Linux Kernel 5 - Process Management (2)

struct mm_struct { struct vm_area_struct * mmap; /* list of VMAs */ struct rb_root mm_rb; struct vm_area_struct * mmap_cache; /* last find_vma result */ unsigned long free_area_cache; /* first hole */ 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; #ifdef CONFIG_HUGETLB_PAGE int used_hugetlb; #endif /* Architecture-specific MM context */ mm_context_t context; /* coredumping support */ int core_waiters; struct completion *core_startup_done, core_done; /* aio bits */ rwlock_t ioctx_list_lock; struct kioctx *ioctx_list; struct kioctx default_kioctx; };

#define TASK_RUNNING 0 #define TASK_INTERRUPTIBLE 1 #define TASK_UNINTERRUPTIBLE 2 #define TASK_STOPPED 4 #define TASK_ZOMBIE 8 #define TASK_DEAD 16

struct runqueue { spinlock_t lock; unsigned long nr_running, nr_switches, expired_timestamp, nr_uninterruptible; task_t *curr, *idle; struct mm_struct *prev_mm; prio_array_t *active, *expired, arrays[2]; int prev_cpu_load[NR_CPUS]; #ifdef CONFIG_NUMA atomic_t *node_nr_running; int prev_node_load[MAX_NUMNODES]; #endif task_t *migration_thread; struct list_head migration_queue; atomic_t nr_iowait; };

struct prio_array { int nr_active; unsigned long bitmap[BITMAP_SIZE]; struct list_head queue[MAX_PRIO]; }; #define MAX_USER_RT_PRIO 100 #define MAX_RT_PRIO MAX_USER_RT_PRIO #define MAX_PRIO (MAX_RT_PRIO + 40)

array = rq->active; if (unlikely(!array->nr_active)) { /* * Switch the active and expired arrays. */ rq->active = rq->expired; rq->expired = array; array = rq->active; rq->expired_timestamp = 0; }

x++

mov eax, DWORD PTR[x] // read add eax, 1 // operation mov DWORD PTR[x], eax // write

x = 11 //총 접근 횟수 11번 Process A: mov eax, DWORD PTR[x] //x = 11임으로 eax에 11 저장, 12번째 접근 add eax, 1 // eax = 11 + 1임으로, eax = 12 //아직 x에 업데이트된 12를 저장하지 않은 상태 Context Switching // B 프로세스 실행 Process B: mov eax, DWORD PTR[x] // x = 11이 저장되어 있는 상태, 13번째 접근 add eax, 1 // eax = 11 + 1임으로, eax = 12 mov DWORD PTR[x], eax // x의 주소에 12를 저장 Context Switching // A 프로세스 실행 Process A: //레지스터 복원, eax = 12 mov DWORD PTR[x], eax // x의 주소에 12를 저장 x = 12 //총 접근 횟수 13번

struct thread_info { struct task_struct *task; /* main task structure */ struct exec_domain *exec_domain; /* execution domain */ __u32 flags; /* low level flags */ __u32 status; /* thread synchronous flags */ __u32 cpu; /* current CPU */ int preempt_count; /* 0 => preemptable, <0 => BUG */ mm_segment_t addr_limit; struct restart_block restart_block; void __user *sysenter_return; #ifdef CONFIG_X86_32 unsigned long previous_esp; /* ESP of the previous stack in case of nested (IRQ) stacks */ __u8 supervisor_stack[0]; #endif int uaccess_err; };