From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754863AbaAUWWm (ORCPT ); Tue, 21 Jan 2014 17:22:42 -0500 Received: from shelob.surriel.com ([74.92.59.67]:44382 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754824AbaAUWWk (ORCPT ); Tue, 21 Jan 2014 17:22:40 -0500 From: riel@redhat.com To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, peterz@infradead.org, mgorman@suse.de, mingo@redhat.com, chegu_vinod@hp.com Subject: [PATCH 7/9] numa,sched: do statistics calculation using local variables only Date: Tue, 21 Jan 2014 17:20:09 -0500 Message-Id: <1390342811-11769-8-git-send-email-riel@redhat.com> X-Mailer: git-send-email 1.8.4.2 In-Reply-To: <1390342811-11769-1-git-send-email-riel@redhat.com> References: <1390342811-11769-1-git-send-email-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rik van Riel The current code in task_numa_placement calculates the difference between the old and the new value, but also temporarily stores half of the old value in the per-process variables. The NUMA balancing code looks at those per-process variables, and having other tasks temporarily see halved statistics could lead to unwanted numa migrations. This can be avoided by doing all the math in local variables. This change also simplifies the code a little. Cc: Peter Zijlstra Cc: Mel Gorman Cc: Ingo Molnar Cc: Chegu Vinod Acked-by: Mel Gorman Signed-off-by: Rik van Riel --- kernel/sched/fair.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index bd2100c..f713f3a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1518,12 +1518,9 @@ static void task_numa_placement(struct task_struct *p) long diff, f_diff, f_weight; i = task_faults_idx(nid, priv); - diff = -p->numa_faults_memory[i]; - f_diff = -p->numa_faults_cpu[i]; /* Decay existing window, copy faults since last scan */ - p->numa_faults_memory[i] >>= 1; - p->numa_faults_memory[i] += p->numa_faults_buffer_memory[i]; + diff = p->numa_faults_buffer_memory[i] - p->numa_faults_memory[i] / 2; fault_types[priv] += p->numa_faults_buffer_memory[i]; p->numa_faults_buffer_memory[i] = 0; @@ -1537,13 +1534,12 @@ static void task_numa_placement(struct task_struct *p) f_weight = (16384 * runtime * p->numa_faults_buffer_cpu[i]) / (total_faults * period + 1); - p->numa_faults_cpu[i] >>= 1; - p->numa_faults_cpu[i] += f_weight; + f_diff = f_weight - p->numa_faults_cpu[i] / 2; p->numa_faults_buffer_cpu[i] = 0; + p->numa_faults_memory[i] += diff; + p->numa_faults_cpu[i] += f_diff; faults += p->numa_faults_memory[i]; - diff += p->numa_faults_memory[i]; - f_diff += p->numa_faults_cpu[i]; p->total_numa_faults += diff; if (p->numa_group) { /* safe because we can only change our own group */ -- 1.8.4.2