Buddy System. More...

Macros
#define	__DEBUG_HEADER__ "[BUDDY ]"
	Change header.

#define	__DEBUG_LEVEL__ LOGLEVEL_NOTICE
	Set log level.

#define	LOW_WATERMARK_LEVEL 10
	Cache level low limit after which allocation starts.

#define	HIGH_WATERMARK_LEVEL 70
	Cache level high limit, above it deallocation happens.

#define	MID_WATERMARK_LEVEL ((LOW_WATERMARK_LEVEL + HIGH_WATERMARK_LEVEL) / 2)
	Cache level midway limit.

Enumerations
enum	bb_flag { FREE_PAGE = 0 , ROOT_PAGE = 1 }
	Bitwise flags for identifying page types and statuses. More...

Functions
static void	__bb_set_flag (bb_page_t *page, int flag)
	Sets the given flag in the page. More...

static void	__bb_clear_flag (bb_page_t *page, int flag)
	Clears the given flag from the page. More...

static int	__bb_test_flag (bb_page_t *page, int flag)
	Gets the given flag from the page. More...

static bb_page_t *	__get_page_from_base (bb_instance_t instance, bb_page_t base, unsigned int index)
	Returns the page at the given index, starting from the given base. More...

static bb_page_t *	__get_page_at_index (bb_instance_t *instance, unsigned int index)
	Returns the page at the given index, starting from the first page of the BB system. More...

static unsigned int	__get_page_range (bb_instance_t instance, bb_page_t begin, bb_page_t *end)
	Computes the number of pages separating the two pages (begin, end). More...

static unsigned long	__get_buddy_at_index (unsigned long page_idx, unsigned int order)
	Get the buddy index of a page. More...

static bb_free_area_t *	__get_area_of_order (bb_instance_t *instance, unsigned int order)
	Returns the pointer to the free-area manager for the given order. More...

static int	__page_is_buddy (bb_page_t *page, unsigned int order)
	Checks if the page is FREE and has the same order. More...

bb_page_t *	bb_alloc_pages (bb_instance_t *instance, unsigned int order)
	Allocate a block of page frames of size 2^order. More...

void	bb_free_pages (bb_instance_t instance, bb_page_t page)
	Free a block of page frames of size 2^order. More...

void	buddy_system_init (bb_instance_t instance, const char name, void *pages_start, uint32_t bbpage_offset, uint32_t pages_stride, uint32_t pages_count)
	Initialize Buddy System. More...

void	buddy_system_dump (bb_instance_t *instance)
	Print the size of free_list of each free_area. More...

unsigned long	buddy_system_get_total_space (bb_instance_t *instance)
	Returns the total space for the given instance. More...

unsigned long	buddy_system_get_free_space (bb_instance_t *instance)
	Returns the free space for the given instance. More...

unsigned long	buddy_system_get_cached_space (bb_instance_t *instance)
	Returns the cached space for the given instance. More...

static void	__cache_extend (bb_instance_t *instance, int count)
	Extenmds the cache of the given amount. More...

static void	__cache_shrink (bb_instance_t *instance, int count)
	Shrinks the cache. More...

static bb_page_t *	__cached_alloc (bb_instance_t *instance)
	Allocate memory using the given cache. More...

static void	__cached_free (bb_instance_t instance, bb_page_t page)
	Frees the memory of the allocated page. More...

bb_page_t *	bb_alloc_page_cached (bb_instance_t *instance)
	Alloc a page using bb cache. More...

void	bb_free_page_cached (bb_instance_t instance, bb_page_t page)
	Free a page allocated with bb_alloc_page_cached. More...

Detailed Description

Buddy System.

Copyright: (c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Enumeration Type Documentation

◆ bb_flag

enum bb_flag

Bitwise flags for identifying page types and statuses.

Enumerator
FREE_PAGE	Bit position that identifies when a page is free or not.
ROOT_PAGE	Bit position that identifies when a page is the root page.

Function Documentation

◆ __bb_clear_flag()

static void __bb_clear_flag	(	bb_page_t *	page,
		int	flag
	)

inlinestatic

Clears the given flag from the page.

Parameters

page	The page of which we want to modify the flag.
flag	The flag we want to clear.

◆ __bb_set_flag()

static void __bb_set_flag	(	bb_page_t *	page,
		int	flag
	)

inlinestatic

Sets the given flag in the page.

Parameters

page	The page of which we want to modify the flag.
flag	The flag we want to set.

◆ __bb_test_flag()

static int __bb_test_flag	(	bb_page_t *	page,
		int	flag
	)

inlinestatic

Gets the given flag from the page.

Parameters

page	The page of which we want to modify the flag.
flag	The flag we want to test.

Returns: 1 if the bit is set, 0 otherwise.

◆ __cache_extend()

static void __cache_extend	(	bb_instance_t *	instance,
		int	count
	)

static

Extenmds the cache of the given amount.

Parameters

instance	the cache instance.
count	the amount to extend to.

◆ __cache_shrink()

static void __cache_shrink	(	bb_instance_t *	instance,
		int	count
	)

static

Shrinks the cache.

Parameters

instance	the cache instance.
count	the amount to shrink.

◆ __cached_alloc()

static bb_page_t* __cached_alloc ( bb_instance_t * instance )

static

Allocate memory using the given cache.

Parameters

instance the cache instance.

Returns: a pointer to the allocated page.

◆ __cached_free()

static void __cached_free	(	bb_instance_t *	instance,
		bb_page_t *	page
	)

static

Frees the memory of the allocated page.

Parameters

instance	the cache instance.
page	a pointer to the allocated page.

