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Subject[PATCH v9 06/12] mm: zero struct pages during initialization
Date
Add struct page zeroing as a part of initialization of other fields in
__init_single_page().

This single thread performance collected on: Intel(R) Xeon(R) CPU E7-8895
v3 @ 2.60GHz with 1T of memory (268400646 pages in 8 nodes):

BASE FIX
sparse_init 11.244671836s 0.007199623s
zone_sizes_init 4.879775891s 8.355182299s
--------------------------
Total 16.124447727s 8.362381922s

sparse_init is where memory for struct pages is zeroed, and the zeroing
part is moved later in this patch into __init_single_page(), which is
called from zone_sizes_init().

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Bob Picco <bob.picco@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
include/linux/mm.h | 9 +++++++++
mm/page_alloc.c | 1 +
2 files changed, 10 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f8c10d336e42..50b74d628243 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -94,6 +94,15 @@ extern int mmap_rnd_compat_bits __read_mostly;
#define mm_forbids_zeropage(X) (0)
#endif

+/*
+ * On some architectures it is expensive to call memset() for small sizes.
+ * Those architectures should provide their own implementation of "struct page"
+ * zeroing by defining this macro in <asm/pgtable.h>.
+ */
+#ifndef mm_zero_struct_page
+#define mm_zero_struct_page(pp) ((void)memset((pp), 0, sizeof(struct page)))
+#endif
+
/*
* Default maximum number of active map areas, this limits the number of vmas
* per mm struct. Users can overwrite this number by sysctl but there is a
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a8dbd405ed94..4b630ee91430 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1170,6 +1170,7 @@ static void free_one_page(struct zone *zone,
static void __meminit __init_single_page(struct page *page, unsigned long pfn,
unsigned long zone, int nid)
{
+ mm_zero_struct_page(page);
set_page_links(page, zone, nid, pfn);
init_page_count(page);
page_mapcount_reset(page);
--
2.14.1
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