Re: [RFC][PATCH 02/26] mm, mpol: Remove NUMA_INTERLEAVE_HIT

Since the NUMA_INTERLEAVE_HIT statistic is useless on its own; it wants
to be compared to either a total of interleave allocations or to a miss
count, remove it.

Fixing it would be possible, but since we've gone years without these
statistics I figure we can continue that way.

This cleans up some of the weird MPOL_INTERLEAVE allocation exceptions.

Signed-off-by: Peter Zijlstra <redacted>
---
 drivers/base/node.c    |    2 +-
 include/linux/mmzone.h |    1 -
 mm/mempolicy.c         |   66 +++++++++++++++--------------------------------
 3 files changed, 22 insertions(+), 47 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 5693ece..942cdbc 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c

@@ -172,7 +172,7 @@ static ssize_t node_read_numastat(struct sys_device * dev,
                       node_page_state(dev->id, NUMA_HIT),
                       node_page_state(dev->id, NUMA_MISS),
                       node_page_state(dev->id, NUMA_FOREIGN),
-                      node_page_state(dev->id, NUMA_INTERLEAVE_HIT),
+                      0UL,
                       node_page_state(dev->id, NUMA_LOCAL),
                       node_page_state(dev->id, NUMA_OTHER));
 }

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3ac040f..3a3be81 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h

@@ -111,7 +111,6 @@ enum zone_stat_item {
        NUMA_HIT,               /* allocated in intended node */
        NUMA_MISS,              /* allocated in non intended node */
        NUMA_FOREIGN,           /* was intended here, hit elsewhere */
-       NUMA_INTERLEAVE_HIT,    /* interleaver preferred this zone */
        NUMA_LOCAL,             /* allocation from local node */
        NUMA_OTHER,             /* allocation from other node */
 #endif

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c3fdbcb..2c48c45 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c

@@ -1530,11 +1530,29 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
        return NULL;
 }

+/* Do dynamic interleaving for a process */
+static unsigned interleave_nodes(struct mempolicy *policy)
+{
+       unsigned nid, next;
+       struct task_struct *me = current;
+
+       nid = me->il_next;
+       next = next_node(nid, policy->v.nodes);
+       if (next >= MAX_NUMNODES)
+               next = first_node(policy->v.nodes);
+       if (next < MAX_NUMNODES)
+               me->il_next = next;
+       return nid;
+}
+
 /* Return a zonelist indicated by gfp for node representing a mempolicy */
 static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
        int nd)
 {
        switch (policy->mode) {
+       case MPOL_INTERLEAVE:
+               nd = interleave_nodes(policy);

+               break;
        case MPOL_PREFERRED:
                if (!(policy->flags & MPOL_F_LOCAL))
                        nd = policy->v.preferred_node;

@@ -1556,21 +1574,6 @@ static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
        return node_zonelist(nd, gfp);
 }

-/* Do dynamic interleaving for a process */
-static unsigned interleave_nodes(struct mempolicy *policy)
-{
-       unsigned nid, next;
-       struct task_struct *me = current;
-
-       nid = me->il_next;
-       next = next_node(nid, policy->v.nodes);
-       if (next >= MAX_NUMNODES)
-               next = first_node(policy->v.nodes);
-       if (next < MAX_NUMNODES)
-               me->il_next = next;
-       return nid;
-}
-
 /*
  * Depending on the memory policy provide a node from which to allocate the
  * next slab entry.

@@ -1801,21 +1804,6 @@ out:
        return ret;
 }

-/* Allocate a page in interleaved policy.
-   Own path because it needs to do special accounting. */
-static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
-                                       unsigned nid)
-{
-       struct zonelist *zl;
-       struct page *page;
-
-       zl = node_zonelist(nid, gfp);
-       page = __alloc_pages(gfp, order, zl);
-       if (page && page_zone(page) == zonelist_zone(&zl->_zonerefs[0]))
-               inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
-       return page;
-}
-
 /**
  *     alloc_pages_vma - Allocate a page for a VMA.
  *

@@ -1848,15 +1836,6 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
        struct page *page;

        get_mems_allowed();
-       if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
-               unsigned nid;
-
-               nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
-               mpol_cond_put(pol);
-               page = alloc_page_interleave(gfp, order, nid);
-               put_mems_allowed();
-               return page;
-       }
        zl = policy_zonelist(gfp, pol, node);
        if (unlikely(mpol_needs_cond_ref(pol))) {
                /*

@@ -1909,12 +1888,9 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
         * No reference counting needed for current->mempolicy
         * nor system default_policy
         */
-       if (pol->mode == MPOL_INTERLEAVE)
-               page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
-       else
-               page = __alloc_pages_nodemask(gfp, order,
-                               policy_zonelist(gfp, pol, numa_node_id()),
-                               policy_nodemask(gfp, pol));
+       page = __alloc_pages_nodemask(gfp, order,
+                       policy_zonelist(gfp, pol, numa_node_id()),
+                       policy_nodemask(gfp, pol));
        put_mems_allowed();
        return page;
 }



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