Linux下进程描述（1）—进程控制块【转】

1  pid_t pid;   //这个是进程号
2  pid_t tgid;  //这个是进程组号 3 pid_t Uid; //用户标识符 4 pid_t Euid; //有效用户标识符 5 pid_t egid; //有效组标识符 6 pid_t Suid; //备份用户标识符 7 pid_t sgid; //备份组标识符 8 pid_t Fsuid; //文件系统用户标识符 9 pid_t fsgid; //文件系统组标识符

1 /* linux-2.6.38.8/include/linux/threads.h */  
2 #define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 :0x8000)

 1   volatile long state;  
 2    int exit_state;  4 /*state成员的可能取值如下：*/  5 #define TASK_RUNNING 0 //TASK_RUNNING表示进程要么正在执行，要么正要准备执行。  6 #define TASK_INTERRUPTIBLE 1 //TASK_INTERRUPTIBLE表示进程被阻塞（睡眠），直到某个条件变为真。条件一旦达成，进程的状态就被设置为TASK_RUNNING。  7 #define TASK_UNINTERRUPTIBLE 2 //TASK_UNINTERRUPTIBLE的意义与TASK_INTERRUPTIBLE类似，除了不能通过接受一个信号来唤醒以外。  8 #define __TASK_STOPPED 4 // __TASK_STOPPED表示进程被停止执行。  9 #define __TASK_TRACED 8 //__TASK_TRACED表示进程被debugger等进程监视。 10 /* in tsk->exit_state */ 11 #define EXIT_ZOMBIE 16 //EXIT_ZOMBIE表示进程的执行被终止，但是其父进程还没有使用wait()等系统调用来获知它的终止信息。 12 #define EXIT_DEAD 32 EXIT_DEAD表示进程的最终状态。 13 /* in tsk->state again */ 14 #define TASK_DEAD 64 15 #define TASK_WAKEKILL 128 16 #define TASK_WAKING 256 17 /*EXIT_ZOMBIE和EXIT_DEAD也可以存放在exit_state成员中。*/

 1 int prio;static_prio, normal_prio; 
 2  /*prio用于保存动态优先级。  3 static_prio用于保存静态优先级，可以通过nice系统调用来进行修改。
 normal_prio的值取决于静态优先级和调度策略。*/  4 unsigned int rt_priority; //表示此进程的运行优先级  5 const struct sched_class *sched_class; // sched_class结构体表示调度类  6 struct sched_entity se;  7 struct sched_rt_entity rt;  8 /*se和rt都是调用实体，一个用于普通进程，一个用于实时进程，每个进程都有其中之一的实体。*/  9 unsigned int policy; // policy表示进程的调度策略 10 cpumask_t cpus_allowed;// cpus_allowed用于控制进程可以在哪里处理器上运行。 11 // policy表示进程的调度策略，目前主要有以下五种： 12 #define SCHED_NORMAL 0 //SCHED_NORMAL用于普通进程，通过CFS调度器实现。 13 #define SCHED_FIFO 1 14 #define SCHED_RR 2 15 // SCHED_FIFO（先入先出调度算法）和SCHED_RR（轮流调度算法）都是实时调度策略。 16 #define SCHED_BATCH 3 //SCHED_BATCH用于非交互的处理器消耗型进程。 17 /* SCHED_ISO: reserved but not implemented yet */ 18 #define SCHED_IDLE 5 //SCHED_IDLE是在系统负载很低时使用。 19 //sched_class结构体表示调度类，目前内核中有实现以下四种： 20 /* linux-2.6.38.8/kernel/sched_fair.c */ 21 static const struct sched_class fair_sched_class; 22 /* linux-2.6.38.8/kernel/sched_rt.c */ 23 static const struct sched_class rt_sched_class; 24 /* linux-2.6.38.8/kernel/sched_idletask.c */ 25 static const struct sched_class idle_sched_class; 26 /* linux-2.6.38.8/kernel/sched_stoptask.c */ 27 static const struct sched_class stop_sched_class; 

