1、進程狀態
[cpp] view plain copy volatile long state; int exit_state;state成員的可能取值如下：
[cpp] view plain copy #define TASK_RUNNING 0 #define TASK_INTERRUPTIBLE 1 #define TASK_UNINTERRUPTIBLE 2 #define __TASK_STOPPED 4 #define __TASK_TRACED 8 /* in tsk->exit_state */ #define EXIT_ZOMBIE 16 #define EXIT_DEAD 32 /* in tsk->state again */ #define TASK_DEAD 64 #define TASK_WAKEKILL 128 #define TASK_WAKING 256系統中的每個進程都必然處于以上所列進程狀態中的一種。
TASK_RUNNING表示進程要么正在執行，要么正要準備執行。
TASK_INTERRUPTIBLE表示進程被阻塞（睡眠），直到某個條件變為真。條件一旦達成，進程的狀態就被設置為TASK_RUNNING。
TASK_UNINTERRUPTIBLE的意義與TASK_INTERRUPTIBLE類似，除了不能通過接受一個信號來喚醒以外。
__TASK_STOPPED表示進程被停止執行。
__TASK_TRACED表示進程被debugger等進程監視。
EXIT_ZOMBIE表示進程的執行被終止，但是其父進程還沒有使用wait()等系統調用來獲知它的終止信息。
EXIT_DEAD表示進程的最終狀態。
EXIT_ZOMBIE和EXIT_DEAD也可以存放在exit_state成員中。
2、進程標識符（PID）
[cpp] view plain copy pid_t pid; pid_t tgid;在CONFIG_BASE_SMALL配置為0的情況下，PID的取值范圍是0到32767，即系統中的進程數最大為32768個。
[cpp] view plain copy /* linux-2.6.38.8/include/linux/threads.h */ #define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)在Linux系統中，一個線程組中的所有線程使用和該線程組的領頭線程（該組中的第一個輕量級進程）相同的PID，并被存放在tgid成員中。只有線程組的領頭線程的pid成員才會被設置為與tgid相同的值。注意，getpid()系統調用返回的是當前進程的tgid值而不是pid值。
3、進程內核棧
[cpp] view plain copy void *stack;進程通過alloc_thread_info函數分配它的內核棧，通過free_thread_info函數釋放所分配的內核棧。
[cpp] view plain copy /* linux-2.6.38.8/kernel/fork.c */ static inline struct thread_info *alloc_thread_info(struct task_struct *tsk) { #ifdef CONFIG_DEBUG_STACK_USAGE gfp_t mask = GFP_KERNEL | __GFP_ZERO; #else gfp_t mask = GFP_KERNEL; #endif return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER); } static inline void free_thread_info(struct thread_info *ti) { free_pages((unsigned long)ti, THREAD_SIZE_ORDER); }其中，THREAD_SIZE_ORDER宏在linux-2.6.38.8/arch/arm/include/asm/thread_info.h文件中被定義為1，也就是說alloc_thread_info函數通過調用__get_free_pages函數分配2個頁的內存（它的首地址是8192 字節對齊的）。
Linux內核通過thread_union聯合體來表示進程的內核棧，其中THREAD_SIZE宏的大小為8192。
[cpp] view plain copyunion thread_union { struct thread_info thread_info; unsigned long stack[THREAD_SIZE/sizeof(long)]; };當進程從用戶態切換到內核態時，進程的內核棧總是空的，所以ARM的sp寄存器指向這個棧的頂端。因此，內核能夠輕易地通過sp寄存器獲得當前正在CPU上運行的進程。
[cpp] view plain copy /* linux-2.6.38.8/arch/arm/include/asm/current.h */ static inline struct task_struct *get_current(void) { return current_thread_info()->task; } #define current (get_current()) /* linux-2.6.38.8/arch/arm/include/asm/thread_info.h */ static inline struct thread_info *current_thread_info(void) { register unsigned long sp asm ("sp"); return (struct thread_info *)(sp & ~(THREAD_SIZE - 1)); }4、標記
[cpp] view plain copy unsigned int flags; /* per PRocess flags, defined below */flags成員的可能取值如下：
