From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753505AbbCIIgH (ORCPT ); Mon, 9 Mar 2015 04:36:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36138 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753283AbbCIIeZ (ORCPT ); Mon, 9 Mar 2015 04:34:25 -0400 From: Alexander Gordeev To: linux-kernel@vger.kernel.org Cc: Alexander Gordeev , "Paul E. McKenney" Subject: [PATCH 03/10] rcu: Cleanup rcu_init_geometry() code and arithmetics Date: Mon, 9 Mar 2015 09:34:07 +0100 Message-Id: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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