From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755840AbaA1TZW (ORCPT ); Tue, 28 Jan 2014 14:25:22 -0500 Received: from terminus.zytor.com ([198.137.202.10]:34368 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755349AbaA1TZT (ORCPT ); Tue, 28 Jan 2014 14:25:19 -0500 Date: Tue, 28 Jan 2014 11:24:37 -0800 From: tip-bot for Rik van Riel Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, riel@redhat.com, chegu_vinod@hp.com, mgorman@suse.de, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, riel@redhat.com, chegu_vinod@hp.com, mgorman@suse.de, tglx@linutronix.de In-Reply-To: <1390860228-21539-8-git-send-email-riel@redhat.com> References: <1390860228-21539-8-git-send-email-riel@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/numa] sched/numa: Do statistics calculation using local variables only Git-Commit-ID: 35664fd41e1c8cc4f0b89f6a51db5af39ba50640 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Tue, 28 Jan 2014 11:24:43 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 35664fd41e1c8cc4f0b89f6a51db5af39ba50640 Gitweb: http://git.kernel.org/tip/35664fd41e1c8cc4f0b89f6a51db5af39ba50640 Author: Rik van Riel AuthorDate: Mon, 27 Jan 2014 17:03:46 -0500 Committer: Ingo Molnar CommitDate: Tue, 28 Jan 2014 15:03:17 +0100 sched/numa: Do statistics calculation using local variables only 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. Signed-off-by: Rik van Riel Acked-by: Mel Gorman Signed-off-by: Peter Zijlstra Cc: Chegu Vinod Link: http://lkml.kernel.org/r/1390860228-21539-8-git-send-email-riel@redhat.com Signed-off-by: Ingo Molnar --- 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 8fc3a82..4c44990 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1513,12 +1513,9 @@ 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; @@ -1532,13 +1529,12 @@ static void task_numa_placement(struct task_struct *p) f_weight = div64_u64(runtime << 16, period + 1); f_weight = (f_weight * p->numa_faults_buffer_cpu[i]) / (total_faults + 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 */