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Subject[tip:sched/numa] mm/mpol: Make mempolicy home-node aware
Commit-ID:  a9ea2f1e496e4a5cf88e692948c62369efa37be5
Gitweb: http://git.kernel.org/tip/a9ea2f1e496e4a5cf88e692948c62369efa37be5
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Sat, 3 Mar 2012 17:05:54 +0100
Committer: Ingo Molnar <mingo@kernel.org>
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 <a.p.zijlstra@chello.nl>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Paul Turner <pjt@google.com>
Cc: Dan Smith <danms@us.ibm.com>
Cc: Bharata B Rao <bharata.rao@gmail.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-2jgh4xed0dejteh84gykmxff@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
mm/mempolicy.c | 29 +++++++++++++++++++++++++++--
1 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 1ddbf22..57fbc4c 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -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

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