◆ __get_area_of_order()

static bb_free_area_t* __get_area_of_order	(	bb_instance_t *	instance,
		unsigned int	order
	)

inlinestatic

Returns the pointer to the free-area manager for the given order.

Parameters

instance	the buddysystem instance.
order	the desired order.

Returns: pointer to the free-area manager.

◆ __get_buddy_at_index()

static unsigned long __get_buddy_at_index	(	unsigned long	page_idx,
		unsigned int	order
	)

inlinestatic

Get the buddy index of a page.

--------------------— xor --------------------— | page_idx ^ (1UL << order) = buddy_idx | | 1 1 0 |

| 0 1 1 |

If the bit of page_idx that corresponds to the block size, is 1, then we have to take the block on the left (0), otherwise we have to take the block on the right (1).

Parameters

page_idx	the page index.
order	the logarithm of the size of the block.

Returns: the page index of the buddy of page.

◆ __get_page_at_index()

static bb_page_t* __get_page_at_index	(	bb_instance_t *	instance,
		unsigned int	index
	)

inlinestatic

Returns the page at the given index, starting from the first page of the BB system.

Parameters

instance	The buddy system instance we are working with.
index	The number of pages we want to move from the first page.

Returns: The page we found.

◆ __get_page_from_base()

static bb_page_t* __get_page_from_base	(	bb_instance_t *	instance,
		bb_page_t *	base,
		unsigned int	index
	)

inlinestatic

Returns the page at the given index, starting from the given base.

Parameters

instance	The buddy system instance we are working with.
base	The base page from which we move at the given index.
index	The number of pages we want to move from the base.

Returns: The page we found.

◆ __get_page_range()

static unsigned int __get_page_range	(	bb_instance_t *	instance,
		bb_page_t *	begin,
		bb_page_t *	end
	)

inlinestatic

Computes the number of pages separating the two pages (begin, end).

Parameters

instance	the buddy system instance we are working with.
begin	the first page.
end	the second page.

Returns: The number of pages between begin and end.

◆ __page_is_buddy()

static int __page_is_buddy	(	bb_page_t *	page,
		unsigned int	order
	)

inlinestatic

Checks if the page is FREE and has the same order.

Parameters

page	the page to check.
order	the oder to check.

Returns: 1 if the page is buddy, 0 otherwise.

◆ bb_alloc_page_cached()

bb_page_t* bb_alloc_page_cached ( bb_instance_t * instance )

Alloc a page using bb cache.

Parameters

instance Buddy system instance.

Returns: An allocated page.

◆ bb_alloc_pages()

bb_page_t* bb_alloc_pages	(	bb_instance_t *	instance,
		unsigned int	order
	)

Allocate a block of page frames of size 2^order.

Parameters

instance	A buddy system instance.
order	The logarithm of the size of the block.

Returns: The address of the first page descriptor of the block, or NULL.

◆ bb_free_page_cached()

void bb_free_page_cached	(	bb_instance_t *	instance,
		bb_page_t *	page
	)

Free a page allocated with bb_alloc_page_cached.

Parameters

instance	Buddy system instance.
page	The address of the first page descriptor of the block.

◆ bb_free_pages()

void bb_free_pages	(	bb_instance_t *	instance,
		bb_page_t *	page
	)

Free a block of page frames of size 2^order.

Parameters

instance	A buddy system instance.
page	The address of the first page descriptor of the block.

◆ buddy_system_dump()

void buddy_system_dump ( bb_instance_t * instance )

Print the size of free_list of each free_area.

Parameters

instance A buddy system instance.

◆ buddy_system_get_cached_space()

unsigned long buddy_system_get_cached_space ( bb_instance_t * instance )

Returns the cached space for the given instance.

Parameters

instance A buddy system instance.

Returns: The requested total sapce.

◆ buddy_system_get_free_space()

unsigned long buddy_system_get_free_space ( bb_instance_t * instance )

Returns the free space for the given instance.

Parameters

instance A buddy system instance.

Returns: The requested total sapce.

◆ buddy_system_get_total_space()

unsigned long buddy_system_get_total_space ( bb_instance_t * instance )

Returns the total space for the given instance.

Parameters

instance A buddy system instance.

Returns: The requested total sapce.

◆ buddy_system_init()

void buddy_system_init	(	bb_instance_t *	instance,
		const char *	name,
		void *	pages_start,
		uint32_t	bbpage_offset,
		uint32_t	pages_stride,
		uint32_t	pages_count
	)

Initialize Buddy System.

Parameters

instance	A buddysystem instance.
name	The name of the current instance (for debug purposes)
pages_start	The start address of the page structures
bbpage_offset	The offset from the start of the whole page of the bb_page_t struct.
pages_stride	The (padded) size of the whole page structure
pages_count	The number of pages in this region

Macros

Enumerations

Functions

Detailed Description

Enumeration Type Documentation

◆ bb_flag

Function Documentation

◆ __bb_clear_flag()

◆ __bb_set_flag()

◆ __bb_test_flag()

◆ __cache_extend()

◆ __cache_shrink()

◆ __cached_alloc()

◆ __cached_free()

◆ __get_area_of_order()

◆ __get_buddy_at_index()

| 0 1 1 |

◆ __get_page_at_index()

◆ __get_page_from_base()

◆ __get_page_range()

◆ __page_is_buddy()

◆ bb_alloc_page_cached()

◆ bb_alloc_pages()

◆ bb_free_page_cached()

◆ bb_free_pages()

◆ buddy_system_dump()

◆ buddy_system_get_cached_space()

◆ buddy_system_get_free_space()

◆ buddy_system_get_total_space()

◆ buddy_system_init()