* [PATCH 2/4] mm/page_alloc.c: extract the common part in pfn_to_bitidx()
2020-06-23 12:41 [PATCH 1/4] mm/page_alloc.c: replace the definition of NR_MIGRATETYPE_BITS with PB_migratetype_bits Wei Yang
@ 2020-06-23 12:41 ` Wei Yang
2020-06-23 12:42 ` [PATCH 3/4] mm/page_alloc.c: simplify pageblock bitmap access Wei Yang
2020-06-23 12:42 ` [PATCH 4/4] mm/page_alloc.c: remove unnecessary end_bitidx for [set|get]_pfnblock_flags_mask() Wei Yang
2 siblings, 0 replies; 4+ messages in thread
From: Wei Yang @ 2020-06-23 12:41 UTC (permalink / raw)
To: mgorman, akpm, richard.weiyang; +Cc: linux-mm, linux-kernel
The return value calculation is the same both for SPARSEMEM or not.
Just took it out.
Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
---
mm/page_alloc.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 727751219003..efc2c355ac52 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -459,11 +459,10 @@ static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
{
#ifdef CONFIG_SPARSEMEM
pfn &= (PAGES_PER_SECTION-1);
- return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#else
pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
- return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
#endif /* CONFIG_SPARSEMEM */
+ return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
}
/**
--
2.20.1 (Apple Git-117)
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH 3/4] mm/page_alloc.c: simplify pageblock bitmap access
2020-06-23 12:41 [PATCH 1/4] mm/page_alloc.c: replace the definition of NR_MIGRATETYPE_BITS with PB_migratetype_bits Wei Yang
2020-06-23 12:41 ` [PATCH 2/4] mm/page_alloc.c: extract the common part in pfn_to_bitidx() Wei Yang
@ 2020-06-23 12:42 ` Wei Yang
2020-06-23 12:42 ` [PATCH 4/4] mm/page_alloc.c: remove unnecessary end_bitidx for [set|get]_pfnblock_flags_mask() Wei Yang
2 siblings, 0 replies; 4+ messages in thread
From: Wei Yang @ 2020-06-23 12:42 UTC (permalink / raw)
To: mgorman, akpm, richard.weiyang; +Cc: linux-mm, linux-kernel
From commit e58469bafd05 ("mm: page_alloc: use word-based accesses for
get/set pageblock bitmaps"), pageblock bitmap is accessed with
word-based access. This operation could be simplified a little.
Intuitively, if we want to get a bit range [start_idx, end_idx] in a
word, we can do like this:
mask = (1 << (end_bitidx - start_bitidx + 1)) - 1;
ret = (word >> start_idx) & mask;
And also if we want to set a bit range [start_idx, end_idx] with flags, we
can do the same by just shift start_bitidx.
By doing so we reduce some instructions for these two helper functions:
Before Patched
set_pfnblock_flags_mask 209 198(-5%)
get_pfnblock_flags_mask 101 87(-13%)
Since the syntax is changed a little, we need to check the whole 4-bit
migrate_type instead of part of it.
CC: Mel Gorman <mgorman@suse.de>
Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
---
include/linux/pageblock-flags.h | 22 +++++++---------------
mm/page_alloc.c | 13 ++++++-------
2 files changed, 13 insertions(+), 22 deletions(-)
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index c066fec5b74b..6556e4474409 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -66,25 +66,17 @@ void set_pfnblock_flags_mask(struct page *page,
unsigned long mask);
/* Declarations for getting and setting flags. See mm/page_alloc.c */
-#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) \
- get_pageblock_flags_group(page, PB_migrate_skip, \
- PB_migrate_skip)
+ get_pfnblock_flags_mask(page, page_to_pfn(page), \
+ PB_migrate_skip, (1 << (PB_migrate_skip)))
#define clear_pageblock_skip(page) \
- set_pageblock_flags_group(page, 0, PB_migrate_skip, \
- PB_migrate_skip)
+ set_pfnblock_flags_mask(page, 0, page_to_pfn(page), \
+ PB_migrate_skip, (1 << PB_migrate_skip))
#define set_pageblock_skip(page) \
- set_pageblock_flags_group(page, 1, PB_migrate_skip, \
- PB_migrate_skip)
+ set_pfnblock_flags_mask(page, (1 << PB_migrate_skip), \
+ page_to_pfn(page), \
+ PB_migrate_skip, (1 << PB_migrate_skip))
#else
static inline bool get_pageblock_skip(struct page *page)
{
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index efc2c355ac52..9da416eec284 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -489,8 +489,7 @@ static __always_inline unsigned long __get_pfnblock_flags_mask(struct page *page
bitidx &= (BITS_PER_LONG-1);
word = bitmap[word_bitidx];
- bitidx += end_bitidx;
- return (word >> (BITS_PER_LONG - bitidx - 1)) & mask;
+ return (word >> bitidx) & mask;
}
unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
@@ -532,9 +531,8 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
- bitidx += end_bitidx;
- mask <<= (BITS_PER_LONG - bitidx - 1);
- flags <<= (BITS_PER_LONG - bitidx - 1);
+ mask <<= bitidx;
+ flags <<= bitidx;
word = READ_ONCE(bitmap[word_bitidx]);
for (;;) {
@@ -551,8 +549,9 @@ void set_pageblock_migratetype(struct page *page, int migratetype)
migratetype < MIGRATE_PCPTYPES))
migratetype = MIGRATE_UNMOVABLE;
- set_pageblock_flags_group(page, (unsigned long)migratetype,
- PB_migrate, PB_migrate_end);
+ set_pfnblock_flags_mask(page, (unsigned long)migratetype,
+ page_to_pfn(page), PB_migrate_end,
+ MIGRATETYPE_MASK);
}
#ifdef CONFIG_DEBUG_VM
--
2.20.1 (Apple Git-117)
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH 4/4] mm/page_alloc.c: remove unnecessary end_bitidx for [set|get]_pfnblock_flags_mask()
2020-06-23 12:41 [PATCH 1/4] mm/page_alloc.c: replace the definition of NR_MIGRATETYPE_BITS with PB_migratetype_bits Wei Yang
2020-06-23 12:41 ` [PATCH 2/4] mm/page_alloc.c: extract the common part in pfn_to_bitidx() Wei Yang
2020-06-23 12:42 ` [PATCH 3/4] mm/page_alloc.c: simplify pageblock bitmap access Wei Yang
@ 2020-06-23 12:42 ` Wei Yang
2 siblings, 0 replies; 4+ messages in thread
From: Wei Yang @ 2020-06-23 12:42 UTC (permalink / raw)
To: mgorman, akpm, richard.weiyang; +Cc: linux-mm, linux-kernel
After previous cleanup, the end_bitidx is not necessary any more.
Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
---
include/linux/mmzone.h | 3 +--
include/linux/pageblock-flags.h | 8 +++-----
mm/page_alloc.c | 15 +++++----------
3 files changed, 9 insertions(+), 17 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index eeb0da54ff5f..e55dd385c422 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -91,8 +91,7 @@ extern int page_group_by_mobility_disabled;
#define MIGRATETYPE_MASK ((1UL << PB_migratetype_bits) - 1)
#define get_pageblock_migratetype(page) \
- get_pfnblock_flags_mask(page, page_to_pfn(page), \
- PB_migrate_end, MIGRATETYPE_MASK)
+ get_pfnblock_flags_mask(page, page_to_pfn(page), MIGRATETYPE_MASK)
struct free_area {
struct list_head free_list[MIGRATE_TYPES];
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index 6556e4474409..fff52ad370c1 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -56,27 +56,25 @@ struct page;
unsigned long get_pfnblock_flags_mask(struct page *page,
unsigned long pfn,
- unsigned long end_bitidx,
unsigned long mask);
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 */
#ifdef CONFIG_COMPACTION
#define get_pageblock_skip(page) \
get_pfnblock_flags_mask(page, page_to_pfn(page), \
- PB_migrate_skip, (1 << (PB_migrate_skip)))
+ (1 << (PB_migrate_skip)))
#define clear_pageblock_skip(page) \
set_pfnblock_flags_mask(page, 0, page_to_pfn(page), \
- PB_migrate_skip, (1 << PB_migrate_skip))
+ (1 << PB_migrate_skip))
#define set_pageblock_skip(page) \
set_pfnblock_flags_mask(page, (1 << PB_migrate_skip), \
page_to_pfn(page), \
- PB_migrate_skip, (1 << PB_migrate_skip))
+ (1 << PB_migrate_skip))
#else
static inline bool get_pageblock_skip(struct page *page)
{
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9da416eec284..dabec744ceff 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -469,14 +469,13 @@ static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
* get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
* @page: The page within the block of interest
* @pfn: The target page frame number
- * @end_bitidx: The last bit of interest to retrieve
* @mask: mask of bits that the caller is interested in
*
* Return: pageblock_bits flags
*/
-static __always_inline unsigned long __get_pfnblock_flags_mask(struct page *page,
+static __always_inline
+unsigned long __get_pfnblock_flags_mask(struct page *page,
unsigned long pfn,
- unsigned long end_bitidx,
unsigned long mask)
{
unsigned long *bitmap;
@@ -493,15 +492,14 @@ static __always_inline unsigned long __get_pfnblock_flags_mask(struct page *page
}
unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
- unsigned long end_bitidx,
unsigned long mask)
{
- return __get_pfnblock_flags_mask(page, pfn, end_bitidx, mask);
+ return __get_pfnblock_flags_mask(page, pfn, mask);
}
static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
{
- return __get_pfnblock_flags_mask(page, pfn, PB_migrate_end, MIGRATETYPE_MASK);
+ return __get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
}
/**
@@ -509,12 +507,10 @@ static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned
* @page: The page within the block of interest
* @flags: The flags to set
* @pfn: The target page frame number
- * @end_bitidx: The last bit of interest
* @mask: mask of bits that the caller is interested in
*/
void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
unsigned long pfn,
- unsigned long end_bitidx,
unsigned long mask)
{
unsigned long *bitmap;
@@ -550,8 +546,7 @@ void set_pageblock_migratetype(struct page *page, int migratetype)
migratetype = MIGRATE_UNMOVABLE;
set_pfnblock_flags_mask(page, (unsigned long)migratetype,
- page_to_pfn(page), PB_migrate_end,
- MIGRATETYPE_MASK);
+ page_to_pfn(page), MIGRATETYPE_MASK);
}
#ifdef CONFIG_DEBUG_VM
--
2.20.1 (Apple Git-117)
^ permalink raw reply [flat|nested] 4+ messages in thread