[cpp] view plain copy #define PF_KSOFTIRQD 0x00000001 /* I am ksoftirqd */ #define PF_STARTING 0x00000002 /* being created */ #define PF_EXITING 0x00000004 /* getting shut down */ #define PF_EXITPIDONE 0x00000008 /* pi exit done on shut down */ #define PF_VCPU 0x00000010 /* I'm a virtual CPU */ #define PF_WQ_WORKER 0x00000020 /* I'm a workqueue worker */ #define PF_FORKNOEXEC 0x00000040 /* forked but didn't exec */ #define PF_MCE_PROCESS 0x00000080 /* process policy on mce errors */ #define PF_SUPERPRIV 0x00000100 /* used super-user privileges */ #define PF_DUMPCORE 0x00000200 /* dumped core */ #define PF_SIGNALED 0x00000400 /* killed by a signal */ #define PF_MEMALLOC 0x00000800 /* Allocating memory */ #define PF_USED_MATH 0x00002000 /* if unset the fpu must be initialized before use */ #define PF_FREEZING 0x00004000 /* freeze in progress. do not account to load */ #define PF_NOFREEZE 0x00008000 /* this thread should not be frozen */ #define PF_FROZEN 0x00010000 /* frozen for system suspend */ #define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */ #define PF_KSWAPD 0x00040000 /* I am kswapd */ #define PF_OOM_ORIGIN 0x00080000 /* Allocating much memory to others */ #define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */ #define PF_KTHREAD 0x00200000 /* I am a kernel thread */ #define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */ #define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ #define PF_SPREAD_PAGE 0x01000000 /* Spread page cache over cpuset */ #define PF_SPREAD_SLAB 0x02000000 /* Spread some slab caches over cpuset */ #define PF_THREAD_BOUND 0x04000000 /* Thread bound to specific cpu */ #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ #define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */ #define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */ #define PF_FREEZER_SK 5、表示進程親屬關系的成員 [cpp] view plain copy struct task_struct *real_parent; /* real parent process */ struct task_struct *parent; /* recipient of SIGCHLD, wait4() reports */ struct list_head children; /* list of my children */ struct list_head sibling; /* linkage in my parent's children list */ struct task_struct *group_leader; /* threadgroup leader */在Linux系統中，所有進程之間都有著直接或間接地聯系，每個進程都有其父進程，也可能有零個或多個子進程。擁有同一父進程的所有進程具有兄弟關系。
real_parent指向其父進程，如果創建它的父進程不再存在，則指向PID為1的init進程。
parent指向其父進程，當它終止時，必須向它的父進程發送信號。它的值通常與real_parent相同。
children表示鏈表的頭部，鏈表中的所有元素都是它的子進程。
sibling用于把當前進程插入到兄弟鏈表中。
group_leader指向其所在進程組的領頭進程。
6、ptrace系統調用
[cpp] view plain copy unsigned int ptrace; struct list_head ptraced; struct list_head ptrace_entry; unsigned long ptrace_message; siginfo_t *last_siginfo; /* For ptrace use. */ ifdef CONFIG_HAVE_HW_BREAKPOINT atomic_t ptrace_bp_refcnt; endif成員ptrace被設置為0時表示不需要被跟蹤，它的可能取值如下：
[cpp] view plain copy /* linux-2.6.38.8/include/linux/ptrace.h */ #define PT_PTRACED 0x00000001 #define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */ #define PT_TRACESYSGOOD 0x00000004 #define PT_PTRACE_CAP 0x00000008 /* ptracer can follow suid-exec */ #define PT_TRACE_FORK 0x00000010 #define PT_TRACE_VFORK 0x00000020 #define PT_TRACE_CLONE 0x00000040 #define PT_TRACE_EXEC 0x00000080 #define PT_TRACE_VFORK_DONE 0x00000100 #define PT_TRACE_EXIT 0x000002007、Performance Event
