sched, numa, mm: Add last_cpu to page flags

Introduce a per-page last_cpu field, fold this into the struct
page::flags field whenever possible.

The unlikely/rare 32bit NUMA configs will likely grow the page-frame.

[ Completely dropping 32bit support for CONFIG_NUMA_BALANCING would simplify
  things, but it would also remove the warning if we grow enough 64bit
  only page-flags to push the last-cpu out. ]

Suggested-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 182162960850c7b88532e06fdc25f26841cf8bb7..141a28fe472c31cf8a40f45beac8002625cda409 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -594,50 +594,11 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
  * sets it, so none of the operations on it need to be atomic.
  */
 
-
-/*
- * page->flags layout:
- *
- * There are three possibilities for how page->flags get
- * laid out.  The first is for the normal case, without
- * sparsemem.  The second is for sparsemem when there is
- * plenty of space for node and section.  The last is when
- * we have run out of space and have to fall back to an
- * alternate (slower) way of determining the node.
- *
- * No sparsemem or sparsemem vmemmap: |       NODE     | ZONE | ... | FLAGS |
- * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS |
- * classic sparse no space for node:  | SECTION |     ZONE    | ... | FLAGS |
- */
-#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
-#define SECTIONS_WIDTH         SECTIONS_SHIFT
-#else
-#define SECTIONS_WIDTH         0
-#endif
-
-#define ZONES_WIDTH            ZONES_SHIFT
-
-#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
-#define NODES_WIDTH            NODES_SHIFT
-#else
-#ifdef CONFIG_SPARSEMEM_VMEMMAP
-#error "Vmemmap: No space for nodes field in page flags"
-#endif
-#define NODES_WIDTH            0
-#endif
-
-/* Page flags: | [SECTION] | [NODE] | ZONE | ... | FLAGS | */
+/* Page flags: | [SECTION] | [NODE] | ZONE | [LAST_CPU] | ... | FLAGS | */
 #define SECTIONS_PGOFF         ((sizeof(unsigned long)*8) - SECTIONS_WIDTH)
 #define NODES_PGOFF            (SECTIONS_PGOFF - NODES_WIDTH)
 #define ZONES_PGOFF            (NODES_PGOFF - ZONES_WIDTH)
-
-/*
- * We are going to use the flags for the page to node mapping if its in
- * there.  This includes the case where there is no node, so it is implicit.
- */
-#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
-#define NODE_NOT_IN_PAGE_FLAGS
-#endif
+#define LAST_CPU_PGOFF         (ZONES_PGOFF - LAST_CPU_WIDTH)
 
 /*
  * Define the bit shifts to access each section.  For non-existent
@@ -647,6 +608,7 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
 #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_CPU_PGSHIFT       (LAST_CPU_PGOFF * (LAST_CPU_WIDTH != 0))
 
 /* NODE:ZONE or SECTION:ZONE is used to ID a zone for the buddy allocator */
 #ifdef NODE_NOT_IN_PAGE_FLAGS
@@ -668,6 +630,7 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
 #define ZONES_MASK             ((1UL << ZONES_WIDTH) - 1)
 #define NODES_MASK             ((1UL << NODES_WIDTH) - 1)
 #define SECTIONS_MASK          ((1UL << SECTIONS_WIDTH) - 1)
+#define LAST_CPU_MASK          ((1UL << LAST_CPU_WIDTH) - 1)
 #define ZONEID_MASK            ((1UL << ZONEID_SHIFT) - 1)
 
 static inline enum zone_type page_zonenum(const struct page *page)
@@ -706,6 +669,51 @@ static inline int page_to_nid(const struct page *page)
 }
 #endif
 
