[PATCH 29/33] autonuma: page_autonuma

[PATCH 29/33] autonuma: page_autonuma

[Andrea Arcangeli]

Move the autonuma_last_nid from the "struct page" to a separate
page_autonuma data structure allocated in the memsection (with
sparsemem) or in the pgdat (with flatmem).

This is done to avoid growing the size of "struct page". The
page_autonuma data is only allocated if the kernel is booted on real
NUMA hardware and noautonuma is not passed as a parameter to the
kernel.

An alternative would be to takeover 16 bits from the page->flags: but:

1) 32bit are already used (in fact 32bit archs are considering to
   adding another 32bit too to avoid losing common code features), 16
   bits would be used by the last_nid, and several bits are used by
   per-node (readonly) zone/node information, so we would be left with
   just an handful of spare PG_ bits if we stole 16 for the last_nid.

2) We cannot exclude we'll want to add more bits of information in the
   future (and more than 16 wouldn't fit on page->flags). Changing the
   format or layout of the page_autonuma structure is trivial,
   compared to altering the format of the page->flags. So
   page_autonuma is much more hackable than page->flags.

3) page->flags can be modified from under us with locked ops
   (lock_page and all page flags operations). Normally we never change
   more than 1 bit at once on it. So the way page->flags could be
   updated is through cmpxchg. That's slow and tricky code would need
   to be written for it (potentially to drop late in case of point 2
   above). Allocating those 2 bytes separately to me looks a lot
   cleaner even if it takes 0.048% of memory (but only when booting on
   NUMA hardware).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
 include/linux/autonuma.h       |    8 ++
 include/linux/autonuma_types.h |   19 +++
 include/linux/mm_types.h       |   11 --
 include/linux/mmzone.h         |   12 ++
 include/linux/page_autonuma.h  |   50 +++++++++
 init/main.c                    |    2 +
 mm/Makefile                    |    2 +-
 mm/autonuma.c                  |   37 +++++--
 mm/huge_memory.c               |   13 ++-
 mm/page_alloc.c                |   14 +--
 mm/page_autonuma.c             |  237 ++++++++++++++++++++++++++++++++++++++++
 mm/sparse.c                    |  126 ++++++++++++++++++++-
 12 files changed, 490 insertions(+), 41 deletions(-)
 create mode 100644 include/linux/page_autonuma.h
 create mode 100644 mm/page_autonuma.c

diff --git a/include/linux/autonuma.h b/include/linux/autonuma.h
index 02d4875..274c616 100644
--- a/include/linux/autonuma.h
+++ b/include/linux/autonuma.h
@@ -10,6 +10,13 @@ extern void autonuma_exit(struct mm_struct *mm);
 extern void autonuma_migrate_split_huge_page(struct page *page,
 					     struct page *page_tail);
 extern void autonuma_setup_new_exec(struct task_struct *p);
+extern struct page_autonuma *lookup_page_autonuma(struct page *page);
+
+static inline void autonuma_free_page(struct page *page)
+{
+	if (autonuma_possible())
+		lookup_page_autonuma(page)->autonuma_last_nid = -1;
+}
 
 #define autonuma_printk(format, args...) \
 	if (autonuma_debug()) printk(format, ##args)
@@ -21,6 +28,7 @@ static inline void autonuma_exit(struct mm_struct *mm) {}
 static inline void autonuma_migrate_split_huge_page(struct page *page,
 						    struct page *page_tail) {}
 static inline void autonuma_setup_new_exec(struct task_struct *p) {}
+static inline void autonuma_free_page(struct page *page) {}
 
 #endif /* CONFIG_AUTONUMA */
 
diff --git a/include/linux/autonuma_types.h b/include/linux/autonuma_types.h
index 9673ce8..d0c6403 100644
--- a/include/linux/autonuma_types.h
+++ b/include/linux/autonuma_types.h
@@ -78,6 +78,25 @@ struct task_autonuma {
 	/* do not add more variables here, the above array size is dynamic */
 };
 
+/*
+ * Per page (or per-pageblock) structure dynamically allocated only if
+ * autonuma is possible.
+ */
+struct page_autonuma {
+	/*
+	 * autonuma_last_nid records the NUMA node that accessed the
+	 * page during the last NUMA hinting page fault. If a
+	 * different node accesses the page next, AutoNUMA will not
+	 * migrate the page. This tries to avoid page thrashing by
+	 * requiring that a page be accessed by the same node twice in
+	 * a row before it is queued for migration.
+	 */
+#if MAX_NUMNODES > 32767
+#error "too many nodes"
+#endif
+	short autonuma_last_nid;
+};
+
 extern int alloc_task_autonuma(struct task_struct *tsk,
 			       struct task_struct *orig,
 			       int node);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 9e8398a..c80101c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -152,17 +152,6 @@ struct page {
 		struct page *first_page;	/* Compound tail pages */
 	};
 