[cpp] view plain copy #ifdef CONFIG_PERF_EVENTS struct perf_event_context *perf_event_ctxp[perf_nr_task_contexts]; struct mutex perf_event_mutex; struct list_head perf_event_list; #endifPerformance Event是一款隨 Linux 內核代碼一同發布和維護的性能診斷工具。這些成員用于幫助PerformanceEvent分析進程的性能問題。
8、進程調度
[cpp] view plain copy int prio, static_prio, normal_prio; unsigned int rt_priority; const struct sched_class *sched_class; struct sched_entity se; struct sched_rt_entity rt; unsigned int policy; cpumask_t cpus_allowed;實時優先級范圍是0到MAX_RT_PRIO-1（即99），而普通進程的靜態優先級范圍是從MAX_RT_PRIO到MAX_PRIO-1（即100到139）。值越大靜態優先級越低。
[cpp] view plain copy/* linux-2.6.38.8/include/linux/sched.h */ #define MAX_USER_RT_PRIO 100 #define MAX_RT_PRIO MAX_USER_RT_PRIO #define MAX_PRIO (MAX_RT_PRIO + 40) #define DEFAULT_PRIO (MAX_RT_PRIO + 20)static_prio用于保存靜態優先級，可以通過nice系統調用來進行修改。
rt_priority用于保存實時優先級。
normal_prio的值取決于靜態優先級和調度策略。
prio用于保存動態優先級。
policy表示進程的調度策略，目前主要有以下五種：
[cpp] view plain copy#define SCHED_NORMAL 0 #define SCHED_FIFO 1 #define SCHED_RR 2 #define SCHED_BATCH 3 /* SCHED_ISO: reserved but not implemented yet */ #define SCHED_IDLE 5SCHED_NORMAL用于普通進程，通過CFS調度器實現。SCHED_BATCH用于非交互的處理器消耗型進程。SCHED_IDLE是在系統負載很低時使用。
SCHED_FIFO（先入先出調度算法）和SCHED_RR（輪流調度算法）都是實時調度策略。
sched_class結構體表示調度類，目前內核中有實現以下四種：
[cpp] view plain copy/* linux-2.6.38.8/kernel/sched_fair.c */ static const struct sched_class fair_sched_class; /* linux-2.6.38.8/kernel/sched_rt.c */ static const struct sched_class rt_sched_class; /* linux-2.6.38.8/kernel/sched_idletask.c */ static const struct sched_class idle_sched_class; /* linux-2.6.38.8/kernel/sched_stoptask.c */ static const struct sched_class stop_sched_class;se和rt都是調用實體，一個用于普通進程，一個用于實時進程，每個進程都有其中之一的實體。
cpus_allowed用于控制進程可以在哪里處理器上運行。
9、進程地址空間
[cpp] view plain copy struct mm_struct *mm, *active_mm; #ifdef CONFIG_COMPAT_BRK unsigned brk_randomized:1; #endif #if defined(SPLIT_rss_COUNTING) struct task_rss_stat rss_stat; #endifmm指向進程所擁有的內存描述符，而active_mm指向進程運行時所使用的內存描述符。對于普通進程而言，這兩個指針變量的值相同。但是，內核線程不擁有任何內存描述符，所以它們的mm成員總是為NULL。當內核線程得以運行時，它的active_mm成員被初始化為前一個運行進程的 active_mm值。
rss_stat用來記錄緩沖信息。
10、判斷標志
[cpp] view plain copy int exit_code, exit_signal; int pdeath_signal; /* The signal sent when the parent dies */ /* ??? */ unsigned int personality; unsigned did_exec:1; unsigned in_execve:1; /* Tell the LSMs that the process is doing an * execve */ unsigned in_iowait:1; /* Revert to default priority/policy when forking */ unsigned sched_reset_on_fork:1;exit_code用于設置進程的終止代號，這個值要么是_exit()或exit_group()系統調用參數（正常終止），要么是由內核提供的一個錯誤代號（異常終止）。
exit_signal被置為-1時表示是某個線程組中的一員。只有當線程組的最后一個成員終止時，才會產生一個信號，以通知線程組的領頭進程的父進程。
pdeath_signal用于判斷父進程終止時發送信號。