1 struct task_struct *real_parent; /* real parent process ，real_parent指向其父进程，如果创建它的父进程不再存在，则指向PID为1的init进程。 */  
2 struct task_struct *parent; /* recipient of SIGCHLD, wait4() reports， parent指向其父进程，当它终止时，必须向它的父进程发送信号。它的值通常与real_parent相同。 */ 3 struct list_head children; /* list of my children， children表示链表的头部，链表中的所有元素都是它的子进程。 */ 4 struct list_head sibling; /* linkage in my parent's children list， sibling用于把当前进程插入到兄弟链表中。 */ 5 struct task_struct *group_leader; /* threadgroup leader ，group_leader指向其所在进程组的领头进程。*/ 

 1 unsigned int flags; /* per process flags, defined below */  
 2 // flags成员的可能取值如下：  3 #define PF_KSOFTIRQD 0x00000001 /* I am ksoftirqd */  4 #define PF_STARTING 0x00000002 /* being created */  5 #define PF_EXITING 0x00000004 /* getting shut down */  6 #define PF_EXITPIDONE 0x00000008 /* pi exit done on shut down */  7 #define PF_VCPU 0x00000010 /* I'm a virtual CPU */  8 #define PF_WQ_WORKER 0x00000020 /* I'm a workqueue worker */  9 #define PF_FORKNOEXEC 0x00000040 /* forked but didn't exec */ 10 #define PF_MCE_PROCESS 0x00000080 /* process policy on mce errors */ 11 #define PF_SUPERPRIV 0x00000100 /* used super-user privileges */ 12 #define PF_DUMPCORE 0x00000200 /* dumped core */ 13 #define PF_SIGNALED 0x00000400 /* killed by a signal */ 14 #define PF_MEMALLOC 0x00000800 /* Allocating memory */ 15 #define PF_USED_MATH 0x00002000 /* if unset the fpu must be initialized before use */ 16 #define PF_FREEZING 0x00004000 /* freeze in progress. do not account to load */ 17 #define PF_NOFREEZE 0x00008000 /* this thread should not be frozen */ 18 #define PF_FROZEN 0x00010000 /* frozen for system suspend */ 19 #define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */ 20 #define PF_KSWAPD 0x00040000 /* I am kswapd */ 21 #define PF_OOM_ORIGIN 0x00080000 /* Allocating much memory to others */ 22 #define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */ 23 #define PF_KTHREAD 0x00200000 /* I am a kernel thread */ 24 #define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */ 25 #define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ 26 #define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */ 27 #define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */ 28 #define PF_THREAD_BOUND 0x04000000 /* Thread bound to specific cpu */ 29 #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ 30 #define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */ 31 #define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */ 32 #define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezable */ 33 #define PF_FREEZER_NOSIG 0x80000000 /* Freezer won't send signals to it */ 

 1 void *stack; 
 2 //
 3 /* linux-2.6.38.8/kernel/fork.c */  4 static inline struct thread_info *alloc_thread_info(struct task_struct *tsk)  5 {  6 #ifdef CONFIG_DEBUG_STACK_USAGE  7 gfp_t mask = GFP_KERNEL | __GFP_ZERO;  8 #else  9 gfp_t mask = GFP_KERNEL; 10 #endif 11 return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER); 12 } 13 static inline void free_thread_info(struct thread_info *ti) 14 { 15 free_pages((unsigned long)ti, THREAD_SIZE_ORDER); 16 } 17 /*其中，THREAD_SIZE_ORDER宏在linux-2.6.38.8/arch/arm/include/asm/thread_info.h文件中被定义为1，也就是说alloc_thread_info函数通过调用__get_free_pages函数分配2个页的内存（它的首地址是8192字节对齐的）。 18 19  Linux内核通过thread_union联合体来表示进程的内核栈，其中THREAD_SIZE宏的大小为8192。 */ 20 union thread_union { 21 struct thread_info thread_info; 22 unsigned long stack[THREAD_SIZE/sizeof(long)]; 23 }; 24 /*当进程从用户态切换到内核态时，进程的内核栈总是空的，所以ARM的sp寄存器指向这个栈的顶端。因此，内核能够轻易地通过sp寄存器获得当前正在CPU上运行的进程。*/ 25 /* linux-2.6.38.8/arch/arm/include/asm/current.h */ 26 static inline struct task_struct *get_current(void) 27 { 28 return current_thread_info()->task; 29 } 30 31 #define current (get_current()) 32 33 /* linux-2.6.38.8/arch/arm/include/asm/thread_info.h */ 34 static inline struct thread_info *current_thread_info(void) 35 { 36 register unsigned long sp asm ("sp"); 37 return (struct thread_info *)(sp & ~(THREAD_SIZE - 1)); 38 } 

