Linuxカーネルの仮想メモリ管理(一)
Linuxカーネルの仮想メモリの管理は、プロセスをベースにしており、各プロセスには自分の空き容量があります.システム空間はすべてのプロセスで共有されています.仮想空間に対してよく使うデータ構造vm_アーアアウstructで説明します
区間の数が大きい時にAVLツリーを作ります.検索時間の複雑さはolog(n)です.そのうちvm_mm指向mm_struct構造は、プロセスユーザ空間の抽象であり、task_structの中に該当する針がmm_を指しています.struct
struct vm_area_struct {
struct mm_struct * vm_mm; /* The address space we belong to. */
unsigned long vm_start; /* Our start address within vm_mm. */
unsigned long vm_end; /* The first byte after our end address
within vm_mm. */
/* linked list of VM areas per task, sorted by address */
struct vm_area_struct *vm_next;
pgprot_t vm_page_prot; /* Access permissions of this VMA. */
unsigned long vm_flags; /* Flags, listed below. */
rb_node_t vm_rb;
/*
* For areas with an address space and backing store,
* one of the address_space->i_mmap{,shared} lists,
* for shm areas, the list of attaches, otherwise unused.
*/
struct vm_area_struct *vm_next_share;
struct vm_area_struct **vm_pprev_share;
/* Function pointers to deal with this struct. */
struct vm_operations_struct * vm_ops;
/* Information about our backing store: */
unsigned long vm_pgoff; /* Offset (within vm_file) in PAGE_SIZE
units, *not* PAGE_CACHE_SIZE */
struct file * vm_file; /* File we map to (can be NULL). */
unsigned long vm_raend; /* XXX: put full readahead info here. */
void * vm_private_data; /* was vm_pte (shared mem) */
};区間の数が大きい時にAVLツリーを作ります.検索時間の複雑さはolog(n)です.そのうちvm_mm指向mm_struct構造は、プロセスユーザ空間の抽象であり、task_structの中に該当する針がmm_を指しています.struct
struct mm_struct {
struct vm_area_struct * mmap; /* list of VMAs */
rb_root_t mm_rb;
struct vm_area_struct * mmap_cache; /* last find_vma result */
pgd_t * pgd;
atomic_t mm_users; /* How many users with user space? */
atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */
int map_count; /* number of VMAs */
struct rw_semaphore mmap_sem;
spinlock_t page_table_lock; /* Protects task page tables and mm->rss */
struct list_head mmlist; /* List of all active mm's. These are globally strung
* together off init_mm.mmlist, and are protected
* by mmlist_lock
*/
unsigned long start_code, end_code, start_data, end_data;
unsigned long start_brk, brk, start_stack;
unsigned long arg_start, arg_end, env_start, env_end;
unsigned long rss, total_vm, locked_vm;
unsigned long def_flags;
unsigned long cpu_vm_mask;
unsigned long swap_address;
unsigned dumpable:1;
/* Architecture-specific MM context */
mm_context_t context;
};