL, .min_child = 22, .max_child = ja_type_5_max_child, .max_linear_child = ja_type_5_max_linear_child, .order = 9, .nr_pool_order = ja_type_5_nr_pool_order, .pool_size_order = 8, },
+	/* This pool is hardcoded at index 6. See ja_node_ptr(). */
 	{ .type_class = RCU_JA_POOL, .min_child = 51, .max_child = ja_type_6_max_child, .max_linear_child = ja_type_6_max_linear_child, .order = 10, .nr_pool_order = ja_type_6_nr_pool_order, .pool_size_order = 8, },
 
 	/*
@@ -261,30 +265,6 @@ unsigned long ja_node_type(struct cds_ja_inode_flag *node)
 	return type;
 }
 
-struct cds_ja_inode *ja_node_ptr(struct cds_ja_inode_flag *node)
-{
-	unsigned long type_index = ja_node_type(node);
-	const struct cds_ja_type *type;
-
-	type = &ja_types[type_index];
-	switch (type->type_class) {
-	case RCU_JA_LINEAR:
-	case RCU_JA_PIGEON:	/* fall-through */
-	case RCU_JA_NULL:	/* fall-through */
-	default:		/* fall-through */
-		return _ja_node_mask_ptr(node);
-	case RCU_JA_POOL:
-		switch (type->nr_pool_order) {
-		case 1:
-			return (struct cds_ja_inode *) (((unsigned long) node) & ~(JA_POOL_1D_MASK | JA_TYPE_MASK));
-		case 2:
-			return (struct cds_ja_inode *) (((unsigned long) node) & ~(JA_POOL_2D_MASK | JA_POOL_1D_MASK | JA_TYPE_MASK));
-		default:
-			assert(0);
-		}
-	}
-}
-
 static
 struct cds_ja_inode *alloc_cds_ja_node(struct cds_ja *ja,
 		const struct cds_ja_type *ja_type)