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rcu: Simplify rcu_init_geometry() capacity arithmetics

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Current code suggests that introducing the extra level to
rcu_capacity[] array makes some of the arithmetic easier.
Well, in fact it appears rather confusing and unnecessary.

Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Alexander Gordeev 2015-06-03 08:18:26 +02:00 committed by Paul E. McKenney
parent 679f9858b1
commit 9618138b09
1 changed files with 8 additions and 10 deletions
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18
kernel/rcu/tree.c
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@ -4082,7 +4082,7 @@ static void __init rcu_init_geometry(void)
{
ulong d;
int i;
int rcu_capacity[MAX_RCU_LVLS + 1];
int rcu_capacity[MAX_RCU_LVLS];
/*
* Initialize any unspecified boot parameters.
@ -4119,29 +4119,27 @@ static void __init rcu_init_geometry(void)
/*
* Compute number of nodes that can be handled an rcu_node tree
* with the given number of levels. Setting rcu_capacity[0] makes
* some of the arithmetic easier.
* with the given number of levels.
*/
rcu_capacity[0] = 1;
rcu_capacity[1] = rcu_fanout_leaf;
for (i = 2; i <= MAX_RCU_LVLS; i++)
rcu_capacity[0] = rcu_fanout_leaf;
for (i = 1; i < MAX_RCU_LVLS; i++)
rcu_capacity[i] = rcu_capacity[i - 1] * RCU_FANOUT;
/*
* The tree must be able to accommodate the configured number of CPUs.
* If this limit is exceeded than we have a serious problem elsewhere.
*/
if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS])
if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS - 1])
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++) {
for (i = 0; nr_cpu_ids > rcu_capacity[i]; i++) {
}
rcu_num_lvls = i;
rcu_num_lvls = i + 1;
/* Calculate the number of rcu_nodes at each level of the tree. */
for (i = 0; i < rcu_num_lvls; i++) {
int cap = rcu_capacity[rcu_num_lvls - i];
int cap = rcu_capacity[(rcu_num_lvls - 1) - i];
num_rcu_lvl[i] = DIV_ROUND_UP(nr_cpu_ids, cap);
}