personality用于處理不同的ABI，它的可能取值如下：
[cpp] view plain copy enum { PER_LINUX = 0x0000, PER_LINUX_32BIT = 0x0000 | ADDR_LIMIT_32BIT, PER_LINUX_FDPIC = 0x0000 | FDPIC_FUNCPTRS, PER_SVR4 = 0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, PER_SVR3 = 0x0002 | STICKY_TIMEOUTS | SHORT_INODE, PER_SCOSVR3 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS | SHORT_INODE, PER_OSR5 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS, PER_WYSEV386 = 0x0004 | STICKY_TIMEOUTS | SHORT_INODE, PER_ISCR4 = 0x0005 | STICKY_TIMEOUTS, PER_BSD = 0x0006, PER_SUNOS = 0x0006 | STICKY_TIMEOUTS, PER_XENIX = 0x0007 | STICKY_TIMEOUTS | SHORT_INODE, PER_LINUX32 = 0x0008, PER_LINUX32_3GB = 0x0008 | ADDR_LIMIT_3GB, PER_IRIX32 = 0x0009 | STICKY_TIMEOUTS,/* IRIX5 32-bit */ PER_IRIXN32 = 0x000a | STICKY_TIMEOUTS,/* IRIX6 new 32-bit */ PER_IRIX64 = 0x000b | STICKY_TIMEOUTS,/* IRIX6 64-bit */ PER_RISCOS = 0x000c, PER_SOLARIS = 0x000d | STICKY_TIMEOUTS, PER_UW7 = 0x000e | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, PER_OSF4 = 0x000f, /* OSF/1 v4 */ PER_HPUX = 0x0010, PER_MASK = 0x00ff, };did_exec用于記錄進程代碼是否被execve()函數所執行。
in_iowait用于判斷是否進行iowait計數。
sched_reset_on_fork用于判斷是否恢復默認的優先級或調度策略。
11、時間
[cpp] view plain copy cputime_t utime, stime, utimescaled, stimescaled; cputime_t gtime; #ifndef CONFIG_VIRT_CPU_ACCOUNTING cputime_t prev_utime, prev_stime; #endif unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; /* monotonic time */ struct timespec real_start_time; /* boot based time */ struct task_cputime cputime_expires; struct list_head cpu_timers[3]; #ifdef CONFIG_DETECT_HUNG_TASK /* hung task detection */ unsigned long last_switch_count; #endifutime/stime用于記錄進程在用戶態/內核態下所經過的節拍數（定時器）
utimescaled/stimescaled也是用于記錄進程在用戶態/內核態的運行時間，但它們以處理器的頻率為刻度。
gtime是以節拍計數的虛擬機運行時間（guest time）。
nvcsw/nivcsw是自愿（voluntary）/非自愿（involuntary）上下文切換計數。last_switch_count是nvcsw和nivcsw的總和。
start_time和real_start_time都是進程創建時間，real_start_time還包含了進程睡眠時間，常用于/proc/pid/stat，
cputime_expires用來統計進程或進程組被跟蹤的處理器時間，其中的三個成員對應著cpu_timers[3]的三個鏈表。
12、信號處理
[cpp] view plain copy /* signal handlers */ struct signal_struct *signal; struct sighand_struct *sighand; sigset_t blocked, real_blocked; sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */ struct sigpending pending; unsigned long sas_ss_sp; size_t sas_ss_size; int (*notifier)(void *priv); void *notifier_data; sigset_t *notifier_mask;signal指向進程的信號描述符。
sighand指向進程的信號處理程序描述符。
blocked表示被阻塞信號的掩碼，real_blocked表示臨時掩碼。
pending存放私有掛起信號的數據結構。
sas_ss_sp是信號處理程序備用堆棧的地址，sas_ss_size表示堆棧的大小。
設備驅動程序常用notifier指向的函數來阻塞進程的某些信號（notifier_mask是這些信號的位掩碼），notifier_data指的是notifier所指向的函數可能使用的數據。
13、其他
（1）、用于保護資源分配或釋放的自旋鎖
[cpp] view plain copy /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, * mempolicy */ spinlock_t alloc_lock;（2）、進程描述符使用計數，被置為2時，表示進程描述符正在被使用而且其相應的進程處于活動狀態。
[cpp] view plain copy atomic_t usage;（3）、用于表示獲取大內核鎖的次數，如果進程未獲得過鎖，則置為-1。
