summaryrefslogtreecommitdiff
path: root/include
diff options
context:
space:
mode:
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 /include
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 'include')
-rw-r--r--include/linux/mm.h24
-rw-r--r--include/linux/mm_types.h6
2 files changed, 21 insertions, 9 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 906c46a05707..6581c21320cb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -568,18 +568,32 @@ int split_free_page(struct page *page);
/*
* Compound pages have a destructor function. Provide a
* prototype for that function and accessor functions.
- * These are _only_ valid on the head of a PG_compound page.
+ * These are _only_ valid on the head of a compound page.
*/
+typedef void compound_page_dtor(struct page *);
+
+/* Keep the enum in sync with compound_page_dtors array in mm/page_alloc.c */
+enum compound_dtor_id {
+ NULL_COMPOUND_DTOR,
+ COMPOUND_PAGE_DTOR,
+#ifdef CONFIG_HUGETLB_PAGE
+ HUGETLB_PAGE_DTOR,
+#endif
+ NR_COMPOUND_DTORS,
+};
+extern compound_page_dtor * const compound_page_dtors[];
static inline void set_compound_page_dtor(struct page *page,
- compound_page_dtor *dtor)
+ enum compound_dtor_id compound_dtor)
{
- page[1].compound_dtor = dtor;
+ VM_BUG_ON_PAGE(compound_dtor >= NR_COMPOUND_DTORS, page);
+ page[1].compound_dtor = compound_dtor;
}
static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
{
- return page[1].compound_dtor;
+ VM_BUG_ON_PAGE(page[1].compound_dtor >= NR_COMPOUND_DTORS, page);
+ return compound_page_dtors[page[1].compound_dtor];
}
static inline int compound_order(struct page *page)
@@ -589,7 +603,7 @@ static inline int compound_order(struct page *page)
return page[1].compound_order;
}
-static inline void set_compound_order(struct page *page, unsigned long order)
+static inline void set_compound_order(struct page *page, unsigned int order)
{
page[1].compound_order = order;
}
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index c0ec46df6c13..e334ef79cb43 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -28,8 +28,6 @@ struct mem_cgroup;
IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
#define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8)
-typedef void compound_page_dtor(struct page *);
-
/*
* Each physical page in the system has a struct page associated with
* it to keep track of whatever it is we are using the page for at the
@@ -136,8 +134,8 @@ struct page {
*/
/* First tail page of compound page */
struct {
- compound_page_dtor *compound_dtor;
- unsigned long compound_order;
+ unsigned short int compound_dtor;
+ unsigned short int compound_order;
};
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS