Commit-ID: 679f9858b1769d740d933f5f1ad9dbe3292f26d2
Gitweb: http://git.kernel.org/tip/679f9858b1769d740d933f5f1ad9dbe3292f26d2
Author: Alexander Gordeev <agordeev@xxxxxxxxxx>
AuthorDate: Wed, 3 Jun 2015 08:18:25 +0200
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Wed, 15 Jul 2015 14:45:14 -0700
rcu: Cleanup rcu_init_geometry() code and arithmetics
This update simplifies rcu_init_geometry() code flow
and makes calculation of the total number of rcu_node
structures more easy to read.
The update relies on the fact num_rcu_lvl[] is never
accessed beyond rcu_num_lvls index by the rest of the
code. Therefore, there is no need initialize the whole
num_rcu_lvl[].
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index ad49dbe..37ca8a8 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4082,7 +4082,6 @@ static void __init rcu_init_geometry(void)
{
ulong d;
int i;
- int j;
int rcu_capacity[MAX_RCU_LVLS + 1];
/*
@@ -4135,24 +4134,21 @@ static void __init rcu_init_geometry(void)
if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS])
panic("rcu_init_geometry: rcu_capacity[] is too small");
+ /* Calculate the number of levels in the tree. */
+ for (i = 1; nr_cpu_ids > rcu_capacity[i]; i++) {
+ }
+ rcu_num_lvls = i;
+
/* Calculate the number of rcu_nodes at each level of the tree. */
- for (i = 1; i <= MAX_RCU_LVLS; i++)
- if (nr_cpu_ids <= rcu_capacity[i]) {
- for (j = 0; j <= i; j++) {
- int cap = rcu_capacity[i - j];
- num_rcu_lvl[j] = DIV_ROUND_UP(nr_cpu_ids, cap);
- }
- rcu_num_lvls = i;
- for (j = i + 1; j <= MAX_RCU_LVLS; j++)
- num_rcu_lvl[j] = 0;
- break;
- }
+ for (i = 0; i < rcu_num_lvls; i++) {
+ int cap = rcu_capacity[rcu_num_lvls - i];
+ num_rcu_lvl[i] = DIV_ROUND_UP(nr_cpu_ids, cap);
+ }
/* Calculate the total number of rcu_node structures. */
rcu_num_nodes = 0;
- for (i = 0; i <= MAX_RCU_LVLS; i++)
+ for (i = 0; i < rcu_num_lvls; i++)
rcu_num_nodes += num_rcu_lvl[i];
- rcu_num_nodes -= nr_cpu_ids;
}
/*
--
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