-#ifdef CONFIG_AUTONUMA
-	/*
-	 * FIXME: move to pgdat section along with the memcg and allocate
-	 * at runtime only in presence of a numa system.
-	 */
-#if MAX_NUMNODES > 32767
-#error "too many nodes"
-#endif
-	short autonuma_last_nid;
-#endif
-
 	/*
 	 * On machines where all RAM is mapped into kernel address space,
 	 * we can simply calculate the virtual address. On machines with
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f793541..db68389 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -710,6 +710,9 @@ typedef struct pglist_data {
 	int kswapd_max_order;
 	enum zone_type classzone_idx;
 #ifdef CONFIG_AUTONUMA
+#if !defined(CONFIG_SPARSEMEM)
+	struct page_autonuma *node_page_autonuma;
+#endif
 	/*
 	 * Lock serializing the per destination node AutoNUMA memory
 	 * migration rate limiting data.
@@ -1081,6 +1084,15 @@ struct mem_section {
 	 * section. (see memcontrol.h/page_cgroup.h about this.)
 	 */
 	struct page_cgroup *page_cgroup;
+#endif
+#ifdef CONFIG_AUTONUMA
+	/*
+	 * If !SPARSEMEM, pgdat doesn't have page_autonuma pointer. We use
+	 * section.
+	 */
+	struct page_autonuma *section_page_autonuma;
+#endif
+#if defined(CONFIG_MEMCG) ^ defined(CONFIG_AUTONUMA)
 	unsigned long pad;
 #endif
 };
diff --git a/include/linux/page_autonuma.h b/include/linux/page_autonuma.h
new file mode 100644
index 0000000..6da6c51
--- /dev/null
+++ b/include/linux/page_autonuma.h
@@ -0,0 +1,50 @@
+#ifndef _LINUX_PAGE_AUTONUMA_H
+#define _LINUX_PAGE_AUTONUMA_H
+
+#include <linux/autonuma_flags.h>
+
+#if defined(CONFIG_AUTONUMA) && !defined(CONFIG_SPARSEMEM)
+extern void __init page_autonuma_init_flatmem(void);
+#else
+static inline void __init page_autonuma_init_flatmem(void) {}
+#endif
+
+#ifdef CONFIG_AUTONUMA
+
+extern void __meminit page_autonuma_map_init(struct page *page,
+					     struct page_autonuma *page_autonuma,
+					     int nr_pages);
+
+#ifdef CONFIG_SPARSEMEM
+#define PAGE_AUTONUMA_SIZE (sizeof(struct page_autonuma))
+#define SECTION_PAGE_AUTONUMA_SIZE (PAGE_AUTONUMA_SIZE *	\
+				    PAGES_PER_SECTION)
+#endif
+
+extern void __meminit pgdat_autonuma_init(struct pglist_data *);
+
+#else /* CONFIG_AUTONUMA */
+
+#ifdef CONFIG_SPARSEMEM
+struct page_autonuma;
+#define PAGE_AUTONUMA_SIZE 0
+#define SECTION_PAGE_AUTONUMA_SIZE 0
+#endif /* CONFIG_SPARSEMEM */
+
+static inline void pgdat_autonuma_init(struct pglist_data *pgdat) {}
+
+#endif /* CONFIG_AUTONUMA */
+
+#ifdef CONFIG_SPARSEMEM
+extern struct page_autonuma * __meminit __kmalloc_section_page_autonuma(int nid,
+									unsigned long nr_pages);
+extern void __kfree_section_page_autonuma(struct page_autonuma *page_autonuma,
+					  unsigned long nr_pages);
+extern void __init sparse_early_page_autonuma_alloc_node(struct page_autonuma **page_autonuma_map,
+							 unsigned long pnum_begin,
+							 unsigned long pnum_end,
+							 unsigned long map_count,
+							 int nodeid);
+#endif
+
+#endif /* _LINUX_PAGE_AUTONUMA_H */
diff --git a/init/main.c b/init/main.c
index b286730..586764f 100644
--- a/init/main.c
+++ b/init/main.c
@@ -69,6 +69,7 @@
 #include <linux/slab.h>
 #include <linux/perf_event.h>
 #include <linux/file.h>
+#include <linux/page_autonuma.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -456,6 +457,7 @@ static void __init mm_init(void)
 	 * bigger than MAX_ORDER unless SPARSEMEM.
 	 */
 	page_cgroup_init_flatmem();
+	page_autonuma_init_flatmem();
 	mem_init();
 	kmem_cache_init();
 	percpu_init_late();
diff --git a/mm/Makefile b/mm/Makefile
index 0fd3165..5a4fa30 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -34,7 +34,7 @@ obj-$(CONFIG_FRONTSWAP)	+= frontswap.o
 obj-$(CONFIG_HAS_DMA)	+= dmapool.o
 obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
 obj-$(CONFIG_NUMA) 	+= mempolicy.o
-obj-$(CONFIG_AUTONUMA) 	+= autonuma.o
+obj-$(CONFIG_AUTONUMA) 	+= autonuma.o page_autonuma.o
 obj-$(CONFIG_SPARSEMEM)	+= sparse.o
 obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
 obj-$(CONFIG_SLOB) += slob.o
diff --git a/mm/autonuma.c b/mm/autonuma.c
index 1b2530c..b5c5ff6 100644
--- a/mm/autonuma.c
+++ b/mm/autonuma.c
@@ -55,10 +55,19 @@ void autonuma_migrate_split_huge_page(struct page *page,
 				      struct page *page_tail)
 {
 	int last_nid;
+	struct page_autonuma *page_autonuma, *page_tail_autonuma;
 
-	last_nid = ACCESS_ONCE(page->autonuma_last_nid);
+	if (!autonuma_possible())
+		return;
+
+	page_autonuma = lookup_page_autonuma(page);
+	page_tail_autonuma = lookup_page_autonuma(page_tail);
+
+	VM_BUG_ON(page_tail_autonuma->autonuma_last_nid != -1);
+
+	last_nid = ACCESS_ONCE(page_autonuma->autonuma_last_nid);
 	if (last_nid >= 0)
-		page_tail->autonuma_last_nid = last_nid;
+		page_tail_autonuma->autonuma_last_nid = last_nid;
 }
 
 static int sync_isolate_migratepages(struct list_head *migratepages,
@@ -176,13 +185,18 @@ static struct page *alloc_migrate_dst_page(struct page *page,
 {
 	int nid = (int) data;
 	struct page *newpage;
+	struct page_autonuma *page_autonuma, *newpage_autonuma;
 	newpage = alloc_pages_exact_node(nid,
 					 (GFP_HIGHUSER_MOVABLE | GFP_THISNODE |
 					  __GFP_NOMEMALLOC | __GFP_NORETRY |
 					  __GFP_NOWARN | __GFP_NO_KSWAPD) &
 					 ~GFP_IOFS, 0);
-	if (newpage)
-		newpage->autonuma_last_nid = page->autonuma_last_nid;
+	if (newpage) {
+		page_autonuma = lookup_page_autonuma(page);
+		newpage_autonuma = lookup_page_autonuma(newpage);
+		newpage_autonuma->autonuma_last_nid =
+			page_autonuma->autonuma_last_nid;
+	}
 	return newpage;
 }
 
