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Subject[PATCH 29/33] sched, mm, mempolicy: Add per task mempolicy
Date
We are going to make use of it in the NUMA code: each thread will
converge not just to a group of related tasks, but to a specific
group of memory nodes as well.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/mempolicy.h | 39 +--------------------------------------
include/linux/mm_types.h | 40 ++++++++++++++++++++++++++++++++++++++++
include/linux/sched.h | 3 ++-
kernel/sched/core.c | 7 +++++++
mm/mempolicy.c | 16 +++-------------
5 files changed, 53 insertions(+), 52 deletions(-)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index c511e25..f44b7f3 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -6,11 +6,11 @@
#define _LINUX_MEMPOLICY_H 1


+#include <linux/mm_types.h>
#include <linux/mmzone.h>
#include <linux/slab.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
-#include <linux/nodemask.h>
#include <linux/pagemap.h>
#include <uapi/linux/mempolicy.h>

@@ -19,43 +19,6 @@ struct mm_struct;
#ifdef CONFIG_NUMA

/*
- * Describe a memory policy.
- *
- * A mempolicy can be either associated with a process or with a VMA.
- * For VMA related allocations the VMA policy is preferred, otherwise
- * the process policy is used. Interrupts ignore the memory policy
- * of the current process.
- *
- * Locking policy for interlave:
- * In process context there is no locking because only the process accesses
- * its own state. All vma manipulation is somewhat protected by a down_read on
- * mmap_sem.
- *
- * Freeing policy:
- * Mempolicy objects are reference counted. A mempolicy will be freed when
- * mpol_put() decrements the reference count to zero.
- *
- * Duplicating policy objects:
- * mpol_dup() allocates a new mempolicy and copies the specified mempolicy
- * to the new storage. The reference count of the new object is initialized
- * to 1, representing the caller of mpol_dup().
- */
-struct mempolicy {
- atomic_t refcnt;
- unsigned short mode; /* See MPOL_* above */
- unsigned short flags; /* See set_mempolicy() MPOL_F_* above */
- union {
- short preferred_node; /* preferred */
- nodemask_t nodes; /* interleave/bind */
- /* undefined for default */
- } v;
- union {
- nodemask_t cpuset_mems_allowed; /* relative to these nodes */
- nodemask_t user_nodemask; /* nodemask passed by user */
- } w;
-};
-
-/*
* Support for managing mempolicy data objects (clone, copy, destroy)
* The default fast path of a NULL MPOL_DEFAULT policy is always inlined.
*/
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 5995652..cd2be76 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -13,6 +13,7 @@
#include <linux/page-debug-flags.h>
#include <linux/uprobes.h>
#include <linux/page-flags-layout.h>
+#include <linux/nodemask.h>
#include <asm/page.h>
#include <asm/mmu.h>

@@ -203,6 +204,45 @@ struct page_frag {

typedef unsigned long __nocast vm_flags_t;

+#ifdef CONFIG_NUMA
+/*
+ * Describe a memory policy.
+ *
+ * A mempolicy can be either associated with a process or with a VMA.
+ * For VMA related allocations the VMA policy is preferred, otherwise
+ * the process policy is used. Interrupts ignore the memory policy
+ * of the current process.
+ *
+ * Locking policy for interlave:
+ * In process context there is no locking because only the process accesses
+ * its own state. All vma manipulation is somewhat protected by a down_read on
+ * mmap_sem.
+ *
+ * Freeing policy:
+ * Mempolicy objects are reference counted. A mempolicy will be freed when
+ * mpol_put() decrements the reference count to zero.
+ *
+ * Duplicating policy objects:
+ * mpol_dup() allocates a new mempolicy and copies the specified mempolicy
+ * to the new storage. The reference count of the new object is initialized
+ * to 1, representing the caller of mpol_dup().
+ */
+struct mempolicy {
+ atomic_t refcnt;
+ unsigned short mode; /* See MPOL_* above */
+ unsigned short flags; /* See set_mempolicy() MPOL_F_* above */
+ union {
+ short preferred_node; /* preferred */
+ nodemask_t nodes; /* interleave/bind */
+ /* undefined for default */
+ } v;
+ union {
+ nodemask_t cpuset_mems_allowed; /* relative to these nodes */
+ nodemask_t user_nodemask; /* nodemask passed by user */
+ } w;
+};
+#endif
+
/*
* A region containing a mapping of a non-memory backed file under NOMMU
* conditions. These are held in a global tree and are pinned by the VMAs that
diff --git a/include/linux/sched.h b/include/linux/sched.h
index be73297..696492e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1516,7 +1516,8 @@ struct task_struct {

struct task_struct *shared_buddy, *shared_buddy_curr;
unsigned long shared_buddy_faults, shared_buddy_faults_curr;
- int ideal_cpu, ideal_cpu_curr;
+ int ideal_cpu, ideal_cpu_curr, ideal_cpu_candidate;
+ struct mempolicy numa_policy;

#endif /* CONFIG_NUMA_BALANCING */

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 39cf991..794efa0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -72,6 +72,7 @@
#include <linux/slab.h>
#include <linux/init_task.h>
#include <linux/binfmts.h>
+#include <uapi/linux/mempolicy.h>

#include <asm/switch_to.h>
#include <asm/tlb.h>
@@ -1563,6 +1564,12 @@ static void __sched_fork(struct task_struct *p)
p->shared_buddy_faults = 0;
p->ideal_cpu = -1;
p->ideal_cpu_curr = -1;
+ atomic_set(&p->numa_policy.refcnt, 1);
+ p->numa_policy.mode = MPOL_INTERLEAVE;
+ p->numa_policy.flags = 0;
+ p->numa_policy.v.preferred_node = 0;
+ p->numa_policy.v.nodes = node_online_map;
+
#endif /* CONFIG_NUMA_BALANCING */
}

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 02890f2..d71a93d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -118,20 +118,12 @@ static struct mempolicy default_policy_local = {
.flags = MPOL_F_LOCAL,
};

-/*
- * .v.nodes is set by numa_policy_init():
- */
-static struct mempolicy default_policy_shared = {
- .refcnt = ATOMIC_INIT(1), /* never free it */
- .mode = MPOL_INTERLEAVE,
- .flags = 0,
-};
-
static struct mempolicy *default_policy(void)
{
+#ifdef CONFIG_NUMA_BALANCING
if (task_numa_shared(current) == 1)
- return &default_policy_shared;
-
+ return &current->numa_policy;
+#endif
return &default_policy_local;
}

@@ -2518,8 +2510,6 @@ void __init numa_policy_init(void)
sizeof(struct sp_node),
0, SLAB_PANIC, NULL);

- default_policy_shared.v.nodes = node_online_map;
-
/*
* Set interleaving policy for system init. Interleaving is only
* enabled across suitably sized nodes (default is >= 16MB), or
--
1.7.11.7


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