linux-kernel - [PATCH 41/43] sched: numa: Rename mempolicy to HOME

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Date:	Fri, 16 Nov 2012 11:22:51 +0000
From:	Mel Gorman <mgorman@...e.de>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Ingo Molnar <mingo@...nel.org>
Cc:	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Hugh Dickins <hughd@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>
Subject: [PATCH 41/43] sched: numa: Rename mempolicy to HOME

Rename the policy to reflect that while allocations and migrations are
based on reference that the home node is taken into account for
migration decisions.

Signed-off-by: Mel Gorman <mgorman@...e.de>
---
 include/uapi/linux/mempolicy.h |    9 ++++++++-
 mm/mempolicy.c                 |    9 ++++++---
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h
index 0d11c3d..4506772 100644
--- a/include/uapi/linux/mempolicy.h
+++ b/include/uapi/linux/mempolicy.h
@@ -67,7 +67,14 @@ enum mpol_rebind_step {
 #define MPOL_F_LOCAL   (1 << 1)	/* preferred local allocation */
 #define MPOL_F_REBINDING (1 << 2)	/* identify policies in rebinding */
 #define MPOL_F_MOF	(1 << 3) /* this policy wants migrate on fault */
-#define MPOL_F_MORON	(1 << 4) /* Migrate On pte_numa Reference On Node */
+#define MPOL_F_HOME	(1 << 4) /*
+				  * Migrate towards referencing node.
+				  * By building up stats on faults, the
+				  * scheduler will reinforce the choice
+				  * by identifying a home node and
+				  * queueing the task on that node
+				  * where possible.
+				  */
 
 
 #endif /* _UAPI_LINUX_MEMPOLICY_H */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 648423a..c6f85eb 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2452,8 +2452,11 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
 		BUG();
 	}
 
-	/* Migrate the page towards the node whose CPU is referencing it */
-	if (pol->flags & MPOL_F_MORON) {
+	/*
+	 * Migrate pages towards their referencing node. Based on the fault
+	 * statistics a home node will be chosen by the scheduler
+	 */
+	if (pol->flags & MPOL_F_HOME) {
 		int last_nid;
 
 		polnid = numa_node_id();
@@ -2676,7 +2679,7 @@ void __init numa_policy_init(void)
 		preferred_node_policy[nid] = (struct mempolicy) {
 			.refcnt = ATOMIC_INIT(1),
 			.mode = MPOL_PREFERRED,
-			.flags = MPOL_F_MOF | MPOL_F_MORON,
+			.flags = MPOL_F_MOF | MPOL_F_HOME,
 			.v = { .preferred_node = nid, },
 		};
 	}
-- 
1.7.9.2

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