@@ -291,13 +305,14 @@ static void numa_hinting_fault_cpu_follow_memory(struct task_struct *p,
 static inline bool last_nid_set(struct page *page, int this_nid)
 {
 	bool ret = true;
-	int autonuma_last_nid = ACCESS_ONCE(page->autonuma_last_nid);
+	struct page_autonuma *page_autonuma = lookup_page_autonuma(page);
+	int autonuma_last_nid = ACCESS_ONCE(page_autonuma->autonuma_last_nid);
 	VM_BUG_ON(this_nid < 0);
 	VM_BUG_ON(this_nid >= MAX_NUMNODES);
 	if (autonuma_last_nid != this_nid) {
 		if (autonuma_last_nid >= 0)
 			ret = false;
-		ACCESS_ONCE(page->autonuma_last_nid) = this_nid;
+		ACCESS_ONCE(page_autonuma->autonuma_last_nid) = this_nid;
 	}
 	return ret;
 }
@@ -1185,7 +1200,8 @@ static int __init noautonuma_setup(char *str)
 	}
 	return 1;
 }
-__setup("noautonuma", noautonuma_setup);
+/* early so sparse.c also can see it */
+early_param("noautonuma", noautonuma_setup);
 
 static bool autonuma_init_checks_failed(void)
 {
@@ -1209,7 +1225,12 @@ static int __init autonuma_init(void)
 
 	VM_BUG_ON(num_possible_nodes() < 1);
 	if (num_possible_nodes() <= 1 || !autonuma_possible()) {
-		clear_bit(AUTONUMA_POSSIBLE_FLAG, &autonuma_flags);
+		/* should have been already initialized by page_autonuma */
+		if (autonuma_possible()) {
+			WARN_ON(1);
+			/* try to fixup if it wasn't ok */
+			clear_bit(AUTONUMA_POSSIBLE_FLAG, &autonuma_flags);
+		}
 		return -EINVAL;
 	} else if (autonuma_init_checks_failed()) {
 		printk("autonuma disengaged: init checks failed\n");
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 757c1cc..86db742 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1850,7 +1850,12 @@ static bool __collapse_huge_page_copy(pte_t *pte, struct page *page,
 	bool mknuma = false;
 #ifdef CONFIG_AUTONUMA
 	int autonuma_last_nid = -1;
+	struct page_autonuma *src_page_an, *page_an = NULL;
+
+	if (autonuma_possible())
+		page_an = lookup_page_autonuma(page);
 #endif
+
 	for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
 		pte_t pteval = *_pte;
 		struct page *src_page;
@@ -1862,12 +1867,12 @@ static bool __collapse_huge_page_copy(pte_t *pte, struct page *page,
 			src_page = pte_page(pteval);
 #ifdef CONFIG_AUTONUMA
 			/* pick the first one, better than nothing */
-			if (autonuma_last_nid < 0) {
+			if (autonuma_possible() && autonuma_last_nid < 0) {
+				src_page_an = lookup_page_autonuma(src_page);
 				autonuma_last_nid =
-					ACCESS_ONCE(src_page->
-						    autonuma_last_nid);
+					ACCESS_ONCE(src_page_an->autonuma_last_nid);
 				if (autonuma_last_nid >= 0)
-					ACCESS_ONCE(page->autonuma_last_nid) =
+					ACCESS_ONCE(page_an->autonuma_last_nid) =
 						autonuma_last_nid;
 			}
 #endif
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e096742..8e6493a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -59,6 +59,7 @@
 #include <linux/migrate.h>
 #include <linux/page-debug-flags.h>
 #include <linux/autonuma.h>
+#include <linux/page_autonuma.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -619,9 +620,7 @@ static inline int free_pages_check(struct page *page)
 		bad_page(page);
 		return 1;
 	}
-#ifdef CONFIG_AUTONUMA
-	page->autonuma_last_nid = -1;
-#endif
+	autonuma_free_page(page);
 	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
 		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
 	return 0;
@@ -3797,9 +3796,6 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
 
 		INIT_LIST_HEAD(&page->lru);
-#ifdef CONFIG_AUTONUMA
-		page->autonuma_last_nid = -1;
-#endif
 #ifdef WANT_PAGE_VIRTUAL
 		/* The shift won't overflow because ZONE_NORMAL is below 4G. */
 		if (!is_highmem_idx(zone))
@@ -4402,14 +4398,10 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
 	int ret;
 
 	pgdat_resize_init(pgdat);
-#ifdef CONFIG_AUTONUMA
-	spin_lock_init(&pgdat->autonuma_migrate_lock);
-	pgdat->autonuma_migrate_nr_pages = 0;
-	pgdat->autonuma_migrate_last_jiffies = jiffies;
-#endif
 	init_waitqueue_head(&pgdat->kswapd_wait);
 	init_waitqueue_head(&pgdat->pfmemalloc_wait);
 	pgdat_page_cgroup_init(pgdat);
+	pgdat_autonuma_init(pgdat);
 
