From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752100AbaGVGWc (ORCPT ); Tue, 22 Jul 2014 02:22:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63317 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751595AbaGVGWb (ORCPT ); Tue, 22 Jul 2014 02:22:31 -0400 Date: Tue, 22 Jul 2014 02:21:21 -0400 From: Rik van Riel To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, Kirill Tkhai , Tim Chen , Nicolas Pitre , mingo@kernel.org, pjt@google.com Subject: [PATCH] sched: update last_balance only when actually balanced Message-ID: <20140722022121.4589c63b@annuminas.surriel.com> Organization: Red Hat, Inc. MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently rebalance_domains will happily update sd->last_balance even if should_we_balance() decides that this CPU should not do any load balancing for the sd. This can prevent the CPU that should load balance for the sd from doing load balancing, which can delay active balancing essentially forever. The solution is to only update sd->last_balance when load_balance() actually did something. Signed-off-by: Rik van Riel --- kernel/sched/fair.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 45943b2..4f7fee2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7187,7 +7187,9 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) */ idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; } - sd->last_balance = jiffies; + /* Only update if we actually balanced. */ + if (continue_balancing) + sd->last_balance = jiffies; interval = get_sd_balance_interval(sd, idle != CPU_IDLE); } if (need_serialize)