Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754185AbbELWcN (ORCPT ); Tue, 12 May 2015 18:32:13 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:60639 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934025AbbELWbK (ORCPT ); Tue, 12 May 2015 18:31:10 -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 06/24] rcu: Cleanup rcu_init_geometry() code and arithmetics Date: Tue, 12 May 2015 15:30:36 -0700 Message-Id: <1431469854-3826-6-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: 15051222-0005-0000-0000-00000ABF11FC Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2164 Lines: 73 From: Alexander Gordeev 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" Signed-off-by: Alexander Gordeev Signed-off-by: Paul E. McKenney --- 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 99431ca4d395..d37a7f80ad9c 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4052,7 +4052,6 @@ static void __init rcu_init_geometry(void) { ulong d; int i; - int j; int rcu_capacity[MAX_RCU_LVLS + 1]; /* @@ -4103,24 +4102,21 @@ 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) -- 1.8.1.5 -- 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/