 	for (j = 0; j < MAX_NR_ZONES; j++) {
 		struct zone *zone = pgdat->node_zones + j;
diff --git a/mm/page_autonuma.c b/mm/page_autonuma.c
new file mode 100644
index 0000000..d400d7f
--- /dev/null
+++ b/mm/page_autonuma.c
@@ -0,0 +1,237 @@
+#include <linux/mm.h>
+#include <linux/memory.h>
+#include <linux/autonuma.h>
+#include <linux/page_autonuma.h>
+#include <linux/bootmem.h>
+#include <linux/vmalloc.h>
+
+void __meminit page_autonuma_map_init(struct page *page,
+				      struct page_autonuma *page_autonuma,
+				      int nr_pages)
+{
+	struct page *end;
+	for (end = page + nr_pages; page < end; page++, page_autonuma++)
+		page_autonuma->autonuma_last_nid = -1;
+}
+
+static void __meminit __pgdat_autonuma_init(struct pglist_data *pgdat)
+{
+	spin_lock_init(&pgdat->autonuma_migrate_lock);
+	pgdat->autonuma_migrate_nr_pages = 0;
+	pgdat->autonuma_migrate_last_jiffies = jiffies;
+
+	/* initialize autonuma_possible() */
+	if (num_possible_nodes() <= 1)
+		clear_bit(AUTONUMA_POSSIBLE_FLAG, &autonuma_flags);
+}
+
+#if !defined(CONFIG_SPARSEMEM)
+
+static unsigned long total_usage;
+
+void __meminit pgdat_autonuma_init(struct pglist_data *pgdat)
+{
+	__pgdat_autonuma_init(pgdat);
+	pgdat->node_page_autonuma = NULL;
+}
+
+struct page_autonuma *lookup_page_autonuma(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long offset;
+	struct page_autonuma *base;
+
+	base = NODE_DATA(page_to_nid(page))->node_page_autonuma;
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * The sanity checks the page allocator does upon freeing a
+	 * page can reach here before the page_autonuma arrays are
+	 * allocated when feeding a range of pages to the allocator
+	 * for the first time during bootup or memory hotplug.
+	 */
+	if (unlikely(!base))
+		return NULL;
+#endif
+	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
+	return base + offset;
+}
+
+static int __init alloc_node_page_autonuma(int nid)
+{
+	struct page_autonuma *base;
+	unsigned long table_size;
+	unsigned long nr_pages;
+
+	nr_pages = NODE_DATA(nid)->node_spanned_pages;
+	if (!nr_pages)
+		return 0;
+
+	table_size = sizeof(struct page_autonuma) * nr_pages;
+
+	base = __alloc_bootmem_node_nopanic(NODE_DATA(nid),
+			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+	if (!base)
+		return -ENOMEM;
+	NODE_DATA(nid)->node_page_autonuma = base;
+	total_usage += table_size;
+	page_autonuma_map_init(NODE_DATA(nid)->node_mem_map, base, nr_pages);
+	return 0;
+}
+
+void __init page_autonuma_init_flatmem(void)
+{
+
+	int nid, fail;
+
+	/* __pgdat_autonuma_init initialized autonuma_possible() */
+	if (!autonuma_possible())
+		return;
+
+	for_each_online_node(nid)  {
+		fail = alloc_node_page_autonuma(nid);
+		if (fail)
+			goto fail;
+	}
+	printk(KERN_INFO "allocated %lu KBytes of page_autonuma\n",
+	       total_usage >> 10);
+	printk(KERN_INFO "please try the 'noautonuma' option if you"
+	" don't want to allocate page_autonuma memory\n");
+	return;
+fail:
+	printk(KERN_CRIT "allocation of page_autonuma failed.\n");
+	printk(KERN_CRIT "please try the 'noautonuma' boot option\n");
+	panic("Out of memory");
+}
+
+#else /* CONFIG_SPARSEMEM */
+
+struct page_autonuma *lookup_page_autonuma(struct page *page)
+{
+	unsigned long pfn = page_to_pfn(page);
+	struct mem_section *section = __pfn_to_section(pfn);
+
+	/* if it's not a power of two we may be wasting memory */
+	BUILD_BUG_ON(SECTION_PAGE_AUTONUMA_SIZE &
+		     (SECTION_PAGE_AUTONUMA_SIZE-1));
+
+	/* memsection must be a power of two */
+	BUILD_BUG_ON(sizeof(struct mem_section) &
+		     (sizeof(struct mem_section)-1));
+
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * The sanity checks the page allocator does upon freeing a
+	 * page can reach here before the page_autonuma arrays are
+	 * allocated when feeding a range of pages to the allocator
+	 * for the first time during bootup or memory hotplug.
+	 */
+	if (!section->section_page_autonuma)
+		return NULL;
+#endif
+	return section->section_page_autonuma + pfn;
+}
+
+void __meminit pgdat_autonuma_init(struct pglist_data *pgdat)
+{
+	__pgdat_autonuma_init(pgdat);
+}
+
+struct page_autonuma * __meminit __kmalloc_section_page_autonuma(int nid,
+								 unsigned long nr_pages)
+{
+	struct page_autonuma *ret;
+	struct page *page;
+	unsigned long memmap_size = PAGE_AUTONUMA_SIZE * nr_pages;
+
+	page = alloc_pages_node(nid, GFP_KERNEL|__GFP_NOWARN,
+				get_order(memmap_size));
+	if (page)
+		goto got_map_page_autonuma;
+
+	ret = vmalloc(memmap_size);
+	if (ret)
+		goto out;
+
+	return NULL;
+got_map_page_autonuma:
+	ret = (struct page_autonuma *)pfn_to_kaddr(page_to_pfn(page));
+out:
+	return ret;
+}
+
+void __kfree_section_page_autonuma(struct page_autonuma *page_autonuma,
+				   unsigned long nr_pages)
+{
+	if (is_vmalloc_addr(page_autonuma))
+		vfree(page_autonuma);
+	else
+		free_pages((unsigned long)page_autonuma,
+			   get_order(PAGE_AUTONUMA_SIZE * nr_pages));
+}
+
+static struct page_autonuma __init *sparse_page_autonuma_map_populate(unsigned long pnum,
+								      int nid)
+{
+	struct page_autonuma *map;
+	unsigned long size;
+
+	map = alloc_remap(nid, SECTION_PAGE_AUTONUMA_SIZE);
+	if (map)
+		return map;
+
+	size = PAGE_ALIGN(SECTION_PAGE_AUTONUMA_SIZE);
+	map = __alloc_bootmem_node_high(NODE_DATA(nid), size,
+					PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+	return map;
+}
+
+void __init sparse_early_page_autonuma_alloc_node(struct page_autonuma **page_autonuma_map,
+						  unsigned long pnum_begin,
+						  unsigned long pnum_end,
+						  unsigned long map_count,
+						  int nodeid)
+{
+	void *map;
+	unsigned long pnum;
+	unsigned long size = SECTION_PAGE_AUTONUMA_SIZE;
+
+	map = alloc_remap(nodeid, size * map_count);
+	if (map) {
+		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+			if (!present_section_nr(pnum))
+				continue;
+			page_autonuma_map[pnum] = map;
+			map += size;
+		}
+		return;
+	}
+
+	size = PAGE_ALIGN(size);
+	map = __alloc_bootmem_node_high(NODE_DATA(nodeid), size * map_count,
+					PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
+	if (map) {
+		for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+			if (!present_section_nr(pnum))
+				continue;
+			page_autonuma_map[pnum] = map;
+			map += size;
+		}
+		return;
+	}
+
+	/* fallback */
+	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
+		struct mem_section *ms;
+
+		if (!present_section_nr(pnum))
+			continue;
+		page_autonuma_map[pnum] = sparse_page_autonuma_map_populate(pnum, nodeid);
+		if (page_autonuma_map[pnum])
+			continue;
+		ms = __nr_to_section(pnum);
+		printk(KERN_ERR "%s: sparsemem page_autonuma map backing failed "
+		       "some memory will not be available.\n", __func__);
+	}
+}
+
+#endif /* CONFIG_SPARSEMEM */
diff --git a/mm/sparse.c b/mm/sparse.c
index fac95f2..5b8d018 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -9,6 +9,7 @@
 #include <linux/export.h>
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
+#include <linux/page_autonuma.h>
 #include "internal.h"
 #include <asm/dma.h>
 #include <asm/pgalloc.h>
@@ -230,7 +231,8 @@ struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pn
 
