linux-kernel - [PATCH 57/63] sched: numa: Take false sharing into account when adapting scan rate

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Message-Id: <1381141781-10992-58-git-send-email-mgorman@suse.de>
Date:	Mon,  7 Oct 2013 11:29:35 +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 57/63] 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>
---
 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 baa2276..03698f5 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);
 	}
 
 	/*
-- 
1.8.4

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