linux-kernel - [PATCH 18/63] sched: numa: Slow scan rate if no NUMA hinting faults are being recorded

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1380288468-5551-19-git-send-email-mgorman@suse.de>
Date:	Fri, 27 Sep 2013 14:27:03 +0100
From:	Mel Gorman <mgorman@...e.de>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Rik van Riel <riel@...hat.com>
Cc:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 18/63] sched: numa: Slow scan rate if no NUMA hinting faults are being recorded

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 <mgorman@...e.de>
---
 kernel/sched/fair.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8b71a5e..cdd656c 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 from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/