From: Alexander Gordeev <agordeev@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Alexander Gordeev <agordeev@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH 03/10] rcu: Cleanup rcu_init_geometry() code and arithmetics
Date: Mon, 9 Mar 2015 09:34:07 +0100 [thread overview]
Message-ID: <fc326a782e758be53784e992cfaf9d10c458c238.1425889432.git.agordeev@redhat.com> (raw)
In-Reply-To: <cover.1425889432.git.agordeev@redhat.com>
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@linux.vnet.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
---
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 4045163..c7ad0a9 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4008,7 +4008,6 @@ static void __init rcu_init_geometry(void)
{
ulong d;
int i;
- int j;
int rcu_capacity[MAX_RCU_LVLS + 1];
/*
@@ -4059,24 +4058,21 @@ static void __init rcu_init_geometry(void)
return;
}
+ /* Calculate the number of levels in the tree. */
+ for (i = 0; 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;
}
void __init rcu_init(void)
--
1.8.3.1
next prev parent reply other threads:[~2015-03-09 8:36 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-09 8:34 [PATCH 00/10] rcu: Cleanup RCU tree initialization Alexander Gordeev
2015-03-09 8:34 ` [PATCH 01/10] rcu: Panic if RCU tree can not accommodate all CPUs Alexander Gordeev
2015-03-09 8:34 ` [PATCH 02/10] rcu: Remove superfluous local variable in rcu_init_geometry() Alexander Gordeev
2015-03-09 8:34 ` Alexander Gordeev [this message]
2015-03-09 8:34 ` [PATCH 04/10] rcu: Simplify rcu_init_geometry() capacity arithmetics Alexander Gordeev
2015-03-09 8:34 ` [PATCH 05/10] rcu: Limit rcu_state::levelcnt[] to RCU_NUM_LVLS items Alexander Gordeev
2015-03-09 8:34 ` [PATCH 06/10] rcu: Limit rcu_capacity[] size " Alexander Gordeev
2015-03-09 8:34 ` [PATCH 07/10] rcu: Remove unnecessary fields from rcu_state structure Alexander Gordeev
2015-03-09 8:34 ` [PATCH 08/10] rcu: Limit count of static data to the number of RCU levels Alexander Gordeev
2015-03-09 8:34 ` [PATCH 09/10] rcu: Simplify arithmetic to calculate number of RCU nodes Alexander Gordeev
2015-03-09 8:34 ` [PATCH 10/10] rcu: Remove unnecessary grpnum field from rcu_node structure Alexander Gordeev
2015-03-09 9:36 ` [PATCH 00/10] rcu: Cleanup RCU tree initialization Alexander Gordeev
2015-03-09 21:35 ` Paul E. McKenney
2015-03-10 14:33 ` Alexander Gordeev
2015-03-10 14:57 ` Paul E. McKenney
2015-03-09 21:40 ` Paul E. McKenney
2015-03-09 23:39 ` Paul E. McKenney
2015-03-09 23:49 ` Paul E. McKenney
2015-03-10 4:43 ` Paul E. McKenney
2015-03-10 14:39 ` Alexander Gordeev
2015-03-10 14:52 ` Paul E. McKenney
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