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mm, page_alloc: avoid unnecessary zone lookups during pageblock operations 

Pageblocks have an associated bitmap to store migrate types and whether
the pageblock should be skipped during compaction.  The bitmap may be
associated with a memory section or a zone but the zone is looked up
unconditionally.  The compiler should optimise this away automatically
so this is a cosmetic patch only in many cases.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2016-05-19 17:13:36 -07:00 committed by Linus Torvalds
parent 754078eb45
commit f75fb889d1
1 changed files with 9 additions and 13 deletions
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22
mm/page_alloc.c
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@ -6767,23 +6767,23 @@ void *__init alloc_large_system_hash(const char *tablename,
}
/* Return a pointer to the bitmap storing bits affecting a block of pages */
static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
static inline unsigned long *get_pageblock_bitmap(struct page *page,
unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
return __pfn_to_section(pfn)->pageblock_flags;
#else
return zone->pageblock_flags;
return page_zone(page)->pageblock_flags;
#endif /* CONFIG_SPARSEMEM */
}
static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
pfn &= (PAGES_PER_SECTION-1);
return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#else
pfn = pfn - round_down(zone->zone_start_pfn, pageblock_nr_pages);
pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#endif /* CONFIG_SPARSEMEM */
}
@ -6801,14 +6801,12 @@ unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
unsigned long end_bitidx,
unsigned long mask)
{
struct zone *zone;
unsigned long *bitmap;
unsigned long bitidx, word_bitidx;
unsigned long word;
zone = page_zone(page);
bitmap = get_pageblock_bitmap(zone, pfn);
bitidx = pfn_to_bitidx(zone, pfn);
bitmap = get_pageblock_bitmap(page, pfn);
bitidx = pfn_to_bitidx(page, pfn);
word_bitidx = bitidx / BITS_PER_LONG;
bitidx &= (BITS_PER_LONG-1);
@ -6830,20 +6828,18 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
unsigned long end_bitidx,
unsigned long mask)
{
struct zone *zone;
unsigned long *bitmap;
unsigned long bitidx, word_bitidx;
unsigned long old_word, word;
BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
zone = page_zone(page);
bitmap = get_pageblock_bitmap(zone, pfn);
bitidx = pfn_to_bitidx(zone, pfn);
bitmap = get_pageblock_bitmap(page, pfn);
bitidx = pfn_to_bitidx(page, pfn);
word_bitidx = bitidx / BITS_PER_LONG;
bitidx &= (BITS_PER_LONG-1);
VM_BUG_ON_PAGE(!zone_spans_pfn(zone, pfn), page);
VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
bitidx += end_bitidx;
mask <<= (BITS_PER_LONG - bitidx - 1);