 static int __meminit sparse_init_one_section(struct mem_section *ms,
 		unsigned long pnum, struct page *mem_map,
-		unsigned long *pageblock_bitmap)
+		unsigned long *pageblock_bitmap,
+		struct page_autonuma *page_autonuma)
 {
 	if (!present_section(ms))
 		return -EINVAL;
@@ -239,6 +241,14 @@ static int __meminit sparse_init_one_section(struct mem_section *ms,
 	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
 							SECTION_HAS_MEM_MAP;
  	ms->pageblock_flags = pageblock_bitmap;
+#ifdef CONFIG_AUTONUMA
+	if (page_autonuma) {
+		ms->section_page_autonuma = page_autonuma - section_nr_to_pfn(pnum);
+		page_autonuma_map_init(mem_map, page_autonuma, PAGES_PER_SECTION);
+	}
+#else
+	BUG_ON(page_autonuma);
+#endif
 
 	return 1;
 }
@@ -480,6 +490,9 @@ void __init sparse_init(void)
 	int size2;
 	struct page **map_map;
 #endif
+	struct page_autonuma **uninitialized_var(page_autonuma_map);
+	struct page_autonuma *page_autonuma;
+	int size3;
 
 	/* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
 	set_pageblock_order();
@@ -577,6 +590,63 @@ void __init sparse_init(void)
 					 map_count, nodeid_begin);
 #endif
 
+	/* __pgdat_autonuma_init initialized autonuma_possible() */
+	if (autonuma_possible()) {
+		unsigned long total_page_autonuma;
+		unsigned long page_autonuma_count;
+
+		size3 = sizeof(struct page_autonuma *) * NR_MEM_SECTIONS;
+		page_autonuma_map = alloc_bootmem(size3);
+		if (!page_autonuma_map)
+			panic("can not allocate page_autonuma_map\n");
+
+		for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
+			struct mem_section *ms;
+
+			if (!present_section_nr(pnum))
+				continue;
+			ms = __nr_to_section(pnum);
+			nodeid_begin = sparse_early_nid(ms);
+			pnum_begin = pnum;
+			break;
+		}
+		total_page_autonuma = 0;
+		page_autonuma_count = 1;
+		for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) {
+			struct mem_section *ms;
+			int nodeid;
+
+			if (!present_section_nr(pnum))
+				continue;
+			ms = __nr_to_section(pnum);
+			nodeid = sparse_early_nid(ms);
+			if (nodeid == nodeid_begin) {
+				page_autonuma_count++;
+				continue;
+			}
+			/* ok, we need to take cake of from pnum_begin to pnum - 1*/
+			sparse_early_page_autonuma_alloc_node(page_autonuma_map,
+							      pnum_begin,
+							      NR_MEM_SECTIONS,
+							      page_autonuma_count,
+							      nodeid_begin);
+			total_page_autonuma += SECTION_PAGE_AUTONUMA_SIZE * page_autonuma_count;
+			/* new start, update count etc*/
+			nodeid_begin = nodeid;
+			pnum_begin = pnum;
+			page_autonuma_count = 1;
+		}
+		/* ok, last chunk */
+		sparse_early_page_autonuma_alloc_node(page_autonuma_map, pnum_begin,
+						      NR_MEM_SECTIONS,
+						      page_autonuma_count, nodeid_begin);
+		total_page_autonuma += SECTION_PAGE_AUTONUMA_SIZE * page_autonuma_count;
+		printk("allocated %lu KBytes of page_autonuma\n",
+		       total_page_autonuma >> 10);
+		printk(KERN_INFO "please try the 'noautonuma' option if you"
+		       " don't want to allocate page_autonuma memory\n");
+	}
+
 	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
 		if (!present_section_nr(pnum))
 			continue;
@@ -585,6 +655,13 @@ void __init sparse_init(void)
 		if (!usemap)
 			continue;
 
