From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 9 Mar 2012 03:23:33 +0000 (-0500)
Subject: rcuja: Increase granularity
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=e5227865e1f4a428e1e168dc141254a84c219226;p=userspace-rcu.git

rcuja: Increase granularity

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

diff --git a/rcuja/design.txt b/rcuja/design.txt
index 775ec97..947f61a 100644
--- a/rcuja/design.txt
+++ b/rcuja/design.txt
@@ -223,16 +223,16 @@ least-significant bits.
 Types of children:
 
 enum child_type {
-	LINEAR = 0,	/* Type A */
-			/* 32-bit: 1 to 12 children, 32 to 64 bytes */
-			/* 64-bit: 1 to 14 children, 32 to 128 bytes */
-	BITMAP = 1,	/* Type B */
+	RCU_JA_LINEAR = 0,	/* Type A */
+			/* 32-bit: 1 to 12 children, 8 to 64 bytes */
+			/* 64-bit: 1 to 14 children, 16 to 128 bytes */
+	RCU_JA_BITMAP = 1,	/* Type B */
 			/* 32-bit: 13 to 120 children, 128 to 512 bytes */
 			/* 64-bit: 15 to 124 children, 256 to 1024 bytes */
-	PIGEON = 2,	/* Type C */
+	RCU_JA_PIGEON = 2,	/* Type C */
 			/* 32-bit: 121 to 256 children, 1024 bytes */
 			/* 64-bit: 125 to 256 children, 2048 bytes */
-	LEAF   = 3,	/* Leaf node */
+	/* Leaf nodes are implicit from their height in the tree */
 };
 
 If entire pointer is NULL, children is empty.
diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c
index 6dcd9c6..012b874 100644
--- a/rcuja/rcuja.c
+++ b/rcuja/rcuja.c
@@ -20,6 +20,80 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include <stdint.h>
 #include <urcu/rcuja.h>
 #include "rcuja-internal.h"
 
+enum rcu_ja_child_type {
+	RCU_JA_LINEAR = 0,	/* Type A */
+			/* 32-bit: 1 to 12 children, 8 to 64 bytes */
+			/* 64-bit: 1 to 14 children, 16 to 128 bytes */
+	RCU_JA_BITMAP = 1,	/* Type B */
+			/* 32-bit: 13 to 120 children, 128 to 512 bytes */
+			/* 64-bit: 15 to 124 children, 256 to 1024 bytes */
+	RCU_JA_PIGEON = 2,	/* Type C */
+			/* 32-bit: 121 to 256 children, 1024 bytes */
+			/* 64-bit: 125 to 256 children, 2048 bytes */
+	/* Leaf nodes are implicit from their height in the tree */
+};
+
+struct rcu_ja_type_select {
+	enum rcu_ja_child_type type;
+	uint16_t max_nr_child;	/* 1 to 256 */
+	uint16_t node_order;	/* node size is (1 << node_order), in bytes */
+};
+
+/*
+ * Iteration on the array to find the right node size for the number of
+ * children stops when it reaches max_nr_child == 0 (this is the largest
+ * possible node size, which contains 256 children).
+ */
+const struct rcu_ja_type_select ja_select_u32[] = {
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 1, .node_order = 3, },
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 3, .node_order = 4, },
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 6, .node_order = 5, },
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 12, .node_order = 6, },
+
+	{ .type = RCU_JA_BITMAP, .max_nr_child = 24, .node_order = 7, },
+	{ .type = RCU_JA_BITMAP, .max_nr_child = 56, .node_order = 8, },
+	{ .type = RCU_JA_BITMAP, .max_nr_child = 120, .node_order = 9, },
+
+	{ .type = RCU_JA_PIGEON, .max_nr_child = 256, .node_order = 10, },
+};
+
+const struct rcu_ja_type_select ja_select_u64[] = {
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 1, .node_order = 4, },
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 3, .node_order = 5, },
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 7, .node_order = 6, },
+	{ .type = RCU_JA_LINEAR, .max_nr_child = 14, .node_order = 7, },
+
+	{ .type = RCU_JA_BITMAP, .max_nr_child = 28, .node_order = 8, },
+	{ .type = RCU_JA_BITMAP, .max_nr_child = 60, .node_order = 9, },
+	{ .type = RCU_JA_BITMAP, .max_nr_child = 124, .node_order = 10, },
+
+	{ .type = RCU_JA_PIGEON, .max_nr_child = 256, .node_order = 11, },
+};
+
+/*
+ * The rcu_ja_node starts with a byte counting the number of children in
+ * the node. Then, the node-specific data is placed.
+ * TODO: where should we put the mutex for the node ?
+ *  -> mutex could be a 0-value node count.
+ * TODO: where do we keep nr children for pigeon ?
+ */
+struct rcu_ja_node {
+	char data[];
+};
+
+struct rcu_ja_node *create_rcu_ja_node(struct rcu_ja_type_select *sel)
+{
+	return zmalloc(1 << sel->node_order);
+}
+
+void free_rcu_ja_node(struct rcu_ja_node *node)
+{
+	free(node);
+}
+
+
+