 1 unsigned int ptrace;  
 2 struct list_head ptraced;  3 struct list_head ptrace_entry;  4 unsigned long ptrace_message;  5 siginfo_t *last_siginfo; /* For ptrace use. */  6 ifdef CONFIG_HAVE_HW_BREAKPOINT  7 atomic_t ptrace_bp_refcnt;  8 endif  9 /*成员ptrace被设置为0时表示不需要被跟踪，它的可能取值如下：*/ 10 /* linux-2.6.38.8/include/linux/ptrace.h */ 11 #define PT_PTRACED 0x00000001 12 #define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ 13 #define PT_TRACESYSGOOD 0x00000004 14 #define PT_PTRACE_CAP 0x00000008 /* ptracer can follow suid-exec */ 15 #define PT_TRACE_FORK 0x00000010 16 #define PT_TRACE_VFORK 0x00000020 17 #define PT_TRACE_CLONE 0x00000040 18 #define PT_TRACE_EXEC 0x00000080 19 #define PT_TRACE_VFORK_DONE 0x00000100 20 #define PT_TRACE_EXIT 0x00000200 

1 #ifdef CONFIG_PERF_EVENTS  
2     struct perf_event_context *perf_event_ctxp[perf_nr_task_contexts];  
3 struct mutex perf_event_mutex; 4 struct list_head perf_event_list; 5 #endif 

 1 int exit_code, exit_signal;  
 2 /*exit_code用于设置进程的终止代号，这个值要么是_exit()或exit_group()系统调用参数（正常终止），要么是由内核提供的一个错误代号（异常终止）。  3 exit_signal被置为-1时表示是某个线程组中的一员。只有当线程组的最后一个成员终止时，才会产生一个信号，以通知线程组的领头进程的父进程。*/  4 int pdeath_signal; /* The signal sent when the parent dies */  5 /* pdeath_signal用于判断父进程终止时发送信号。 */  6 unsigned int personality; // personality用于处理不同的ABI  7 unsigned did_exec:1; // did_exec用于记录进程代码是否被execve()函数所执行。  8 unsigned in_execve:1; /* Tell the LSMs that the process is doing an * execve */  9 // in_execve用于通知LSM是否被do_execve()函数所调用。 10 unsigned in_iowait:1; // in_iowait用于判断是否进行iowait计数。 11 /* Revert to default priority/policy when forking */ 12 unsigned sched_reset_on_fork:1; // sched_reset_on_fork用于判断是否恢复默认的优先级或调度策略。 13 // personality用于处理不同的ABI，它的可能取值如下： 14 enum { 15 PER_LINUX = 0x0000, 16 PER_LINUX_32BIT = 0x0000 | ADDR_LIMIT_32BIT, 17 PER_LINUX_FDPIC = 0x0000 | FDPIC_FUNCPTRS, 18 PER_SVR4 = 0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, 19 PER_SVR3 = 0x0002 | STICKY_TIMEOUTS | SHORT_INODE, 20 PER_SCOSVR3 = 0x0003 | STICKY_TIMEOUTS | 21 WHOLE_SECONDS | SHORT_INODE, 22 PER_OSR5 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS, 23 PER_WYSEV386 = 0x0004 | STICKY_TIMEOUTS | SHORT_INODE, 24 PER_ISCR4 = 0x0005 | STICKY_TIMEOUTS, 25 PER_BSD = 0x0006, 26 PER_SUNOS = 0x0006 | STICKY_TIMEOUTS, 27 PER_XENIX = 0x0007 | STICKY_TIMEOUTS | SHORT_INODE, 28 PER_LINUX32 = 0x0008, 29 PER_LINUX32_3GB = 0x0008 | ADDR_LIMIT_3GB, 30 PER_IRIX32 = 0x0009 | STICKY_TIMEOUTS,/* IRIX5 32-bit */ 31 PER_IRIXN32 = 0x000a | STICKY_TIMEOUTS,/* IRIX6 new 32-bit */ 32 PER_IRIX64 = 0x000b | STICKY_TIMEOUTS,/* IRIX6 64-bit */ 33 PER_RISCOS = 0x000c, 34 PER_SOLARIS = 0x000d | STICKY_TIMEOUTS, 35 PER_UW7 = 0x000e | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, 36 PER_OSF4 = 0x000f, /* OSF/1 v4 */ 37 PER_HPUX = 0x0010, 38 PER_MASK = 0x00ff, 39 }; 

