linux-kernel - [tip:sched/core] sched/numa: Take false sharing into account when adapting scan rate

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Date:	Wed, 9 Oct 2013 10:33:22 -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:
  Take false sharing into account when adapting scan rate

Commit-ID:  3e6a9418cf05638b103e34f5d13be0321872e623
Gitweb:     http://git.kernel.org/tip/3e6a9418cf05638b103e34f5d13be0321872e623
Author:     Mel Gorman <mgorman@...e.de>
AuthorDate: Mon, 7 Oct 2013 11:29:35 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 9 Oct 2013 14:48:14 +0200

sched/numa: Take false sharing into account when adapting scan rate

Scan rate is altered based on whether shared/private faults dominated.
task_numa_group() may detect false sharing but that information is not
taken into account when adapting the scan rate. Take it into account.

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/1381141781-10992-58-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/fair.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 222c2d0..d26a16e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1381,7 +1381,8 @@ static void double_lock(spinlock_t *l1, spinlock_t *l2)
 	spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
 }
 
-static void task_numa_group(struct task_struct *p, int cpupid, int flags)
+static void task_numa_group(struct task_struct *p, int cpupid, int flags,
+			int *priv)
 {
 	struct numa_group *grp, *my_grp;
 	struct task_struct *tsk;
@@ -1447,6 +1448,9 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags)
 	if (flags & TNF_SHARED)
 		join = true;
 
+	/* Update priv based on whether false sharing was detected */
+	*priv = !join;
+
 	if (join && !get_numa_group(grp))
 		join = false;
 
@@ -1545,7 +1549,7 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags)
 	} else {
 		priv = cpupid_match_pid(p, last_cpupid);
 		if (!priv && !(flags & TNF_NO_GROUP))
-			task_numa_group(p, last_cpupid, flags);
+			task_numa_group(p, last_cpupid, flags, &priv);
 	}
 
 	/*
--
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