From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756052Ab3JGKmJ (ORCPT ); Mon, 7 Oct 2013 06:42:09 -0400 Received: from cantor2.suse.de ([195.135.220.15]:39731 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751734Ab3JGK37 (ORCPT ); Mon, 7 Oct 2013 06:29:59 -0400 From: Mel Gorman To: Peter Zijlstra , Rik van Riel Cc: Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML , Mel Gorman Subject: [PATCH 18/63] sched: numa: Slow scan rate if no NUMA hinting faults are being recorded Date: Mon, 7 Oct 2013 11:28:56 +0100 Message-Id: <1381141781-10992-19-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.8.4 In-Reply-To: <1381141781-10992-1-git-send-email-mgorman@suse.de> References: <1381141781-10992-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org NUMA PTE scanning slows if a NUMA hinting fault was trapped and no page was migrated. For long-lived but idle processes there may be no faults but the scan rate will be high and just waste CPU. This patch will slow the scan rate for processes that are not trapping faults. Signed-off-by: Mel Gorman --- kernel/sched/fair.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c0092e5..8cea7a2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1039,6 +1039,18 @@ void task_numa_work(struct callback_head *work) out: /* + * If the whole process was scanned without updates then no NUMA + * hinting faults are being recorded and scan rate should be lower. + */ + if (mm->numa_scan_offset == 0 && !nr_pte_updates) { + p->numa_scan_period = min(p->numa_scan_period_max, + p->numa_scan_period << 1); + + next_scan = now + msecs_to_jiffies(p->numa_scan_period); + mm->numa_next_scan = next_scan; + } + + /* * It is possible to reach the end of the VMA list but the last few * VMAs are not guaranteed to the vma_migratable. If they are not, we * would find the !migratable VMA on the next scan but not reset the -- 1.8.4