 1 cputime_t utime, stime, utimescaled, stimescaled;  /* utime/stime用于记录进程在用户态/内核态下所经过的节拍数（定时器）。 utimescaled/stimescaled也是用于记录进程在用户态/内核态的运行时间，但它们以处理器的频率为刻度。*/
 2     cputime_t gtime;  // gtime是以节拍计数的虚拟机运行时间（guest time）。  3 #ifndef CONFIG_VIRT_CPU_ACCOUNTING  4 cputime_t prev_utime, prev_stime; //prev_utime/prev_stime是先前的运行时间  5 #endif  6 unsigned long nvcsw, nivcsw; /* context switch counts */  7 /*nvcsw/nivcsw是自愿（voluntary）/非自愿（involuntary）上下文切换计数。*/  8 struct timespec start_time; /* monotonic time */  9 struct timespec real_start_time; /* boot based time */ 10 /*start_time和real_start_time都是进程创建时间，real_start_time还包含了进程睡眠时间，常用于/proc/pid/stat*/ 11 struct task_cputime cputime_expires; //cputime_expires用来统计进程或进程组被跟踪的处理器时间，其中的三个成员对应着cpu_timers[3]的三个链表。 12 struct list_head cpu_timers[3]; 13 #ifdef CONFIG_DETECT_HUNG_TASK 14 /* hung task detection */ 15 unsigned long last_switch_count; //last_switch_count是nvcsw和nivcsw的总和。 16 #endif 

1  struct mm_struct *mm, *active_mm;  
2 /* mm指向进程所拥有的内存描述符，而active_mm指向进程运行时所使用的内存描述符。对于普通进程而言，这两个指针变量的值相同。但是，内核线程不拥有任何内存描述符，所以它们的mm成员总是为NULL。当内核线程得以运行时，它的active_mm成员被初始化为前一个运行进程的active_mm值。*/ 3 #ifdef CONFIG_COMPAT_BRK 4 unsigned brk_randomized:1; // brk_randomized 用来确定对随机堆内存的探测。 5 #endif 6 #if defined(SPLIT_RSS_COUNTING) 7 struct task_rss_stat rss_stat; // rss_stat用来记录缓冲信息。 8 #endif 

