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mm: fold page->_last_nid into page->flags where possible

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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 <mgorman@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Simon Jeons <simon.jeons@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra 2013-02-22 16:34:32 -08:00 committed by Linus Torvalds
parent bbeae5b05e
commit 75980e97da
4 changed files with 62 additions and 10 deletions
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33
include/linux/mm.h
View file

@ -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);

2
include/linux/mm_types.h
View file

@ -174,7 +174,7 @@ struct page {
void *shadow;
#endif
#ifdef CONFIG_NUMA_BALANCING
#ifdef LAST_NID_NOT_IN_PAGE_FLAGS
int _last_nid;
#endif
}

33
include/linux/page-flags-layout.h
View file

@ -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 */

4
mm/memory.c
View file

@ -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;