From 75980e97daccfc6babbac7e180ff118537955f5d Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 22 Feb 2013 16:34:32 -0800 Subject: [PATCH] mm: fold page->_last_nid into page->flags where possible page->_last_nid fits into page->flags on 64-bit. The unlikely 32-bit NUMA configuration with NUMA Balancing will still need an extra page field. As Peter notes "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." [mgorman@suse.de: minor modifications] Signed-off-by: Mel Gorman Cc: Peter Zijlstra Cc: Andrea Arcangeli Cc: Ingo Molnar Cc: Simon Jeons Cc: Wanpeng Li Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 33 ++++++++++++++++++++++++++++++- include/linux/mm_types.h | 2 +- include/linux/page-flags-layout.h | 33 +++++++++++++++++++++++-------- mm/memory.c | 4 ++++ 4 files changed, 62 insertions(+), 10 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index c2d7d5993b14..473abbda942e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -581,10 +581,11 @@ 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: | [SECTION] | [NODE] | ZONE | ... | FLAGS | */ +/* Page flags: | [SECTION] | [NODE] | ZONE | [LAST_NID] | ... | 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) /* * Define the bit shifts to access each section. For non-existent @@ -594,6 +595,7 @@ 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_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 @@ -615,6 +617,7 @@ 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_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) @@ -654,6 +657,7 @@ static inline int page_to_nid(const struct page *page) #endif #ifdef CONFIG_NUMA_BALANCING +#ifdef LAST_NID_NOT_IN_PAGE_FLAGS static inline int page_xchg_last_nid(struct page *page, int nid) { return xchg(&page->_last_nid, nid); @@ -668,6 +672,33 @@ static inline void reset_page_last_nid(struct page *page) page->_last_nid = -1; } #else +static inline int page_last_nid(struct page *page) +{ + return (page->flags >> LAST_NID_PGSHIFT) & LAST_NID_MASK; +} + +static inline int page_xchg_last_nid(struct page *page, int nid) +{ + unsigned long old_flags, flags; + int last_nid; + + do { + old_flags = flags = page->flags; + last_nid = page_last_nid(page); + + flags &= ~(LAST_NID_MASK << LAST_NID_PGSHIFT); + flags |= (nid & LAST_NID_MASK) << LAST_NID_PGSHIFT; + } while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags)); + + return last_nid; +} + +static inline void reset_page_last_nid(struct page *page) +{ + page_xchg_last_nid(page, (1 << LAST_NID_SHIFT) - 1); +} +#endif /* LAST_NID_NOT_IN_PAGE_FLAGS */ +#else static inline int page_xchg_last_nid(struct page *page, int nid) { return page_to_nid(page); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index d05d632c716e..ace9a5f01c64 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -174,7 +174,7 @@ struct page { void *shadow; #endif -#ifdef CONFIG_NUMA_BALANCING +#ifdef LAST_NID_NOT_IN_PAGE_FLAGS int _last_nid; #endif } diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h index 316805d6ba1b..93506a114034 100644 --- a/include/linux/page-flags-layout.h +++ b/include/linux/page-flags-layout.h @@ -32,15 +32,16 @@ /* * 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. + * There are five possibilities for how page->flags get laid out. The first + * pair is for the normal case without sparsemem. The second pair is for + * sparsemem when there is plenty of space for node and section information. + * The last is when there is insufficient space in page->flags and a separate + * lookup is necessary. * - * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | - * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | + * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | + * " plus space for last_nid: | NODE | ZONE | LAST_NID ... | FLAGS | + * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | + * " plus space for last_nid: | SECTION | NODE | ZONE | LAST_NID ... | FLAGS | * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS | */ #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) @@ -60,6 +61,18 @@ #define NODES_WIDTH 0 #endif +#ifdef CONFIG_NUMA_BALANCING +#define LAST_NID_SHIFT NODES_SHIFT +#else +#define LAST_NID_SHIFT 0 +#endif + +#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_NID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS +#define LAST_NID_WIDTH LAST_NID_SHIFT +#else +#define LAST_NID_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. @@ -68,4 +81,8 @@ #define NODE_NOT_IN_PAGE_FLAGS #endif +#if defined(CONFIG_NUMA_BALANCING) && LAST_NID_WIDTH == 0 +#define LAST_NID_NOT_IN_PAGE_FLAGS +#endif + #endif /* _LINUX_PAGE_FLAGS_LAYOUT */ diff --git a/mm/memory.c b/mm/memory.c index 7837ceacf090..054250ee4a68 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -69,6 +69,10 @@ #include "internal.h" +#ifdef LAST_NID_NOT_IN_PAGE_FLAGS +#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_nid. +#endif + #ifndef CONFIG_NEED_MULTIPLE_NODES /* use the per-pgdat data instead for discontigmem - mbligh */ unsigned long max_mapnr; -- 2.20.1