From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755727AbbE2J4S (ORCPT ); Fri, 29 May 2015 05:56:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:26261 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755968AbbE2Jx5 (ORCPT ); Fri, 29 May 2015 05:53:57 -0400 From: Alexander Gordeev To: linux-kernel@vger.kernel.org Cc: Alexander Gordeev , "Paul E. McKenney" , Steven Rostedt Subject: [PATCH v2 3/9] rcu: Cleanup rcu_init_geometry() code and arithmetics Date: Fri, 29 May 2015 11:53:39 +0200 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" Cc: Steven Rostedt 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 6a418be..0de0a34 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4082,7 +4082,6 @@ static void __init rcu_init_geometry(void) { ulong d; int i; - int j; int rcu_capacity[MAX_RCU_LVLS + 1]; /* @@ -4133,24 +4132,21 @@ static void __init rcu_init_geometry(void) return; } + /* Calculate the number of levels in the tree. */ + for (i = 1; 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; } /* -- 1.8.3.1