On Tue, 2012-07-31 at 21:12 +0200, Peter Zijlstra wrote:
> +#ifdef CONFIG_NUMA
> + /*
> + * XXX fold this into flags for 64bit or so...
> + */
> + int nid_last;
> +#endif
Something like the below? I still ought to update all the various
comments about page flag layout etc..
Also, that #warning gives a very noisy build indeed, I guess we should
either make it silent or increase the page frame size for those
configs.. 32bit NUMA is quite rare for normal people (sorry Paul) :)
---
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -611,10 +611,19 @@ static inline pte_t maybe_mkwrite(pte_t
#define NODES_WIDTH 0
#endif
+#if NODES_WIDTH && (SECTIONS_WIDTH+ZONES_WIDTH+2*NODES_SHIFT <= BITS_PER_LONG
- NR_PAGEFLAGS)
+#define LAST_NID_WIDTH NODES_SHIFT
+#else
+#warning "faking page_xchg_last_nid"
+#define LAST_NID_NOT_IN_PAGE_FLAGS
+#define LAST_NID_WIDTH 0
+#endif
+
/* Page flags: | [SECTION] | [NODE] | ZONE | ... | FLAGS | */
#define SECTIONS_PGOFF ((sizeof(unsigned long)*8) - SECTIONS_WIDTH)
#define NODES_PGOFF (SECTIONS_PGOFF - NODES_WIDTH)
#define ZONES_PGOFF (NODES_PGOFF - ZONES_WIDTH)
+#define LAST_NID_PGOFF (ZONES_PGOFF - LAST_NID_WIDTH)
/*
* We are going to use the flags for the page to node mapping if its in
@@ -632,6 +641,7 @@ static inline pte_t maybe_mkwrite(pte_t
#define SECTIONS_PGSHIFT (SECTIONS_PGOFF * (SECTIONS_WIDTH != 0))
#define NODES_PGSHIFT (NODES_PGOFF * (NODES_WIDTH != 0))
#define ZONES_PGSHIFT (ZONES_PGOFF * (ZONES_WIDTH != 0))
+#define LAST_NID_PGSHIFT (LAST_NID_PGOFF * (LAST_NID_WIDTH != 0))
/* NODE:ZONE or SECTION:ZONE is used to ID a zone for the buddy allocator */
#ifdef NODE_NOT_IN_PAGE_FLAGS
@@ -653,6 +663,7 @@ static inline pte_t maybe_mkwrite(pte_t
#define ZONES_MASK ((1UL << ZONES_WIDTH) - 1)
#define NODES_MASK ((1UL << NODES_WIDTH) - 1)
#define SECTIONS_MASK ((1UL << SECTIONS_WIDTH) - 1)
+#define LAST_NID_MASK ((1UL << LAST_NID_WIDTH) - 1)
#define ZONEID_MASK ((1UL << ZONEID_SHIFT) - 1)
static inline enum zone_type page_zonenum(const struct page *page)
@@ -691,6 +702,39 @@ static inline int page_to_nid(const stru
}
#endif
+#ifdef LAST_NID_NOT_IN_PAGE_FLAGS
+static inline int page_xchg_last_nid(struct page *page, int nid)
+{
+ return nid; /* fakin' it */
+}
+
+static inline int page_last_nid(struct page *page)
+{
+ return page_to_nid(page);
+}
+#else
+static inline int page_xchg_last_nid(struct page *page, int nid)
+{
+ unsigned long old_flags, flags;
+ int last_nid;
+
+ old_flags = flags = page->flags;
+ last_nid = (flags >> LAST_NID_PGSHIFT) & LAST_NID_MASK;
+
+ flags &= ~(LAST_NID_MASK << LAST_NID_PGSHIFT);
+ flags |= (nid & LAST_NID_MASK) << LAST_NID_PGSHIFT;
+
+ (void)cmpxchg(&page->flags, old_flags, flags);
+
+ return last_nid;
+}
+
+static inline int page_last_nid(struct page *page)
+{
+ return (page->flags >> LAST_NID_PGSHIFT) & LAST_NID_MASK;
+}
+#endif /* LAST_NID_NOT_IN_PAGE_FLAGS */
+
static inline struct zone *page_zone(const struct page *page)
{
return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)];
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -176,12 +176,6 @@ struct page {
*/
void *shadow;
#endif
-#ifdef CONFIG_NUMA
- /*
- * XXX fold this into flags for 64bit or so...
- */
- int nid_last;
-#endif
}
/*
* The struct page can be forced to be double word aligned so that atomic ops
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1366,6 +1366,7 @@ static void __split_huge_page_refcount(s
page_tail->mapping = page->mapping;
page_tail->index = page->index + i;
+ page_xchg_last_nid(page, page_last_nid(tail_page));
page_tail->nid_last = page->nid_last;
BUG_ON(!PageAnon(page_tail));
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2265,10 +2265,9 @@ int mpol_misplaced(struct page *page, st
* task_tick_numa().
*/
if (multi && (pol->flags & MPOL_F_HOME)) {
- if (page->nid_last != polnid) {
- page->nid_last = polnid;
+ int last_nid = page_xchg_last_nid(page, polnid);
+ if (last_nid != polnid)
goto out;
- }
}
if (curnid != polnid)
--
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