+		if (autonuma_possible()) {
+			page_autonuma = page_autonuma_map[pnum];
+			if (!page_autonuma)
+				continue;
+		} else
+			page_autonuma = NULL;
+
 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 		map = map_map[pnum];
 #else
@@ -594,11 +671,13 @@ void __init sparse_init(void)
 			continue;
 
 		sparse_init_one_section(__nr_to_section(pnum), pnum, map,
-								usemap);
+					usemap, page_autonuma);
 	}
 
 	vmemmap_populate_print_last();
 
+	if (autonuma_possible())
+		free_bootmem(__pa(page_autonuma_map), size3);
 #ifdef CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER
 	free_bootmem(__pa(map_map), size2);
 #endif
@@ -685,7 +764,8 @@ static void free_map_bootmem(struct page *page, unsigned long nr_pages)
 }
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
-static void free_section_usemap(struct page *memmap, unsigned long *usemap)
+static void free_section_usemap(struct page *memmap, unsigned long *usemap,
+				struct page_autonuma *page_autonuma)
 {
 	struct page *usemap_page;
 	unsigned long nr_pages;
@@ -699,8 +779,14 @@ static void free_section_usemap(struct page *memmap, unsigned long *usemap)
 	 */
 	if (PageSlab(usemap_page)) {
 		kfree(usemap);
-		if (memmap)
+		if (memmap) {
 			__kfree_section_memmap(memmap, PAGES_PER_SECTION);
+			if (autonuma_possible())
+				__kfree_section_page_autonuma(page_autonuma,
+							      PAGES_PER_SECTION);
+			else
+				BUG_ON(page_autonuma);
+		}
 		return;
 	}
 
@@ -717,6 +803,13 @@ static void free_section_usemap(struct page *memmap, unsigned long *usemap)
 			>> PAGE_SHIFT;
 
 		free_map_bootmem(memmap_page, nr_pages);
+
+		if (autonuma_possible()) {
+			struct page *page_autonuma_page;
+			page_autonuma_page = virt_to_page(page_autonuma);
+			free_map_bootmem(page_autonuma_page, nr_pages);
+		} else
+			BUG_ON(page_autonuma);
 	}
 }
 
@@ -732,6 +825,7 @@ int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
 	struct pglist_data *pgdat = zone->zone_pgdat;
 	struct mem_section *ms;
 	struct page *memmap;
+	struct page_autonuma *page_autonuma;
 	unsigned long *usemap;
 	unsigned long flags;
 	int ret;
@@ -751,6 +845,16 @@ int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
 		__kfree_section_memmap(memmap, nr_pages);
 		return -ENOMEM;
 	}
+	if (autonuma_possible()) {
+		page_autonuma = __kmalloc_section_page_autonuma(pgdat->node_id,
+								nr_pages);
+		if (!page_autonuma) {
+			kfree(usemap);
+			__kfree_section_memmap(memmap, nr_pages);
+			return -ENOMEM;
+		}
+	} else
+		page_autonuma = NULL;
 
 	pgdat_resize_lock(pgdat, &flags);
 
@@ -762,11 +866,16 @@ int __meminit sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
 
 	ms->section_mem_map |= SECTION_MARKED_PRESENT;
 
-	ret = sparse_init_one_section(ms, section_nr, memmap, usemap);
+	ret = sparse_init_one_section(ms, section_nr, memmap, usemap,
+				      page_autonuma);
 
 out:
 	pgdat_resize_unlock(pgdat, &flags);
 	if (ret <= 0) {
+		if (autonuma_possible())
+			__kfree_section_page_autonuma(page_autonuma, nr_pages);
+		else
+			BUG_ON(page_autonuma);
 		kfree(usemap);
 		__kfree_section_memmap(memmap, nr_pages);
 	}
@@ -777,6 +886,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 {
 	struct page *memmap = NULL;
 	unsigned long *usemap = NULL;
+	struct page_autonuma *page_autonuma = NULL;
 
 	if (ms->section_mem_map) {
 		usemap = ms->pageblock_flags;
@@ -784,8 +894,12 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 						__section_nr(ms));
 		ms->section_mem_map = 0;
 		ms->pageblock_flags = NULL;
+
+#ifdef CONFIG_AUTONUMA
+		page_autonuma = ms->section_page_autonuma;
+#endif
 	}
 
-	free_section_usemap(memmap, usemap);
+	free_section_usemap(memmap, usemap, page_autonuma);
 }
 #endif

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Re: [PATCH 29/33] autonuma: page_autonuma

[Christoph Lameter]

On Thu, 4 Oct 2012, Andrea Arcangeli wrote:

> Move the autonuma_last_nid from the "struct page" to a separate
> page_autonuma data structure allocated in the memsection (with
> sparsemem) or in the pgdat (with flatmem).

