[PATCH 4/8] sched, numa, mm: Add last_cpu to page flags
From: Peter Zijlstra
Date: Mon Nov 12 2012 - 11:23:27 EST
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_SCHED_NUMA 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@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/mm.h | 90 ++++++++++++++++++++------------------
include/linux/mm_types.h | 9 +++
include/linux/mmzone.h | 14 -----
include/linux/page-flags-layout.h | 83 +++++++++++++++++++++++++++++++++++
kernel/bounds.c | 2
mm/huge_memory.c | 3 +
mm/memory.c | 4 +
7 files changed, 151 insertions(+), 54 deletions(-)
Index: linux/include/linux/mm.h
===================================================================
--- linux.orig/include/linux/mm.h
+++ linux/include/linux/mm.h
@@ -594,50 +594,11 @@ static inline pte_t maybe_mkwrite(pte_t
* 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
#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
#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 stru
}
#endif
+#ifdef CONFIG_SCHED_NUMA
+#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_SCHED_NUMA */
+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_SCHED_NUMA */
+
static inline struct zone *page_zone(const struct page *page)
{
return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)];
Index: linux/include/linux/mm_types.h
===================================================================
--- linux.orig/include/linux/mm_types.h
+++ linux/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
@@ -398,6 +403,10 @@ struct mm_struct {
#ifdef CONFIG_CPUMASK_OFFSTACK
struct cpumask cpumask_allocation;
#endif
+#ifdef CONFIG_SCHED_NUMA
+ unsigned long numa_next_scan;
+ int numa_scan_seq;
+#endif
struct uprobes_state uprobes_state;
};
Index: linux/include/linux/mmzone.h
===================================================================
--- linux.orig/include/linux/mmzone.h
+++ linux/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
* 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)
Index: linux/include/linux/page-flags-layout.h
===================================================================
--- /dev/null
+++ linux/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_SCHED_NUMA
+#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_SCHED_NUMA) && LAST_CPU_WIDTH == 0
+#define LAST_CPU_NOT_IN_PAGE_FLAGS
+#endif
+
+#endif /* _LINUX_PAGE_FLAGS_LAYOUT */
Index: linux/kernel/bounds.c
===================================================================
--- linux.orig/kernel/bounds.c
+++ linux/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 +18,6 @@ void foo(void)
DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS);
DEFINE(MAX_NR_ZONES, __MAX_NR_ZONES);
DEFINE(NR_PCG_FLAGS, __NR_PCG_FLAGS);
+ DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS));
/* End of constants */
}
Index: linux/mm/huge_memory.c
===================================================================
--- linux.orig/mm/huge_memory.c
+++ linux/mm/huge_memory.c
@@ -746,6 +746,7 @@ void do_huge_pmd_numa_page(struct mm_str
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)))
@@ -760,6 +761,7 @@ void do_huge_pmd_numa_page(struct mm_str
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);
@@ -1441,6 +1443,7 @@ static void __split_huge_page_refcount(s
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));
Index: linux/mm/memory.c
===================================================================
--- linux.orig/mm/memory.c
+++ linux/mm/memory.c
@@ -70,6 +70,10 @@
#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;
--
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