 1 /* signal handlers */  
 2     struct signal_struct *signal; //signal指向进程的信号描述符。  3 struct sighand_struct *sighand; sighand指向进程的信号处理程序描述符。  4 sigset_t blocked, real_blocked; //blocked表示被阻塞信号的掩码，real_blocked表示临时掩码。  5 sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */  6 struct sigpending pending; //pending存放私有挂起信号的数据结构。  7 unsigned long sas_ss_sp; //sas_ss_sp是信号处理程序备用堆栈的地址，sas_ss_size表示堆栈的大小。  8  size_t sas_ss_size;  9 int (*notifier)(void *priv); 10 void *notifier_data; 11 sigset_t *notifier_mask; 12 /*设备驱动程序常用notifier指向的函数来阻塞进程的某些信号（notifier_mask是这些信号的位掩码），notifier_data指的是notifier所指向的函数可能使用的数据。*/

  1 /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, 
  2  * mempolicy */  3 spinlock_t alloc_lock; //用于保护资源分配或释放的自旋锁  4  5 atomic_t usage; //进程描述符使用计数，被置为2时，表示进程描述符正在被使用而且其相应的进程处于活动状态。  6  7 int lock_depth; /* BKL lock depth 用于表示获取大内核锁的次数，如果进程未获得过锁，则置为-1。*/  8  9 #ifdef CONFIG_SMP  10 #ifdef __ARCH_WANT_UNLOCKED_CTXSW  11 int oncpu; //在SMP上帮助实现无加锁的进程切换（unlocked context switches）  12 #endif  13 #endif  14  15  #ifdef CONFIG_PREEMPT_NOTIFIERS  16 /* list of struct preempt_notifier: */  17 struct hlist_head preempt_notifiers; //preempt_notifier结构体链表  18 #endif  19  20 unsigned char fpu_counter; //FPU使用计数  21  22 #ifdef CONFIG_BLK_DEV_IO_TRACE  23 unsigned int btrace_seq; //blktrace是一个针对Linux内核中块设备I/O层的跟踪工具。  24 #endif  25  26 #ifdef CONFIG_PREEMPT_RCU  27 int rcu_read_lock_nesting;  28 char rcu_read_unlock_special;  29 struct list_head rcu_node_entry;  30 #endif /* #ifdef CONFIG_PREEMPT_RCU */  31 #ifdef CONFIG_TREE_PREEMPT_RCU  32 struct rcu_node *rcu_blocked_node;  33 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */  34 #ifdef CONFIG_RCU_BOOST  35 struct rt_mutex *rcu_boost_mutex;  36 #endif /* #ifdef CONFIG_RCU_BOOST */  37 //RCU同步原语  38  39 #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)  40 struct sched_info sched_info; //用于调度器统计进程的运行信息  41 #endif  42  43 struct list_head tasks; // 用于构建进程链表  44  45 #ifdef CONFIG_SMP  46 struct plist_node pushable_tasks; //to limit pushing to one attempt  47 #endif  48  49 #ifdef CONFIG_CC_STACKPROTECTOR  50 /* Canary value for the -fstack-protector gcc feature */  51 unsigned long stack_canary; // 在GCC编译内核时，需要加上-fstack-protector选项。  52 #endif  53  54 /* PID/PID hash table linkage. */  55 struct pid_link pids[PIDTYPE_MAX]; //PID散列表和链表  56 struct list_head thread_group; //线程组中所有进程的链表  57  58 struct completion *vfork_done; /* for vfork() */ //do_fork函数  59 int __user *set_child_tid; /* CLONE_CHILD_SETTID */  60 int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */  61 /*在执行do_fork()时，如果给定特别标志，则vfork_done会指向一个特殊地址. 如果copy_process函数的clone_flags参数的值被置为CLONE_CHILD_SETTID或CLONE_CHILD_CLEARTID，则会把child_tidptr参数的值分别复制到set_child_tid和clear_child_tid成员。这些标志说明必须改变子进程用户态地址空间的child_tidptr所指向的变量的值。