[cpp] view plain copy int lock_depth; /* BKL lock depth */（4）、在SMP上幫助實現無加鎖的進程切換（unlocked context switches）
[cpp] view plain copy #ifdef CONFIG_SMP #ifdef __ARCH_WANT_UNLOCKED_CTXSW int oncpu; #endif #endif（5）、preempt_notifier結構體鏈表
[cpp] view plain copy #ifdef CONFIG_PREEMPT_NOTIFIERS /* list of struct preempt_notifier: */ struct hlist_head preempt_notifiers; #endif（6）、FPU使用計數
[cpp] view plain copy unsigned char fpu_counter;（7）、blktrace是一個針對Linux內核中塊設備I/O層的跟蹤工具。
[cpp] view plain copy #ifdef CONFIG_BLK_DEV_IO_TRACE unsigned int btrace_seq; #endif（8）、RCU同步原語
[cpp] view plain copy #ifdef CONFIG_PREEMPT_RCU int rcu_read_lock_nesting; char rcu_read_unlock_special; struct list_head rcu_node_entry; #endif /* #ifdef CONFIG_PREEMPT_RCU */ #ifdef CONFIG_TREE_PREEMPT_RCU struct rcu_node *rcu_blocked_node; #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ #ifdef CONFIG_RCU_BOOST struct rt_mutex *rcu_boost_mutex; #endif /* #ifdef CONFIG_RCU_BOOST */（9）、用于調度器統計進程的運行信息
[cpp] view plain copy #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif（10）、用于構建進程鏈表
[cpp] view plain copy struct list_head tasks;（11）、to limit pushing to one attempt
[cpp] view plain copy #ifdef CONFIG_SMP struct plist_node pushable_tasks; #endif（12）、防止內核堆棧溢出
[cpp] view plain copy #ifdef CONFIG_CC_STACKPROTECTOR /* Canary value for the -fstack-protector gcc feature */ unsigned long stack_canary; #endif在GCC編譯內核時，需要加上-fstack-protector選項。
（13）、PID散列表和鏈表
[cpp] view plain copy /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; //線程組中所有進程的鏈表（14）、do_fork函數
[cpp] view plain copy struct completion *vfork_done; /* for vfork() */ int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */在執行do_fork()時，如果給定特別標志，則vfork_done會指向一個特殊地址。
如果copy_process函數的clone_flags參數的值被置為CLONE_CHILD_SETTID或 CLONE_CHILD_CLEARTID，則會把child_tidptr參數的值分別復制到set_child_tid和 clear_child_tid成員。這些標志說明必須改變子進程用戶態地址空間的child_tidptr所指向的變量的值。
（15）、缺頁統計
[cpp] view plain copy /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ unsigned long min_flt, maj_flt;（16）、進程權能
[cpp] view plain copy const struct cred __rcu *real_cred; /* objective and real subjective task * credentials (COW) */ const struct cred __rcu *cred; /* effective (overridable) subjective task * credentials (COW) */ struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */（17）、相應的程序名
[cpp] view plain copy char comm[TASK_COMM_LEN];（18）、文件
[cpp] view plain copy /* file system info */ int link_count, total_link_count; /* filesystem information */ struct fs_struct *fs; /* open file information */ struct files_struct *files;fs用來表示進程與文件系統的聯系，包括當前目錄和根目錄。
files表示進程當前打開的文件。
（19）、進程通信（SYSVIPC）
[cpp] view plain copy #ifdef CONFIG_SYSVIPC /* ipc stuff */ struct sysv_sem sysvsem; #endif（20）、處理器特有數據
[cpp] view plain copy /* CPU-specific state of this task */ struct thread_struct thread;（21）、命名空間