Note that there is a available word in struct page before the autonuma
patches on x86_64 with CONFIG_HAVE_ALIGNED_STRUCT_PAGE.

In fact the page_autonuma fills up the structure to nicely fit in one 64
byte cacheline.

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(no subject)

[Andrea Arcangeli]

Subject: Re: [PATCH 29/33] autonuma: page_autonuma
Reply-To: 
In-Reply-To: <0000013a2c223da2-632aa43e-21f8-4abd-a0ba-2e1b49881e3a-000000@email.amazonses.com>

Hi Christoph,

On Thu, Oct 04, 2012 at 02:16:14PM +0000, Christoph Lameter wrote:
> On Thu, 4 Oct 2012, Andrea Arcangeli wrote:
> 
> > Move the autonuma_last_nid from the "struct page" to a separate
> > page_autonuma data structure allocated in the memsection (with
> > sparsemem) or in the pgdat (with flatmem).
> 
> Note that there is a available word in struct page before the autonuma
> patches on x86_64 with CONFIG_HAVE_ALIGNED_STRUCT_PAGE.
> 
> In fact the page_autonuma fills up the structure to nicely fit in one 64
> byte cacheline.

Good point indeed.

So we could drop page_autonuma by creating a CONFIG_SLUB=y dependency
(AUTONUMA wouldn't be available in the kernel config if SLAB=y, and it
also wouldn't be available on 32bit archs but the latter isn't a
problem).

I think it's a reasonable alternative to page_autonuma. Certainly it
looks more appealing than taking over 16 precious bits from
page->flags. There are still pros and cons. I'm neutral on it so more
comments would be welcome ;).

Andrea

PS. randomly moved some in Cc over to Bcc as I overflowed the max
header allowed on linux-kernel oops!

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Re: your mail

[Christoph Lameter]

On Thu, 4 Oct 2012, Andrea Arcangeli wrote:

> So we could drop page_autonuma by creating a CONFIG_SLUB=y dependency
> (AUTONUMA wouldn't be available in the kernel config if SLAB=y, and it
> also wouldn't be available on 32bit archs but the latter isn't a
> problem).

Nope it should depend on page struct alignment. Other kernel subsystems
may be depeding on page struct alignment in the future (and some other
arches may already have that requirement)

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Re: [PATCH 29/33] autonuma: page_autonuma

[Andrea Arcangeli]

Hi Christoph,

On Thu, Oct 04, 2012 at 06:17:37PM +0000, Christoph Lameter wrote:
> On Thu, 4 Oct 2012, Andrea Arcangeli wrote:
> 
> > So we could drop page_autonuma by creating a CONFIG_SLUB=y dependency
> > (AUTONUMA wouldn't be available in the kernel config if SLAB=y, and it
> > also wouldn't be available on 32bit archs but the latter isn't a
> > problem).
> 
> Nope it should depend on page struct alignment. Other kernel subsystems
> may be depeding on page struct alignment in the future (and some other
> arches may already have that requirement)

But currently only SLUB x86 64bit selects
CONFIG_HAVE_ALIGNED_STRUCT_PAGE:

arch/Kconfig:config HAVE_ALIGNED_STRUCT_PAGE
arch/x86/Kconfig:       select HAVE_ALIGNED_STRUCT_PAGE if SLUB && !M386
include/linux/mm_types.h:       defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
include/linux/mm_types.h:#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
mm/slub.c:    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
mm/slub.c:    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
mm/slub.c:    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)

So in practice a dependency on CONFIG_HAVE_ALIGNED_STRUCT_PAGE would
still mean the same: only available when SLUB enables it, and only on
x86 64bit (ppc64?).

If you mean CONFIG_AUTONUMA=y should select (not depend) on
CONFIG_HAVE_ALIGNED_STRUCT_PAGE, that would allow to enable it in all
.configs but it would have a worse cons: losing 8bytes per page
unconditionally (even when booting on non-NUMA hardware).

The current page_autonuma solution is substantially memory-cheaper
than selecting CONFIG_HAVE_ALIGNED_STRUCT_PAGE: it allocates 2bytes
per page at boot time but only if booting on real NUMA hardware
(without altering the page structure). So to me it looks still quite a
decent tradeoff.

Thanks,
Andrea

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Re: [PATCH 29/33] autonuma: page_autonuma

[Christoph Lameter]

On Thu, 4 Oct 2012, Andrea Arcangeli wrote:

> If you mean CONFIG_AUTONUMA=y should select (not depend) on
> CONFIG_HAVE_ALIGNED_STRUCT_PAGE, that would allow to enable it in all
> .configs but it would have a worse cons: losing 8bytes per page
> unconditionally (even when booting on non-NUMA hardware).

I did not say anything like that. Still not convinced that autonuma is
worth doing and that it is beneficial given the complexity it adds to the
kernel. Just wanted to point out that there is a case to be made for
adding another word to the page struct.

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Re: [PATCH 29/33] autonuma: page_autonuma

[KOSAKI Motohiro]

> +struct page_autonuma *lookup_page_autonuma(struct page *page)
> +{
> +	unsigned long pfn = page_to_pfn(page);
> +	unsigned long offset;
> +	struct page_autonuma *base;
> +
> +	base = NODE_DATA(page_to_nid(page))->node_page_autonuma;
> +#ifdef CONFIG_DEBUG_VM
> +	/*
> +	 * The sanity checks the page allocator does upon freeing a
> +	 * page can reach here before the page_autonuma arrays are
> +	 * allocated when feeding a range of pages to the allocator
> +	 * for the first time during bootup or memory hotplug.
> +	 */
> +	if (unlikely(!base))
> +		return NULL;
> +#endif

When using CONFIG_DEBUG_VM, please just use BUG_ON instead of additional
sanity check. Otherwise only MM people might fault to find a real bug.