*/  62  63 /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */  64 unsigned long min_flt, maj_flt;//缺页统计  65  66 const struct cred __rcu *real_cred; /* objective and real subjective task  67  * credentials (COW) */  68 const struct cred __rcu *cred; /* effective (overridable) subjective task  69  * credentials (COW) */  70 struct cred *replacement_session_keyring;  71 /* for KEYCTL_SESSION_TO_PARENT */  72 //const struct cred __rcu *real_cred; /* objective and real subjective task  73 * credentials (COW) */ 74 const struct cred __rcu *cred; /* effective (overridable) subjective task 75 * credentials (COW) */ 76 struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */ 77 const struct cred __rcu *real_cred; /* objective and real subjective task 78 * credentials (COW) */ 79 const struct cred __rcu *cred; /* effective (overridable) subjective task 80 * credentials (COW) */ 81 struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */ 82 进程权能 83 84 char comm[TASK_COMM_LEN]; //相应的程序名 85 86 /* file system info */ 87 int link_count, total_link_count; 88 /* filesystem information */ 89 struct fs_struct *fs; //fs用来表示进程与文件系统的联系，包括当前目录和根目录。 90 /* open file information */ 91 struct files_struct *files; //files表示进程当前打开的文件。 92 //文件 93 94 #ifdef CONFIG_SYSVIPC 95 /* ipc stuff */ 96 struct sysv_sem sysvsem; 进程通信（SYSVIPC） 97 #endif 98 99 /* CPU-specific state of this task */ 100 struct thread_struct thread;//处理器特有数据 101 102 /* namespaces */ 103 struct nsproxy *nsproxy; //命名空间 104 105 /* namespaces */ 106 struct nsproxy *nsproxy; //命名空间 107 108 struct audit_context *audit_context; 109 #ifdef CONFIG_AUDITSYSCALL 110 uid_t loginuid; 111 unsigned int sessionid; 112 #endif 113 //进程审计 114 115 seccomp_t seccomp; //secure computing 116 117 /* Thread group tracking */ 118 u32 parent_exec_id; 119 u32 self_exec_id; 120 //用于copy_process函数使用CLONE_PARENT 标记时 121 122 //中断 123 #ifdef CONFIG_GENERIC_HARDIRQS 124 /* IRQ handler threads */ 125 struct irqaction *irqaction; 126 #endif 127 #ifdef CONFIG_TRACE_IRQFLAGS 128 unsigned int irq_events; 129 unsigned long hardirq_enable_ip; 130 unsigned long hardirq_disable_ip; 131 unsigned int hardirq_enable_event; 132 unsigned int hardirq_disable_event; 133 int hardirqs_enabled; 134 int hardirq_context; 135 unsigned long softirq_disable_ip; 136 unsigned long softirq_enable_ip; 137 unsigned int softirq_disable_event; 138 unsigned int softirq_enable_event; 139 int softirqs_enabled; 140 int softirq_context; 141 #endif 142 143 /* Protection of the PI data structures: */ 144 raw_spinlock_t pi_lock; //task_rq_lock函数所使用的锁 145 146 //基于PI协议的等待互斥锁，其中PI指的是priority inheritance（优先级继承） 147 #ifdef CONFIG_RT_MUTEXES 148 /* PI waiters blocked on a rt_mutex held by this task */ 149 struct plist_head pi_waiters; 150 /* Deadlock detection and priority inheritance handling */ 151 struct rt_mutex_waiter *pi_blocked_on; 152 #endif 153 154 #ifdef CONFIG_DEBUG_MUTEXES 155 /* mutex deadlock detection */ 156 struct mutex_waiter *blocked_on; //死锁检测 157 #endif 158 159 //lockdep，参见内核说明文档linux-2.6.38.8/Documentation/lockdep-design.txt 160 #ifdef CONFIG_LOCKDEP 161 # define MAX_LOCK_DEPTH 48UL 162 u64 curr_chain_key; 163 int lockdep_depth; 164 unsigned int lockdep_recursion; 165 struct held_lock held_locks[MAX_LOCK_DEPTH]; 166 gfp_t lockdep_reclaim_gfp; 167 #endif 168 169 /* journalling filesystem info */ 170 void *journal_info; //JFS文件系统 171 172 /* stacked block device info */ 173 struct bio_list *bio_list; //块设备链表 174 175 struct reclaim_state *reclaim_state; //内存回收 176 177 struct