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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-04-23 15:52:53 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-07-02 12:33:20 -0700
commitf885b7f2b2de70be266d2cecc476f773a1e2ca5d (patch)
treec4f4d03ca1469f22701b848274034a74c5ae2b04 /kernel/rcutree.h
parentcba6d0d64ee53772b285d0c0c288deefbeaf7775 (diff)
rcu: Control RCU_FANOUT_LEAF from boot-time parameter
Although making RCU_FANOUT_LEAF a kernel configuration parameter rather than a fixed constant makes it easier for people to decrease cache-miss overhead for large systems, it is of little help for people who must run a single pre-built kernel binary. This commit therefore allows the value of RCU_FANOUT_LEAF to be increased (but not decreased!) via a boot-time parameter named rcutree.rcu_fanout_leaf. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.h')
-rw-r--r--kernel/rcutree.h23
1 files changed, 13 insertions, 10 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 19b61ac1079f..780a0195d35a 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -42,28 +42,28 @@
#define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT)
#if NR_CPUS <= RCU_FANOUT_1
-# define NUM_RCU_LVLS 1
+# define RCU_NUM_LVLS 1
# define NUM_RCU_LVL_0 1
# define NUM_RCU_LVL_1 (NR_CPUS)
# define NUM_RCU_LVL_2 0
# define NUM_RCU_LVL_3 0
# define NUM_RCU_LVL_4 0
#elif NR_CPUS <= RCU_FANOUT_2
-# define NUM_RCU_LVLS 2
+# define RCU_NUM_LVLS 2
# define NUM_RCU_LVL_0 1
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
# define NUM_RCU_LVL_2 (NR_CPUS)
# define NUM_RCU_LVL_3 0
# define NUM_RCU_LVL_4 0
#elif NR_CPUS <= RCU_FANOUT_3
-# define NUM_RCU_LVLS 3
+# define RCU_NUM_LVLS 3
# define NUM_RCU_LVL_0 1
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
# define NUM_RCU_LVL_3 (NR_CPUS)
# define NUM_RCU_LVL_4 0
#elif NR_CPUS <= RCU_FANOUT_4
-# define NUM_RCU_LVLS 4
+# define RCU_NUM_LVLS 4
# define NUM_RCU_LVL_0 1
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
@@ -76,6 +76,9 @@
#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4)
#define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
+extern int rcu_num_lvls;
+extern int rcu_num_nodes;
+
/*
* Dynticks per-CPU state.
*/
@@ -206,7 +209,7 @@ struct rcu_node {
*/
#define rcu_for_each_node_breadth_first(rsp, rnp) \
for ((rnp) = &(rsp)->node[0]; \
- (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++)
+ (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
/*
* Do a breadth-first scan of the non-leaf rcu_node structures for the
@@ -215,7 +218,7 @@ struct rcu_node {
*/
#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
for ((rnp) = &(rsp)->node[0]; \
- (rnp) < (rsp)->level[NUM_RCU_LVLS - 1]; (rnp)++)
+ (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
/*
* Scan the leaves of the rcu_node hierarchy for the specified rcu_state
@@ -224,8 +227,8 @@ struct rcu_node {
* It is still a leaf node, even if it is also the root node.
*/
#define rcu_for_each_leaf_node(rsp, rnp) \
- for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \
- (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++)
+ for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
+ (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
/* Index values for nxttail array in struct rcu_data. */
#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
@@ -357,9 +360,9 @@ do { \
*/
struct rcu_state {
struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
- struct rcu_node *level[NUM_RCU_LVLS]; /* Hierarchy levels. */
+ struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
- u8 levelspread[NUM_RCU_LVLS]; /* kids/node in each level. */
+ u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
/* The following fields are guarded by the root rcu_node's lock. */