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Subject[PATCH 37/52] sched, numa, mm: Interleave shared tasks
Date
Interleave tasks that are 'shared' - i.e. whose memory access patterns
indicate that they are intensively sharing memory with other tasks.

If such a task ends up converging then it switches back into the lazy
node-local policy.

Build-Bug-Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
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>
---
mm/mempolicy.c | 55 +++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 41 insertions(+), 14 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index ad683b9..a847b10 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -112,12 +112,29 @@ enum zone_type policy_zone = 0;
/*
* run-time system-wide default policy => local allocation
*/
-static struct mempolicy default_policy = {
- .refcnt = ATOMIC_INIT(1), /* never free it */
- .mode = MPOL_PREFERRED,
- .flags = MPOL_F_LOCAL,
+static struct mempolicy default_policy_local = {
+ .refcnt = ATOMIC_INIT(1), /* never free it */
+ .mode = MPOL_PREFERRED,
+ .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)
+{
+ if (task_numa_shared(current) == 1)
+ return &default_policy_shared;
+
+ return &default_policy_local;
+}
+
static struct mempolicy preferred_node_policy[MAX_NUMNODES];

static struct mempolicy *get_task_policy(struct task_struct *p)
@@ -855,7 +872,7 @@ out:
static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
{
nodes_clear(*nodes);
- if (p == &default_policy)
+ if (p == default_policy())
return;

switch (p->mode) {
@@ -930,7 +947,7 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
return -EINVAL;

if (!pol)
- pol = &default_policy; /* indicates default behavior */
+ pol = default_policy(); /* indicates default behavior */

if (flags & MPOL_F_NODE) {
if (flags & MPOL_F_ADDR) {
@@ -946,7 +963,7 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
goto out;
}
} else {
- *policy = pol == &default_policy ? MPOL_DEFAULT :
+ *policy = pol == default_policy() ? MPOL_DEFAULT :
pol->mode;
/*
* Internal mempolicy flags must be masked off before exposing
@@ -1640,7 +1657,7 @@ struct mempolicy *get_vma_policy(struct task_struct *task,
}
}
if (!pol)
- pol = &default_policy;
+ pol = default_policy();
return pol;
}

@@ -2046,7 +2063,7 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
unsigned int cpuset_mems_cookie;

if (!pol || in_interrupt() || (gfp & __GFP_THISNODE))
- pol = &default_policy;
+ pol = default_policy();

retry_cpuset:
cpuset_mems_cookie = get_mems_allowed();
@@ -2269,7 +2286,6 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
struct mempolicy *pol;
struct zone *zone;
int page_nid = page_to_nid(page);
- unsigned long pgoff;
int target_node = page_nid;

BUG_ON(!vma);
@@ -2280,13 +2296,22 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long

switch (pol->mode) {
case MPOL_INTERLEAVE:
+ {
+ int shift;
+
BUG_ON(addr >= vma->vm_end);
BUG_ON(addr < vma->vm_start);

- pgoff = vma->vm_pgoff;
- pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
- target_node = offset_il_node(pol, vma, pgoff);
+#ifdef CONFIG_HUGETLB_PAGE
+ if (transparent_hugepage_enabled(vma) || vma->vm_flags & VM_HUGETLB)
+ shift = HPAGE_SHIFT;
+ else
+#endif
+ shift = PAGE_SHIFT;
+
+ target_node = interleave_nid(pol, vma, addr, shift);
break;
+ }

case MPOL_PREFERRED:
if (pol->flags & MPOL_F_LOCAL)
@@ -2552,6 +2577,8 @@ void __init numa_policy_init(void)
};
}

+ 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
@@ -2771,7 +2798,7 @@ int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
*/
VM_BUG_ON(maxlen < strlen("interleave") + strlen("relative") + 16);

- if (!pol || pol == &default_policy)
+ if (!pol || pol == default_policy())
mode = MPOL_DEFAULT;
else
mode = pol->mode;
--
1.7.11.7


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