backing_dev_info *backing_dev_info; //存放块设备I/O数据流量信息 178 179 struct io_context *io_context; //I/O调度器所使用的信息 180 181 //记录进程的I/O计数 182 struct task_io_accounting ioac; 183 if defined(CONFIG_TASK_XACCT) 184 u64 acct_rss_mem1; /* accumulated rss usage */ 185 u64 acct_vm_mem1; /* accumulated virtual memory usage */ 186 cputime_t acct_timexpd; /* stime + utime since last update */ 187 endif 188 189 //CPUSET功能 190 #ifdef CONFIG_CPUSETS 191 nodemask_t mems_allowed; /* Protected by alloc_lock */ 192 int mems_allowed_change_disable; 193 int cpuset_mem_spread_rotor; 194 int cpuset_slab_spread_rotor; 195 #endif 196 197 //Control Groups 198 #ifdef CONFIG_CGROUPS 199 /* Control Group info protected by css_set_lock */ 200 struct css_set __rcu *cgroups; 201 /* cg_list protected by css_set_lock and tsk->alloc_lock */ 202 struct list_head cg_list; 203 #endif 204 #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */ 205 struct memcg_batch_info { 206 int do_batch; /* incremented when batch uncharge started */ 207 struct mem_cgroup *memcg; /* target memcg of uncharge */ 208 unsigned long bytes; /* uncharged usage */ 209 unsigned long memsw_bytes; /* uncharged mem+swap usage */ 210 } memcg_batch; 211 #endif 212 213 //futex同步机制 214 #ifdef CONFIG_FUTEX 215 struct robust_list_head __user *robust_list; 216 #ifdef CONFIG_COMPAT 217 struct compat_robust_list_head __user *compat_robust_list; 218 #endif 219 struct list_head pi_state_list; 220 struct futex_pi_state *pi_state_cache; 221 #endif 222 223 //非一致内存访问（NUMA Non-Uniform Memory Access） 224 #ifdef CONFIG_NUMA 225 struct mempolicy *mempolicy; /* Protected by alloc_lock */ 226 short il_next; 227 #endif 228 229 atomic_t fs_excl; /* holding fs exclusive resources */ //文件系统互斥资源 230 231 struct rcu_head rcu; //RCU链表 232 233 struct pipe_inode_info *splice_pipe; //管道 234 235 #ifdef CONFIG_TASK_DELAY_ACCT 236 struct task_delay_info *delays; //延迟计数 237 #endif 238 239 #ifdef CONFIG_FAULT_INJECTION 240 int make_it_fail; //fault injection 241 #endif 242 243 struct prop_local_single dirties; //FLoating proportions 244 245 #ifdef CONFIG_LATENCYTOP 246 int latency_record_count; 247 struct latency_record latency_record[LT_SAVECOUNT]; 248 #endif //Infrastructure for displayinglatency 249 250 unsigned long timer_slack_ns; 251 unsigned long default_timer_slack_ns; 252 //time slack values，常用于poll和select函数 253 254 struct list_head *scm_work_list; //socket控制消息（control message） 255 256 //ftrace跟踪器 257 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 258 /* Index of current stored address in ret_stack */ 259 int curr_ret_stack; 260 /* Stack of return addresses for return function tracing */ 261 struct ftrace_ret_stack *ret_stack; 262 /* time stamp for last schedule */ 263 unsigned long long ftrace_timestamp; 264 /* 265 * Number of functions that haven't been traced 266 * because of depth overrun. 267 */ 268 atomic_t trace_overrun; 269 /* Pause for the tracing */ 270 atomic_t tracing_graph_pause; 271 #endif 272 #ifdef CONFIG_TRACING 273 /* state flags for use by tracers */ 274 unsigned long trace; 275 /* bitmask of trace recursion */ 276 unsigned long trace_recursion; 277 #endif /* CONFIG_TRACING */