Re: [PATCH 10/19] mm: page_alloc: Reduce number of times page_to_pfn is called
From: Vlastimil Babka
Date: Tue May 13 2014 - 09:27:36 EST
On 05/13/2014 11:45 AM, Mel Gorman wrote:
In the free path we calculate page_to_pfn multiple times. Reduce that.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Just two comments.
I just don't like #define but I can live with that.
__free_one_page() is marked inline so presumably it would reuse
page_to_pfn() result in its caller already. But it seems to me it's
quite large so I wonder if it gets inlined anyway, and if the attribute
still makes sense...
---
include/linux/mmzone.h | 9 +++++++--
include/linux/pageblock-flags.h | 33 +++++++++++++--------------------
mm/page_alloc.c | 34 +++++++++++++++++++---------------
3 files changed, 39 insertions(+), 37 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 835aa3d..bd6f504 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -78,10 +78,15 @@ extern int page_group_by_mobility_disabled;
#define NR_MIGRATETYPE_BITS (PB_migrate_end - PB_migrate + 1)
#define MIGRATETYPE_MASK ((1UL << NR_MIGRATETYPE_BITS) - 1)
-static inline int get_pageblock_migratetype(struct page *page)
+#define get_pageblock_migratetype(page) \
+ get_pfnblock_flags_mask(page, page_to_pfn(page), \
+ PB_migrate_end, MIGRATETYPE_MASK)
+
+static inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
{
BUILD_BUG_ON(PB_migrate_end - PB_migrate != 2);
- return get_pageblock_flags_mask(page, PB_migrate_end, MIGRATETYPE_MASK);
+ return get_pfnblock_flags_mask(page, pfn, PB_migrate_end,
+ MIGRATETYPE_MASK);
}
struct free_area {
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index c08730c..2baeee1 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -65,33 +65,26 @@ extern int pageblock_order;
/* Forward declaration */
struct page;
-unsigned long get_pageblock_flags_mask(struct page *page,
+unsigned long get_pfnblock_flags_mask(struct page *page,
+ unsigned long pfn,
unsigned long end_bitidx,
unsigned long mask);
-void set_pageblock_flags_mask(struct page *page,
+
+void set_pfnblock_flags_mask(struct page *page,
unsigned long flags,
+ unsigned long pfn,
unsigned long end_bitidx,
unsigned long mask);
/* Declarations for getting and setting flags. See mm/page_alloc.c */
-static inline unsigned long get_pageblock_flags_group(struct page *page,
- int start_bitidx, int end_bitidx)
-{
- unsigned long nr_flag_bits = end_bitidx - start_bitidx + 1;
- unsigned long mask = (1 << nr_flag_bits) - 1;
-
- return get_pageblock_flags_mask(page, end_bitidx, mask);
-}
-
-static inline void set_pageblock_flags_group(struct page *page,
- unsigned long flags,
- int start_bitidx, int end_bitidx)
-{
- unsigned long nr_flag_bits = end_bitidx - start_bitidx + 1;
- unsigned long mask = (1 << nr_flag_bits) - 1;
-
- set_pageblock_flags_mask(page, flags, end_bitidx, mask);
-}
+#define get_pageblock_flags_group(page, start_bitidx, end_bitidx) \
+ get_pfnblock_flags_mask(page, page_to_pfn(page), \
+ end_bitidx, \
+ (1 << (end_bitidx - start_bitidx + 1)) - 1)
+#define set_pageblock_flags_group(page, flags, start_bitidx, end_bitidx) \
+ set_pfnblock_flags_mask(page, flags, page_to_pfn(page), \
+ end_bitidx, \
+ (1 << (end_bitidx - start_bitidx + 1)) - 1)
#ifdef CONFIG_COMPACTION
#define get_pageblock_skip(page) \
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b438eb7..3948f0a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -559,6 +559,7 @@ static inline int page_is_buddy(struct page *page, struct page *buddy,
*/
static inline void __free_one_page(struct page *page,
+ unsigned long pfn,
struct zone *zone, unsigned int order,
int migratetype)
{
@@ -575,7 +576,7 @@ static inline void __free_one_page(struct page *page,
VM_BUG_ON(migratetype == -1);
- page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);
+ page_idx = pfn & ((1 << MAX_ORDER) - 1);
VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page);
