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buddy: init and alloc

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gatieme
2021-03-06 22:28:28 +08:00
parent 442cd88f8b
commit b5df9f2dd0
2 changed files with 23 additions and 19 deletions
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study/kernel/02-memory/04-buddy/02-initialization/README.md
+3
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@@ -76,14 +76,17 @@ start_kernel()
```cpp
|---->page_alloc_init()
|
|---->hotcpu_notifier(page_alloc_cpu_notifier, 0);
| 不考虑热插拔CPU
|
|---->pidhash_init()
|
| 详见下文.
| 根据低端内存页数和散列度，分配hash空间，并赋予pid_hash
|
|---->vfs_caches_init_early()
|
|---->dcache_init_early()
| dentry_hashtable空间，d_hash_shift, h_hash_mask赋值；
| 同pidhash_init();
study/kernel/02-memory/04-buddy/04-alloc_page/README.md
+20 -19
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@@ -1,4 +1,4 @@
服务器体系与共享存储器架构
伙伴系统之页面分配
=======
| 日期 | 内核版本 | 架构| 作者 | GitHub| CSDN |
@@ -64,9 +64,7 @@ Linux内核使用二进制伙伴算法来管理和分配物理内存页面, 该
## 2.1 alloc_page 的流程
-------
##2.2 伙伴系统的心脏 __alloc_pages_nodemask
## 2.2 伙伴系统的心脏 `__alloc_pages_nodemask`
-------
内核源代码将`__alloc_pages_nodemask` 称之为"伙伴系统的心脏"(`the 'heart' of the zoned buddy allocator`), 因为它处理的是实质性的内存分配.
@@ -75,7 +73,7 @@ Linux内核使用二进制伙伴算法来管理和分配物理内存页面, 该
`__alloc_pages_nodemask`函数定义在[include/linux/gfp.h?v=4.7#L428](http://lxr.free-electrons.com/source/include/linux/gfp.h?v=4.7#L428)
`__alloc_pages_nodemask` 函数定义在 [include/linux/gfp.h?v=4.7#L428](http://lxr.free-electrons.com/source/include/linux/gfp.h?v=4.7#L428)
通过使用标志、内存域修饰符和各个分配函数, 内核提供了一种非常灵活的内存分配体系.尽管如此, 所有接口函数都可以追溯到一个简单的基本函数(alloc_pages_node)
@@ -181,8 +179,7 @@ EXPORT_SYMBOL(__get_free_pages);
# 3 alloc_pages函数分配页
# 3 alloc_pages 函数分配页
-------
## 3.1 alloc_pages 接口实现
@@ -217,11 +214,16 @@ alloc_pages(gfp_t gfp_mask, unsigned int order)
-------
```cpp
alloc_pages
alloc_pages_node
__alloc_pages_node
__alloc_pages
__alloc_pages_nodemask
|---->alloc_pages
|
|---->alloc_pages_node
|
|---->__alloc_pages_node
|
|---->__alloc_pages
|
|---->__alloc_pages_nodemask
|
```
@@ -253,7 +255,7 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask,
`__alloc_pages_node`函数定义在[include/linux/gfp.h?v=4.7, line 435)](http://lxr.free-electrons.com/source/include/linux/gfp.h?v=4.7#L435), 如下所示
```cpp
// http://lxr.free-electrons.com/source/include/linux/gfp.h?v=4.7#L435
// https://elixir.bootlin.com/linux/v5.10/source/include/linux/gfp.h#L519
/*
* Allocate pages, preferring the node given as nid. The node must be valid and
* online. For more general interface, see alloc_pages_node().
@@ -262,9 +264,9 @@ static inline struct page *
__alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
{
VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
VM_WARN_ON(!node_online(nid));
VM_WARN_ON((gfp_mask & __GFP_THISNODE) && !node_online(nid));
return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
return __alloc_pages(gfp_mask, order, nid);
}
```
@@ -274,12 +276,11 @@ __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
现在`__alloc_pages`函数没什么特别的, 它直接将自己的所有信息传递给`__alloc_pages_nodemask`来完成内存的分配
```cpp
// http://lxr.free-electrons.com/source/include/linux/gfp.h?v=4.7#L428
// https://elixir.bootlin.com/linux/v5.10/source/include/linux/gfp.h#L509
static inline struct page *
__alloc_pages(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist)
__alloc_pages(gfp_t gfp_mask, unsigned int order, int preferred_nid)
{
return __alloc_pages_nodemask(gfp_mask, order, zonelist, NULL);
return __alloc_pages_nodemask(gfp_mask, order, preferred_nid, NULL);
}
```