And I have additional question here. What's happen if memory hotplug occur
and several autonuma_last_nid will point to invalid node id? My quick skimming
didn't find hotplug callback code.


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Re: [PATCH 29/33] autonuma: page_autonuma

[Andrea Arcangeli]

Hi Christoph,

On Thu, Oct 04, 2012 at 07:11:51PM +0000, Christoph Lameter wrote:
> I did not say anything like that. Still not convinced that autonuma is
> worth doing and that it is beneficial given the complexity it adds to the
> kernel. Just wanted to point out that there is a case to be made for
> adding another word to the page struct.

You've seen the benchmarks, no other solution that exists today solves
all those cases and never showed a regression compared to
upstream. Running that much faster is very beneficial in my
view.

Expecting the admin of a 2 socket system to use hard bindings manually
is unrealistic, even for a 4 socket is unrealistic.

If you've 512 node system well then you can afford to setup everything
manually and boot with noautonuma, no argument about that.

About the complexity, well there's no simple solution to an hard
problem. The proof comes from the schednuma crowd that is currently
copying the AutoNUMA scheduler cpu-follow-memory design at full force
as we speak.

Thanks,
Andrea

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Re: [PATCH 29/33] autonuma: page_autonuma

[Andrea Arcangeli]

Hi KOSAKI,

On Thu, Oct 04, 2012 at 04:09:40PM -0400, KOSAKI Motohiro wrote:
> > +struct page_autonuma *lookup_page_autonuma(struct page *page)
> > +{
> > +	unsigned long pfn = page_to_pfn(page);
> > +	unsigned long offset;
> > +	struct page_autonuma *base;
> > +
> > +	base = NODE_DATA(page_to_nid(page))->node_page_autonuma;
> > +#ifdef CONFIG_DEBUG_VM
> > +	/*
> > +	 * The sanity checks the page allocator does upon freeing a
> > +	 * page can reach here before the page_autonuma arrays are
> > +	 * allocated when feeding a range of pages to the allocator
> > +	 * for the first time during bootup or memory hotplug.
> > +	 */
> > +	if (unlikely(!base))
> > +		return NULL;
> > +#endif
> 
> When using CONFIG_DEBUG_VM, please just use BUG_ON instead of additional
> sanity check. Otherwise only MM people might fault to find a real bug.

Agreed. But I just tried to stick to the page_cgroup.c model. I
suggest you send a patch to fix it in mm/page_cgroup.c, then I'll
synchronize mm/page_autonuma.c with whatever lands in page_cgroup.c.

The idea is that in the future it'd be nice to unify those with a
common implementation. And the closer page_cgroup.c and
page_autonuma.c are, the less work it'll be to update them to use a
common framework. And if it's never going to be worth it to unify it
(if it generates more code than it saves), well then keeping the code
as similar as possible, is still beneficial so it's easier to review both.

> And I have additional question here. What's happen if memory hotplug occur
> and several autonuma_last_nid will point to invalid node id? My quick skimming
> didn't find hotplug callback code.

last_nid is statistical info so if it's random it's ok (I didn't add
bugchecks to trap uninitialized cases to it, maybe I should?).

sparse_init_one_section also initializes it, and that's invoked by
sparse_add_one_section.

Also those fields are also initialized when the page is freed the
first time to add it to the buddy, but I didn't want to depend on
that, I thought an explicit init post-allocation would be more robust.

By reviewing it the only thing I found is that I was wasting a bit of
.text for 32bit builds (CONFIG_SPARSEMEM=n).

diff --git a/mm/page_autonuma.c b/mm/page_autonuma.c
index d400d7f..303b427 100644
--- a/mm/page_autonuma.c
+++ b/mm/page_autonuma.c
@@ -14,7 +14,7 @@ void __meminit page_autonuma_map_init(struct page *page,
 		page_autonuma->autonuma_last_nid = -1;
 }
 
-static void __meminit __pgdat_autonuma_init(struct pglist_data *pgdat)
+static void __paginginit __pgdat_autonuma_init(struct pglist_data *pgdat)
 {
 	spin_lock_init(&pgdat->autonuma_migrate_lock);
 	pgdat->autonuma_migrate_nr_pages = 0;
@@ -29,7 +29,7 @@ static void __meminit __pgdat_autonuma_init(struct pglist_data *pgdat)
 
 static unsigned long total_usage;
 
-void __meminit pgdat_autonuma_init(struct pglist_data *pgdat)
+void __paginginit pgdat_autonuma_init(struct pglist_data *pgdat)
 {
 	__pgdat_autonuma_init(pgdat);
 	pgdat->node_page_autonuma = NULL;
@@ -131,7 +131,7 @@ struct page_autonuma *lookup_page_autonuma(struct page *page)
 	return section->section_page_autonuma + pfn;
 }
 
-void __meminit pgdat_autonuma_init(struct pglist_data *pgdat)
+void __paginginit pgdat_autonuma_init(struct pglist_data *pgdat)
 {
 	__pgdat_autonuma_init(pgdat);
 }


So those can be freed if it's a non sparsemem build. The caller has
__paginging init too so it should be ok.


The other page_autonuma.c places invoked only by sparsemem hotplug
code are using meminit so in theory it should work (I haven't tested
it yet).

Thanks for the review!
Andrea

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