VM_BUG_ON_PAGE(bad_range(zone, page), page);
@@ -710,7 +711,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
list_del(&page->lru);
mt = get_freepage_migratetype(page);
/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
- __free_one_page(page, zone, 0, mt);
+ __free_one_page(page, page_to_pfn(page), zone, 0, mt);
trace_mm_page_pcpu_drain(page, 0, mt);
if (likely(!is_migrate_isolate_page(page))) {
__mod_zone_page_state(zone, NR_FREE_PAGES, 1);
@@ -722,13 +723,15 @@ static void free_pcppages_bulk(struct zone *zone, int count,
spin_unlock(&zone->lock);
}
-static void free_one_page(struct zone *zone, struct page *page, int order,
+static void free_one_page(struct zone *zone,
+ struct page *page, unsigned long pfn,
+ int order,
int migratetype)
{
spin_lock(&zone->lock);
zone->pages_scanned = 0;
- __free_one_page(page, zone, order, migratetype);
+ __free_one_page(page, pfn, zone, order, migratetype);
if (unlikely(!is_migrate_isolate(migratetype)))
__mod_zone_freepage_state(zone, 1 << order, migratetype);
spin_unlock(&zone->lock);
@@ -765,15 +768,16 @@ static void __free_pages_ok(struct page *page, unsigned int order)
{
unsigned long flags;
int migratetype;
+ unsigned long pfn = page_to_pfn(page);
if (!free_pages_prepare(page, order))
return;
local_irq_save(flags);
__count_vm_events(PGFREE, 1 << order);
- migratetype = get_pageblock_migratetype(page);
+ migratetype = get_pfnblock_migratetype(page, pfn);
set_freepage_migratetype(page, migratetype);
- free_one_page(page_zone(page), page, order, migratetype);
+ free_one_page(page_zone(page), page, pfn, order, migratetype);
local_irq_restore(flags);
}
@@ -1376,12 +1380,13 @@ void free_hot_cold_page(struct page *page, int cold)
struct zone *zone = page_zone(page);
struct per_cpu_pages *pcp;
unsigned long flags;
+ unsigned long pfn = page_to_pfn(page);
int migratetype;
if (!free_pages_prepare(page, 0))
return;
- migratetype = get_pageblock_migratetype(page);
+ migratetype = get_pfnblock_migratetype(page, pfn);
set_freepage_migratetype(page, migratetype);
local_irq_save(flags);
__count_vm_event(PGFREE);
@@ -1395,7 +1400,7 @@ void free_hot_cold_page(struct page *page, int cold)
*/
if (migratetype >= MIGRATE_PCPTYPES) {
if (unlikely(is_migrate_isolate(migratetype))) {
- free_one_page(zone, page, 0, migratetype);
+ free_one_page(zone, page, pfn, 0, migratetype);
goto out;
}
migratetype = MIGRATE_MOVABLE;
@@ -6032,17 +6037,16 @@ static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
* @end_bitidx: The last bit of interest
* returns pageblock_bits flags
*/
-unsigned long get_pageblock_flags_mask(struct page *page,
+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 pfn, bitidx, word_bitidx;
+ unsigned long bitidx, word_bitidx;
unsigned long word;
zone = page_zone(page);
- pfn = page_to_pfn(page);
bitmap = get_pageblock_bitmap(zone, pfn);
bitidx = pfn_to_bitidx(zone, pfn);
word_bitidx = bitidx / BITS_PER_LONG;
@@ -6054,25 +6058,25 @@ unsigned long get_pageblock_flags_mask(struct page *page,
}
/**
- * set_pageblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
+ * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
* @page: The page within the block of interest
* @start_bitidx: The first bit of interest
* @end_bitidx: The last bit of interest
* @flags: The flags to set
*/
-void set_pageblock_flags_mask(struct page *page, unsigned long flags,
+void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
+ unsigned long pfn,
unsigned long end_bitidx,
unsigned long mask)
{
struct zone *zone;
unsigned long *bitmap;
- unsigned long pfn, bitidx, word_bitidx;
+ unsigned long bitidx, word_bitidx;
unsigned long old_word, word;
BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
zone = page_zone(page);
- pfn = page_to_pfn(page);
bitmap = get_pageblock_bitmap(zone, pfn);
bitidx = pfn_to_bitidx(zone, pfn);
word_bitidx = bitidx / BITS_PER_LONG;
--
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