From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx206.postini.com [74.125.245.206]) by kanga.kvack.org (Postfix) with SMTP id 349AE6B006C for ; Tue, 10 Sep 2013 05:32:53 -0400 (EDT) From: Mel Gorman Subject: [PATCH 18/50] sched: numa: Slow scan rate if no NUMA hinting faults are being recorded Date: Tue, 10 Sep 2013 10:31:58 +0100 Message-Id: <1378805550-29949-19-git-send-email-mgorman@suse.de> In-Reply-To: <1378805550-29949-1-git-send-email-mgorman@suse.de> References: <1378805550-29949-1-git-send-email-mgorman@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra , Rik van Riel Cc: Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML , Mel Gorman 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 29ba117..779ebd7 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 -- 1.8.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org