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 06/10] rcu: Limit rcu_capacity[] size to RCU_NUM_LVLS items
Date: Mon, 9 Mar 2015 09:34:10 +0100 [thread overview]
Message-ID: <f23c9a049f317e5dfdfdafc229f85b5924702a31.1425889432.git.agordeev@redhat.com> (raw)
In-Reply-To: <cover.1425889432.git.agordeev@redhat.com>
Number of items in rcu_capacity[] array is defined by macro
MAX_RCU_LVLS. However, that array is never accessed beyond
RCU_NUM_LVLS index. Therefore, we can limit the array to
RCU_NUM_LVLS items and eliminate MAX_RCU_LVLS. As result,
in most cases the memory is conserved.
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
---
kernel/rcu/tree.c | 12 ++++++------
kernel/rcu/tree.h | 1 -
2 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 98e36c3..dbcec66 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3924,19 +3924,19 @@ static void __init rcu_init_one(struct rcu_state *rsp,
"rcu_node_0",
"rcu_node_1",
"rcu_node_2",
- "rcu_node_3" }; /* Match MAX_RCU_LVLS */
+ "rcu_node_3" };
static const char * const fqs[] = {
"rcu_node_fqs_0",
"rcu_node_fqs_1",
"rcu_node_fqs_2",
- "rcu_node_fqs_3" }; /* Match MAX_RCU_LVLS */
+ "rcu_node_fqs_3" };
static u8 fl_mask = 0x1;
int cpustride = 1;
int i;
int j;
struct rcu_node *rnp;
- BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */
+ BUILD_BUG_ON(RCU_NUM_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */
/* Silence gcc 4.8 warning about array index out of range. */
if (rcu_num_lvls > RCU_NUM_LVLS)
@@ -4008,7 +4008,7 @@ static void __init rcu_init_geometry(void)
{
ulong d;
int i;
- int rcu_capacity[MAX_RCU_LVLS];
+ int rcu_capacity[RCU_NUM_LVLS];
/*
* Initialize any unspecified boot parameters.
@@ -4035,7 +4035,7 @@ static void __init rcu_init_geometry(void)
* with the given number of levels.
*/
rcu_capacity[0] = rcu_fanout_leaf;
- for (i = 1; i < MAX_RCU_LVLS; i++)
+ for (i = 1; i < RCU_NUM_LVLS; i++)
rcu_capacity[i] = rcu_capacity[i - 1] * CONFIG_RCU_FANOUT;
/*
@@ -4048,7 +4048,7 @@ static void __init rcu_init_geometry(void)
* the rcu_node masks. Complain and fall back to the compile-
* time values if these limits are exceeded.
*/
- if (nr_cpu_ids > rcu_capacity[MAX_RCU_LVLS - 1])
+ if (nr_cpu_ids > rcu_capacity[RCU_NUM_LVLS - 1])
panic("rcu_init_geometry: rcu_capacity[] is too small");
else if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF ||
rcu_fanout_leaf > sizeof(unsigned long) * 8) {
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index f358a83..661d2d4 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -35,7 +35,6 @@
* In practice, this did work well going from three levels to four.
* Of course, your mileage may vary.
*/
-#define MAX_RCU_LVLS 4
#define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF)
#define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT)
#define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT)
--
1.8.3.1
next prev parent reply other threads:[~2015-03-09 8:34 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 ` [PATCH 03/10] rcu: Cleanup rcu_init_geometry() code and arithmetics Alexander Gordeev
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 ` Alexander Gordeev [this message]
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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