Commit 7dd80b8a authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Linus Torvalds
Browse files

mm, page_owner: convert page_owner_inited to static key 



CONFIG_PAGE_OWNER attempts to impose negligible runtime overhead when
enabled during compilation, but not actually enabled during runtime by
boot param page_owner=on.  This overhead can be further reduced using
the static key mechanism, which this patch does.

Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 60f30350

Documentation/vm/page_owner.txt

+5 −4
Original line number Diff line number Diff line
@@ -28,10 +28,11 @@ with page owner and page owner is disabled in runtime due to no enabling 
boot option, runtime overhead is marginal. If disabled in runtime, it

doesn't require memory to store owner information, so there is no runtime

memory overhead. And, page owner inserts just two unlikely branches into

the page allocator hotpath and if it returns false then allocation is

done like as the kernel without page owner. These two unlikely branches

would not affect to allocation performance. Following is the kernel's

code size change due to this facility.

the page allocator hotpath and if not enabled, then allocation is done

like as the kernel without page owner. These two unlikely branches should

not affect to allocation performance, especially if the static keys jump

label patching functionality is available. Following is the kernel's code

size change due to this facility.



- Without page owner

   text    data     bss     dec     hex filename

include/linux/page_owner.h

+10 −12
Original line number Diff line number Diff line 
#ifndef __LINUX_PAGE_OWNER_H

#define __LINUX_PAGE_OWNER_H



#include <linux/jump_label.h>



#ifdef CONFIG_PAGE_OWNER

extern bool page_owner_inited;

extern struct static_key_false page_owner_inited;

extern struct page_ext_operations page_owner_ops;



extern void __reset_page_owner(struct page *page, unsigned int order);
@@ -12,27 +14,23 @@ extern gfp_t __get_page_owner_gfp(struct page *page); 


static inline void reset_page_owner(struct page *page, unsigned int order)

{

	if (likely(!page_owner_inited))

		return;



	if (static_branch_unlikely(&page_owner_inited))

		__reset_page_owner(page, order);

}



static inline void set_page_owner(struct page *page,

			unsigned int order, gfp_t gfp_mask)

{

	if (likely(!page_owner_inited))

		return;



	if (static_branch_unlikely(&page_owner_inited))

		__set_page_owner(page, order, gfp_mask);

}



static inline gfp_t get_page_owner_gfp(struct page *page)

{

	if (likely(!page_owner_inited))

		return 0;



	if (static_branch_unlikely(&page_owner_inited))

		return __get_page_owner_gfp(page);

	else

		return 0;

}

#else

static inline void reset_page_owner(struct page *page, unsigned int order)

mm/page_owner.c

+5 −4
Original line number Diff line number Diff line
@@ -5,10 +5,11 @@ 
#include <linux/bootmem.h>

#include <linux/stacktrace.h>

#include <linux/page_owner.h>

#include <linux/jump_label.h>

#include "internal.h"



static bool page_owner_disabled = true;

bool page_owner_inited __read_mostly;

DEFINE_STATIC_KEY_FALSE(page_owner_inited);



static void init_early_allocated_pages(void);
@@ -37,7 +38,7 @@ static void init_page_owner(void) 
	if (page_owner_disabled)

		return;



	page_owner_inited = true;

	static_branch_enable(&page_owner_inited);

	init_early_allocated_pages();

}
@@ -147,7 +148,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) 
	struct page *page;

	struct page_ext *page_ext;



	if (!page_owner_inited)

	if (!static_branch_unlikely(&page_owner_inited))

		return -EINVAL;



	page = NULL;
@@ -295,7 +296,7 @@ static int __init pageowner_init(void) 
{

	struct dentry *dentry;



	if (!page_owner_inited) {

	if (!static_branch_unlikely(&page_owner_inited)) {

		pr_info("page_owner is disabled\n");

		return 0;

	}

mm/vmstat.c

+1 −1
Original line number Diff line number Diff line
@@ -1120,7 +1120,7 @@ static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat) 
#ifdef CONFIG_PAGE_OWNER

	int mtype;



	if (!page_owner_inited)

	if (!static_branch_unlikely(&page_owner_inited))

		return;



	drain_all_pages(NULL);

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