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mm/mpol: Make mempolicy home-node aware

tip:sched/numa tip-bot for Peter Zijlstra 1 participant 1 message May 18, 2012

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Commit-ID:  a9ea2f1e496e4a5cf88e692948c62369efa37be5
Gitweb:     http://git.kernel.org/tip/a9ea2f1e496e4a5cf88e692948c62369efa37be5
Author:     Peter Zijlstra <[email protected]>
AuthorDate: Sat, 3 Mar 2012 17:05:54 +0100
Committer:  Ingo Molnar <[email protected]>
CommitDate: Fri, 18 May 2012 08:16:21 +0200

mm/mpol: Make mempolicy home-node aware

Add another layer of fallback policy to make the home node concept useful from a memory allocation PoV.

This changes the mpol order to:

- vma->vm_ops->get_policy [if applicable]
- vma->vm_policy [if applicable]
- task->mempolicy
- tsk_home_node() preferred [NEW]
- default_policy

Note that the tsk_home_node() policy has Migrate-on-Fault enabled to facilitate efficient on-demand memory migration.

Signed-off-by Peter Zijlstra <[email protected]>
Cc Suresh Siddha <[email protected]>
Cc Paul Turner <[email protected]>
Cc Dan Smith <[email protected]>
Cc Bharata B Rao <[email protected]>
Cc Lee Schermerhorn <[email protected]>
Cc Christoph Lameter <[email protected]>
Cc Rik van Riel <[email protected]>
Cc Andrea Arcangeli <[email protected]>
Cc Andrew Morton <[email protected]>
Cc Linus Torvalds <[email protected]>
Link http://lkml.kernel.org/n/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
---
 mm/mempolicy.c |   29 +++++++++++++++++++++++++++--
 1 files changed, 27 insertions(+), 2 deletions(-)
mm/mempolicy.c +27 -2
index 1ddbf22..57fbc4c 100644
@@ -117,6 +117,22 @@ static struct mempolicy default_policy = {
 	.flags = MPOL_F_LOCAL,
 };
 
+static struct mempolicy preferred_node_policy[MAX_NUMNODES];
+
+static struct mempolicy *get_task_policy(struct task_struct *p)
+{
+	struct mempolicy *pol = p->mempolicy;
+	int node;
+
+	if (!pol) {
+		node = tsk_home_node(p);
+		if (node != -1)
+			pol = &preferred_node_policy[node];
+	}
+
+	return pol;
+}
+
 static const struct mempolicy_operations {
 	int (*create)(struct mempolicy *pol, const nodemask_t *nodes);
 	/*

@@ -1506,7 +1522,7 @@ asmlinkage long compat_sys_mbind(compat_ulong_t start, compat_ulong_t len,
 struct mempolicy *get_vma_policy(struct task_struct *task,
 		struct vm_area_struct *vma, unsigned long addr)
 {
-	struct mempolicy *pol = task->mempolicy;
+	struct mempolicy *pol = get_task_policy(task);
 
 	if (vma) {
 		if (vma->vm_ops && vma->vm_ops->get_policy) {

@@ -1890,7 +1906,7 @@ retry_cpuset:
  */
 struct page *alloc_pages_current(gfp_t gfp, unsigned order)
 {
-	struct mempolicy *pol = current->mempolicy;
+	struct mempolicy *pol = get_task_policy(current);
 	struct page *page;
 	unsigned int cpuset_mems_cookie;
 

@@ -2358,6 +2374,15 @@ void __init numa_policy_init(void)
 				     sizeof(struct sp_node),
 				     0, SLAB_PANIC, NULL);
 
+	for_each_node(nid) {
+		preferred_node_policy[nid] = (struct mempolicy) {
+			.refcnt = ATOMIC_INIT(1),
+			.mode = MPOL_PREFERRED,
+			.flags = MPOL_F_MOF,
+			.v = { .preferred_node = nid, },
+		};
+	}
+
 	/*
 	 * Set interleaving policy for system init. Interleaving is only
 	 * enabled across suitably sized nodes (default is >= 16MB), or