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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2015-11-06 16:29:50 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-06 17:50:42 -0800
commitf1e61557f0230d51a3df8d825f2c156e75563bff (patch)
treea62bd2c7d3df2b5632b667a46b55cd928dce8002 /mm/page_alloc.c
parent32e7ba1ea1f8d1f0ea4983e768f8b566770a55b3 (diff)
mm: pack compound_dtor and compound_order into one word in struct page
The patch halves space occupied by compound_dtor and compound_order in struct page. For compound_order, it's trivial long -> short conversion. For get_compound_page_dtor(), we now use hardcoded table for destructor lookup and store its index in the struct page instead of direct pointer to destructor. It shouldn't be a big trouble to maintain the table: we have only two destructor and NULL currently. This patch free up one word in tail pages for reuse. This is preparation for the next patch. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b8d560afe266..fae1bd6f9f37 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -229,6 +229,15 @@ static char * const zone_names[MAX_NR_ZONES] = {
#endif
};
+static void free_compound_page(struct page *page);
+compound_page_dtor * const compound_page_dtors[] = {
+ NULL,
+ free_compound_page,
+#ifdef CONFIG_HUGETLB_PAGE
+ free_huge_page,
+#endif
+};
+
int min_free_kbytes = 1024;
int user_min_free_kbytes = -1;
@@ -458,7 +467,7 @@ void prep_compound_page(struct page *page, unsigned long order)
int i;
int nr_pages = 1 << order;
- set_compound_page_dtor(page, free_compound_page);
+ set_compound_page_dtor(page, COMPOUND_PAGE_DTOR);
set_compound_order(page, order);
__SetPageHead(page);
for (i = 1; i < nr_pages; i++) {