linux-kernel - [tip:sched/core] 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: <tip-f307cd1a32fab53012b01749a1f5ba10b0a7243f@git.kernel.org>
Date:	Wed, 9 Oct 2013 10:26:51 -0700
From:	tip-bot for Mel Gorman <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org, hannes@...xchg.org, riel@...hat.com,
	aarcange@...hat.com, srikar@...ux.vnet.ibm.com, mgorman@...e.de,
	tglx@...utronix.de
Subject: [tip:sched/core] sched/numa:
  Slow scan rate if no NUMA hinting faults are being recorded

Commit-ID:  f307cd1a32fab53012b01749a1f5ba10b0a7243f
Gitweb:     http://git.kernel.org/tip/f307cd1a32fab53012b01749a1f5ba10b0a7243f
Author:     Mel Gorman <mgorman@...e.de>
AuthorDate: Mon, 7 Oct 2013 11:28:56 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 9 Oct 2013 12:40:21 +0200

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>
Reviewed-by: Rik van Riel <riel@...hat.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-19-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/fair.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e08d757..c6c3302 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
--
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/