+#ifdef CONFIG_NUMA_BALANCING
+#ifdef LAST_CPU_NOT_IN_PAGE_FLAGS
+static inline int page_xchg_last_cpu(struct page *page, int cpu)
+{
+       return xchg(&page->_last_cpu, cpu);
+}
+
+static inline int page_last_cpu(struct page *page)
+{
+       return page->_last_cpu;
+}
+#else
+static inline int page_xchg_last_cpu(struct page *page, int cpu)
+{
+       unsigned long old_flags, flags;
+       int last_cpu;
+
+       do {
+               old_flags = flags = page->flags;
+               last_cpu = (flags >> LAST_CPU_PGSHIFT) & LAST_CPU_MASK;
+
+               flags &= ~(LAST_CPU_MASK << LAST_CPU_PGSHIFT);
+               flags |= (cpu & LAST_CPU_MASK) << LAST_CPU_PGSHIFT;
+       } while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags));
+
+       return last_cpu;
+}
+
+static inline int page_last_cpu(struct page *page)
+{
+       return (page->flags >> LAST_CPU_PGSHIFT) & LAST_CPU_MASK;
+}
+#endif /* LAST_CPU_NOT_IN_PAGE_FLAGS */
+#else /* CONFIG_NUMA_BALANCING */
+static inline int page_xchg_last_cpu(struct page *page, int cpu)
+{
+       return page_to_nid(page);
+}
+
+static inline int page_last_cpu(struct page *page)
+{
+       return page_to_nid(page);
+}
+#endif /* CONFIG_NUMA_BALANCING */
+
 static inline struct zone *page_zone(const struct page *page)
 {
        return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)];

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 31f8a3af7d942545562afd1fcacf11f52a4f82a0..7e9f758bf03ee5ff46d51f79deeef5b37195b3da 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -12,6 +12,7 @@
 #include <linux/cpumask.h>
 #include <linux/page-debug-flags.h>
 #include <linux/uprobes.h>
+#include <linux/page-flags-layout.h>
 #include <asm/page.h>
 #include <asm/mmu.h>
 
@@ -175,6 +176,10 @@ struct page {
         */
        void *shadow;
 #endif
+
+#ifdef LAST_CPU_NOT_IN_PAGE_FLAGS
+       int _last_cpu;
+#endif
 }
 /*
  * The struct page can be forced to be double word aligned so that atomic ops

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 50aaca81f63d6db3914b7858f0209fed036a5971..7e116ede1547390ba8f6860c75bd00b21a65a123 100644 (file)
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -15,7 +15,7 @@
 #include <linux/seqlock.h>
 #include <linux/nodemask.h>
 #include <linux/pageblock-flags.h>
-#include <generated/bounds.h>
+#include <linux/page-flags-layout.h>
 #include <linux/atomic.h>
 #include <asm/page.h>
 
@@ -318,16 +318,6 @@ enum zone_type {
  * match the requested limits. See gfp_zone() in include/linux/gfp.h
  */
 
-#if MAX_NR_ZONES < 2
-#define ZONES_SHIFT 0
-#elif MAX_NR_ZONES <= 2
-#define ZONES_SHIFT 1
-#elif MAX_NR_ZONES <= 4
-#define ZONES_SHIFT 2
-#else
-#error ZONES_SHIFT -- too many zones configured adjust calculation
-#endif
-
 struct zone {
        /* Fields commonly accessed by the page allocator */
 
@@ -1030,8 +1020,6 @@ static inline unsigned long early_pfn_to_nid(unsigned long pfn)
  * PA_SECTION_SHIFT            physical address to/from section number
  * PFN_SECTION_SHIFT           pfn to/from section number
  */
-#define SECTIONS_SHIFT         (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
-
 #define PA_SECTION_SHIFT       (SECTION_SIZE_BITS)
 #define PFN_SECTION_SHIFT      (SECTION_SIZE_BITS - PAGE_SHIFT)
 

diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
new file mode 100644 (file)
index 0000000..b258132
--- /dev/null
+++ b/include/linux/page-flags-layout.h
@@ -0,0 +1,83 @@
+#ifndef _LINUX_PAGE_FLAGS_LAYOUT
+#define _LINUX_PAGE_FLAGS_LAYOUT
+
+#include <linux/numa.h>
+#include <generated/bounds.h>
+
+#if MAX_NR_ZONES < 2
+#define ZONES_SHIFT 0
+#elif MAX_NR_ZONES <= 2
+#define ZONES_SHIFT 1
+#elif MAX_NR_ZONES <= 4
+#define ZONES_SHIFT 2
+#else
+#error ZONES_SHIFT -- too many zones configured adjust calculation
+#endif
+
+#ifdef CONFIG_SPARSEMEM
+#include <asm/sparsemem.h>
+
+/* 
+ * SECTION_SHIFT               #bits space required to store a section #
+ */
+#define SECTIONS_SHIFT         (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
+#endif
+
+/*
+ * page->flags layout:
+ *
+ * There are five possibilities for how page->flags get laid out.  The first
+ * (and second) is for the normal case, without sparsemem. The third is for
+ * sparsemem when there is plenty of space for node and section. The last is
+ * when we have run out of space and have to fall back to an alternate (slower)
+ * way of determining the node.
+ *
+ * No sparsemem or sparsemem vmemmap: |       NODE     | ZONE |            ... | FLAGS |
+ *     "      plus space for last_cpu:|       NODE     | ZONE | LAST_CPU | ... | FLAGS |
+ * classic sparse with space for node:| SECTION | NODE | ZONE |            ... | FLAGS |
+ *     "      plus space for last_cpu:| SECTION | NODE | ZONE | LAST_CPU | ... | FLAGS |
+ * classic sparse no space for node:  | SECTION |     ZONE    |            ... | FLAGS |
+ */
+#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
+
+#define SECTIONS_WIDTH         SECTIONS_SHIFT
+#else
+#define SECTIONS_WIDTH         0
+#endif
+
+#define ZONES_WIDTH            ZONES_SHIFT
+
+#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
+#define NODES_WIDTH            NODES_SHIFT
+#else
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+#error "Vmemmap: No space for nodes field in page flags"
+#endif
+#define NODES_WIDTH            0
+#endif
+
+#ifdef CONFIG_NUMA_BALANCING
+#define LAST_CPU_SHIFT NR_CPUS_BITS
+#else
+#define LAST_CPU_SHIFT 0
+#endif
+
+#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPU_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
+#define LAST_CPU_WIDTH LAST_CPU_SHIFT
+#else
+#define LAST_CPU_WIDTH 0
+#endif
+
+/*
+ * We are going to use the flags for the page to node mapping if its in
+ * there.  This includes the case where there is no node, so it is implicit.
+ */
+#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
+#define NODE_NOT_IN_PAGE_FLAGS
+#endif
+
+#if defined(CONFIG_NUMA_BALANCING) && LAST_CPU_WIDTH == 0
+#define LAST_CPU_NOT_IN_PAGE_FLAGS
+#endif
+
+#endif /* _LINUX_PAGE_FLAGS_LAYOUT */

diff --git a/kernel/bounds.c b/kernel/bounds.c
index 0c9b862292b26dc0494f771f96532fd8995c2b3b..e8ca97b5c386dc8a7e5374ab0aae48091fc30b6d 100644 (file)
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -10,6 +10,7 @@
 #include <linux/mmzone.h>
 #include <linux/kbuild.h>
 #include <linux/page_cgroup.h>
+#include <linux/log2.h>
 
 void foo(void)
 {
@@ -17,5 +18,8 @@ void foo(void)
        DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS);
        DEFINE(MAX_NR_ZONES, __MAX_NR_ZONES);
        DEFINE(NR_PCG_FLAGS, __NR_PCG_FLAGS);
+#ifdef CONFIG_SMP
+       DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS));
+#endif
        /* End of constants */
 }

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 931caf4d6e275a119044a017fcc8ec272f81ad7e..fbff71810ac42b54e8a07abde2f6aeb40ef453ac 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -745,6 +745,7 @@ void do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
        struct page *new_page = NULL;
        struct page *page = NULL;
        int node, lru;
+       int last_cpu;
 
        spin_lock(&mm->page_table_lock);
        if (unlikely(!pmd_same(*pmd, entry)))
@@ -759,6 +760,7 @@ void do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
        page = pmd_page(entry);
        if (page) {
                VM_BUG_ON(!PageCompound(page) || !PageHead(page));
+               last_cpu = page_last_cpu(page);
 
                get_page(page);
                node = mpol_misplaced(page, vma, haddr);
@@ -1440,6 +1442,7 @@ static void __split_huge_page_refcount(struct page *page)
                page_tail->mapping = page->mapping;
 
                page_tail->index = page->index + i;
+               page_xchg_last_cpu(page, page_last_cpu(page_tail));
 
                BUG_ON(!PageAnon(page_tail));
                BUG_ON(!PageUptodate(page_tail));

diff --git a/mm/memory.c b/mm/memory.c
index 0d26a281bee22102fcb76f035fc57e59c0a18abe..1b9108ca10dd601497ba8a51bb06497d011f6b28 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -68,6 +68,10 @@
 
 #include "internal.h"
 
+#ifdef LAST_CPU_NOT_IN_PAGE_FLAGS
+#warning Unfortunate NUMA config, growing page-frame for last_cpu.
+#endif
+
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 /* use the per-pgdat data instead for discontigmem - mbligh */
 unsigned long max_mapnr;