The patch titled
mm: page allocator minor speedup
has been added to the -mm tree. Its filename is
mm-page-allocator-minor-speedup.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mm: page allocator minor speedup
From: Nick Piggin <npiggin@xxxxxxx>
Now that we don't put a ZERO_PAGE in the pagetables any more, and the
"remove PageReserved from core mm" patch has had a long time to mature,
let's remove the page reserved logic from the allocator.
This saves several branches and about 100 bytes in some important paths.
Signed-off-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page-flags.h | 6 +++---
mm/page_alloc.c | 31 +++++--------------------------
2 files changed, 8 insertions(+), 29 deletions(-)
diff -puN include/linux/page-flags.h~mm-page-allocator-minor-speedup include/linux/page-flags.h
--- a/include/linux/page-flags.h~mm-page-allocator-minor-speedup
+++ a/include/linux/page-flags.h
@@ -377,7 +377,7 @@ static inline void __ClearPageTail(struc
#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
1 << PG_buddy | 1 << PG_writeback | \
1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
- __PG_UNEVICTABLE | __PG_MLOCKED)
+ __PG_UNEVICTABLE | __PG_MLOCKED | 1 << PG_reserved)
/*
* Flags checked in bad_page(). Pages on the free list should not have
@@ -390,7 +390,7 @@ static inline void __ClearPageTail(struc
* Flags checked when a page is freed. Pages being freed should not have
* these flags set. It they are, there is a problem.
*/
-#define PAGE_FLAGS_CHECK_AT_FREE (PAGE_FLAGS | 1 << PG_reserved)
+#define PAGE_FLAGS_CHECK_AT_FREE (PAGE_FLAGS)
/*
* Flags checked when a page is prepped for return by the page allocator.
@@ -398,7 +398,7 @@ static inline void __ClearPageTail(struc
* is a problem.
*/
#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | \
- 1 << PG_reserved | 1 << PG_dirty | 1 << PG_swapbacked)
+ 1 << PG_dirty | 1 << PG_swapbacked)
#endif /* !__GENERATING_BOUNDS_H */
#endif /* PAGE_FLAGS_H */
diff -puN mm/page_alloc.c~mm-page-allocator-minor-speedup mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page-allocator-minor-speedup
+++ a/mm/page_alloc.c
@@ -449,7 +449,7 @@ static inline void __free_one_page(struc
zone->free_area[order].nr_free++;
}
-static inline int free_pages_check(struct page *page)
+static inline void free_pages_check(struct page *page)
{
free_page_mlock(page);
if (unlikely(page_mapcount(page) |
@@ -462,12 +462,6 @@ static inline int free_pages_check(struc
__ClearPageDirty(page);
if (PageSwapBacked(page))
__ClearPageSwapBacked(page);
- /*
- * For now, we report if PG_reserved was found set, but do not
- * clear it, and do not free the page. But we shall soon need
- * to do more, for when the ZERO_PAGE count wraps negative.
- */
- return PageReserved(page);
}
/*
@@ -512,12 +506,9 @@ static void __free_pages_ok(struct page
{
unsigned long flags;
int i;
- int reserved = 0;
for (i = 0 ; i < (1 << order) ; ++i)
- reserved += free_pages_check(page + i);
- if (reserved)
- return;
+ free_pages_check(page + i);
if (!PageHighMem(page)) {
debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
@@ -596,7 +587,7 @@ static inline void expand(struct zone *z
/*
* This page is about to be returned from the page allocator
*/
-static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
+static void prep_new_page(struct page *page, int order, gfp_t gfp_flags)
{
if (unlikely(page_mapcount(page) |
(page->mapping != NULL) |
@@ -605,13 +596,6 @@ static int prep_new_page(struct page *pa
(page->flags & PAGE_FLAGS_CHECK_AT_PREP)))
bad_page(page);
- /*
- * For now, we report if PG_reserved was found set, but do not
- * clear it, and do not allocate the page: as a safety net.
- */
- if (PageReserved(page))
- return 1;
-
page->flags &= ~(1 << PG_uptodate | 1 << PG_error | 1 << PG_reclaim |
1 << PG_referenced | 1 << PG_arch_1 |
1 << PG_owner_priv_1 | 1 << PG_mappedtodisk
@@ -630,8 +614,6 @@ static int prep_new_page(struct page *pa
if (order && (gfp_flags & __GFP_COMP))
prep_compound_page(page, order);
-
- return 0;
}
/*
@@ -977,8 +959,7 @@ static void free_hot_cold_page(struct pa
if (PageAnon(page))
page->mapping = NULL;
- if (free_pages_check(page))
- return;
+ free_pages_check(page);
if (!PageHighMem(page)) {
debug_check_no_locks_freed(page_address(page), PAGE_SIZE);
@@ -1046,7 +1027,6 @@ static struct page *buffered_rmqueue(str
int cpu;
int migratetype = allocflags_to_migratetype(gfp_flags);
-again:
cpu = get_cpu();
if (likely(order == 0)) {
struct per_cpu_pages *pcp;
@@ -1094,8 +1074,7 @@ again:
put_cpu();
VM_BUG_ON(bad_range(zone, page));
- if (prep_new_page(page, order, gfp_flags))
- goto again;
+ prep_new_page(page, order, gfp_flags);
return page;
failed:
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
origin.patch
linux-next.patch
mm-dirty-page-tracking-race-fix.patch
mm-dirty-page-tracking-race-fix-fix.patch
mm-xip-fix-fault-vs-sparse-page-invalidate-race.patch
mm-xip-ext2-fix-block-allocation-race.patch
vmscan-move-isolate_lru_page-to-vmscanc.patch
mlock-mlocked-pages-are-unevictable.patch
mmap-handle-mlocked-pages-during-map-remap-unmap.patch
vmstat-mlocked-pages-statistics.patch
mm-pagecache-insertion-fewer-atomics.patch
mm-unlockless-reclaim.patch
mm-page-lock-use-lock-bitops.patch
fs-buffer-lock-use-lock-bitops.patch
mm-page-allocator-minor-speedup.patch
reiser4.patch
likeliness-accounting-change-and-cleanup.patch
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