linux-kernel - [PATCH 11/50] sched: numa: Continue PTE scanning even if migrate rate limited

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Date:	Tue, 10 Sep 2013 10:31:51 +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 11/50] sched: numa: Continue PTE scanning even if migrate rate limited

From: Peter Zijlstra <peterz@...radead.org>

Avoiding marking PTEs pte_numa because a particular NUMA node is migrate rate
limited sees like a bad idea. Even if this node can't migrate anymore other
nodes might and we want up-to-date information to do balance decisions.
We already rate limit the actual migrations, this should leave enough
bandwidth to allow the non-migrating scanning. I think its important we
keep up-to-date information if we're going to do placement based on it.

Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 kernel/sched/fair.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c93a56e..b5aa546 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -951,14 +951,6 @@ void task_numa_work(struct callback_head *work)
 	 */
 	p->node_stamp += 2 * TICK_NSEC;
 
-	/*
-	 * Do not set pte_numa if the current running node is rate-limited.
-	 * This loses statistics on the fault but if we are unwilling to
-	 * migrate to this node, it is less likely we can do useful work
-	 */
-	if (migrate_ratelimited(numa_node_id()))
-		return;
-
 	start = mm->numa_scan_offset;
 	pages = sysctl_numa_balancing_scan_size;
 	pages <<= 20 - PAGE_SHIFT; /* MB in pages */
-- 
1.8.1.4

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