__zone_watermark

函数名称：Return true if free base pages are above 'mark'. For high-order checks it* will return true of the order-0 watermark is reached and there is at least* one free page of a suitable size. Checking now avoids taking the zone lock

函数原型：bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, int classzone_idx, unsigned int alloc_flags, long free_pages)

返回类型：bool

参数：

类型	参数	名称
struct zone *	z
unsigned int	order
unsigned long	mark
int	classzone_idx
unsigned int	alloc_flags
long	free_pages

3394

min等于mark

3396

alloc_harder等于alloc_flags按位与ry to alloc harder 按位或Only MMU archs have async oom victim reclaim - aka oom_reaper so we* cannot assume a reduced access to memory reserves is sufficient for* !MMU的值

3399

free_pages减等于1左移order位的值减1

3401

如果alloc_flags按位与__GFP_HIGH set 则min减等于min除2

3409

如果此条件成立可能性大(为编译器优化)(!alloc_harder)则

3410

free_pages减等于nr_reserved_highatomic

3411

否则

3418

如果alloc_flags按位与Only MMU archs have async oom victim reclaim - aka oom_reaper so we* cannot assume a reduced access to memory reserves is sufficient for* !MMU则min减等于min除2

3420

否则min减等于min除4

3427

如果非alloc_flags按位与allow allocations from CMA areas 的值则free_pages减等于zone_page_state(z, NR_FREE_CMA_PAGES)

3436

如果free_pages小于等于min加关键性内存分配[classzone_idx]则返回:false

3440

如果非order则返回:true

3444

以o小于Free memory management - zoned buddy allocator. 循环

3445

area等于伙伴系统空闲内存页[o]

3448

如果非nr_free则继续下一循环

3451

以mt小于MIGRATE_PCPTYPES 循环

3452

如果非free_area_empty(area, mt)则返回:true

3457

如果alloc_flags按位与allow allocations from CMA areas 且非free_area_empty(area, MIGRATE_CMA)则

3459

返回:true

3462

如果alloc_harder且非链表为空则返回:true

3466

返回:false

**调用者**
名称	描述
zone_watermark_ok
zone_watermark_fast
zone_watermark_ok_safe
should_reclaim_retry	Checks whether it makes sense to retry the reclaim to make a forward progress* for the given allocation request.* We give up when we either have tried MAX_RECLAIM_RETRIES in a row* without success, or when we couldn't even meet the watermark if we

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