android app 加内存,Android系统中添加内存分区（Zone）

1.  添加zone_type枚举类型

//路径: include/linux/Mmzone.h

enum zone_type {

#ifdef CONFIG_ZONE_DMA

/*

* ZONE_DMA is used when there are devices that are not able

* to do DMA to all of addressable memory (ZONE_NORMAL). Then we

* carve out the portion of memory that is needed for these devices.

* The range is arch specific.

*

* Some examples

*

* ArchitectureLimit

* ---------------------------

* parisc, ia64, sparc<4G

* s390<2G

* armVarious

* alphaUnlimited or 0-16MB.

*

* i386, x86_64 and multiple other arches

* <16M.

*/

ZONE_DMA,

#endif

#ifdef CONFIG_ZONE_DMA32

/*

* x86_64 needs two ZONE_DMAs because it supports devices that are

* only able to do DMA to the lower 16M but also 32 bit devices that

* can only do DMA areas below 4G.

*/

ZONE_DMA32,

#endif

/*

* Normal addressable memory is in ZONE_NORMAL. DMA operations can be

* performed on pages in ZONE_NORMAL if the DMA devices support

* transfers to all addressable memory.

*/

ZONE_NORMAL,

ZONE_MEMSWAP,

#ifdef CONFIG_HIGHMEM

/*

* A memory area that is only addressable by the kernel through

* mapping portions into its own address space. This is for example

* used by i386 to allow the kernel to address the memory beyond

* 900MB. The kernel will set up special mappings (page

* table entries on i386) for each page that the kernel needs to

* access.

*/

ZONE_HIGHMEM,

#endif

ZONE_MOVABLE,

__MAX_NR_ZONES

};

其中

ZONE_MEMSWAP,即为添加zone对应的枚举类型

2. 修改内存初始化代码

//路径 arch/arm/mm/Init.c

static void __init arm_bootmem_free(unsigned long min, unsigned long max_low,

unsigned long max_high)添加代码

unsigned long mem_swap_size = 1UL << 15;

unsigned long normal_start = min, normal_end = max_low - mem_swap_size;

zone_size[0] = normal_end - normal_start;

zone_size[ZONE_MEMSWAP] = mem_swap_size;

#ifdef CONFIG_HIGHMEM

zone_size[ZONE_HIGHMEM] = max_high - max_low;

#endif

zhole_size[ZONE_MEMSWAP] = 0UL;

for_each_memblock(memory, reg) {

unsigned long start = memblock_region_memory_base_pfn(reg);

unsigned long end = memblock_region_memory_end_pfn(reg);

if (start < normal_end) {

unsigned long low_end = min(end, normal_end);

zhole_size[0] -= low_end - start;

}

#ifdef CONFIG_HIGHMEM

if (end > max_low) {

unsigned long high_start = max(start, max_low);

zhole_size[ZONE_HIGHMEM] -= end - high_start;

}

#endif

3. 修改内存分配代码

//路径：mm/page_alloc.c

get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,

struct zonelist *zonelist, int high_zoneidx, int alloc_flags,

struct zone *preferred_zone, int migratetype)

在上面函数的下述for循环开头添加如下代码：

for_each_zone_zonelist_nodemask(zone, z, zonelist,

high_zoneidx, nodemask) {

...

if (zone_idx(zone) == ZONE_MEMSWAP)

continue;

...

}

同样是该路径的该函数：

static char * const zone_names[MAX_NR_ZONES] = {

#ifdef CONFIG_ZONE_DMA

"DMA",

#endif

#ifdef CONFIG_ZONE_DMA32

"DMA32",

#endif

"Normal",

"MemSwap",

#ifdef CONFIG_HIGHMEM

"HighMem",

#endif

"Movable",

};