Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754306AbbELWc0 (ORCPT ); Tue, 12 May 2015 18:32:26 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:55167 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933986AbbELWbI (ORCPT ); Tue, 12 May 2015 18:31:08 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, Alexander Gordeev , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 09/24] rcu: Limit rcu_capacity[] size to RCU_NUM_LVLS items Date: Tue, 12 May 2015 15:30:39 -0700 Message-Id: <1431469854-3826-9-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1431469854-3826-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20150512223034.GA1396@linux.vnet.ibm.com> <1431469854-3826-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15051222-0033-0000-0000-0000047DC673 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3158 Lines: 90 From: Alexander Gordeev 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" Signed-off-by: Alexander Gordeev Signed-off-by: Paul E. McKenney --- 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 2473a60161a3..69c957ea3723 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3968,19 +3968,19 @@ 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 false positive about array index out of range. */ if (rcu_num_lvls <= 0 || rcu_num_lvls > RCU_NUM_LVLS) @@ -4052,7 +4052,7 @@ 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. @@ -4079,7 +4079,7 @@ 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; /* @@ -4092,7 +4092,7 @@ 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 7194efd3e1d3..8c0a27861d2f 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) -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/