[cpp] view plain copy /* namespaces */ struct nsproxy *nsproxy;（22）、進程審計
[cpp] view plain copy struct audit_context *audit_context; #ifdef CONFIG_AUDITSYSCALL uid_t loginuid; unsigned int sessionid; #endif（23）、secure computing
[cpp] view plain copyseccomp_t seccomp;（24）、用于copy_process函數使用CLONE_PARENT 標記時
[cpp] view plain copy/* Thread group tracking */ u32 parent_exec_id; u32 self_exec_id;（25）、中斷
[cpp] view plain copy#ifdef CONFIG_GENERIC_HARDIRQS /* IRQ handler threads */ struct irqaction *irqaction; #endif #ifdef CONFIG_TRACE_IRQFLAGS unsigned int irq_events; unsigned long hardirq_enable_ip; unsigned long hardirq_disable_ip; unsigned int hardirq_enable_event; unsigned int hardirq_disable_event; int hardirqs_enabled; int hardirq_context; unsigned long softirq_disable_ip; unsigned long softirq_enable_ip; unsigned int softirq_disable_event; unsigned int softirq_enable_event; int softirqs_enabled; int softirq_context; #endif（26）、task_rq_lock函數所使用的鎖
[cpp] view plain copy/* Protection of the PI data structures: */ raw_spinlock_t pi_lock;（27）、基于PI協議的等待互斥鎖，其中PI指的是priority inheritance（優先級繼承）
[cpp] view plain copy#ifdef CONFIG_RT_MUTEXES /* PI waiters blocked on a rt_mutex held by this task */ struct plist_head pi_waiters; /* Deadlock detection and priority inheritance handling */ struct rt_mutex_waiter *pi_blocked_on; #endif（28）、死鎖檢測
[cpp] view plain copy#ifdef CONFIG_DEBUG_MUTEXES /* mutex deadlock detection */ struct mutex_waiter *blocked_on; #endif（29）、lockdep，參見內核說明文檔linux-2.6.38.8/Documentation/lockdep-design.txt
[cpp] view plain copy#ifdef CONFIG_LOCKDEP # define MAX_LOCK_DEPTH 48UL u64 curr_chain_key; int lockdep_depth; unsigned int lockdep_recursion; struct held_lock held_locks[MAX_LOCK_DEPTH]; gfp_t lockdep_reclaim_gfp; #endif（30）、JFS文件系統
[cpp] view plain copy/* journalling filesystem info */ void *journal_info;（31）、塊設備鏈表
[cpp] view plain copy/* stacked block device info */ struct bio_list *bio_list;（32）、內存回收
[cpp] view plain copystruct reclaim_state *reclaim_state;（33）、存放塊設備I/O數據流量信息
[cpp] view plain copystruct backing_dev_info *backing_dev_info;（34）、I/O調度器所使用的信息
[cpp] view plain copystruct io_context *io_context;（35）、記錄進程的I/O計數
[cpp] view plain copystruct task_io_accounting ioac; if defined(CONFIG_TASK_XACCT) u64 acct_rss_mem1; /* accumulated rss usage */ u64 acct_vm_mem1; /* accumulated virtual memory usage */ cputime_t acct_timexpd; /* stime + utime since last update */ endif在Ubuntu 11.04上，執行cat獲得進程1的I/O計數如下：
[cpp] view plain copy$ sudo cat /proc/1/io [cpp] view plain copyrchar: 164258906 wchar: 455212837 syscr: 388847 syscw: 92563 read_bytes: 439251968 write_bytes: 14143488 cancelled_write_bytes: 2134016輸出的數據項剛好是task_io_accounting結構體的所有成員。
（36）、CPUSET功能
[cpp] view plain copy#ifdef CONFIG_CPUSETS nodemask_t mems_allowed; /* Protected by alloc_lock */ int mems_allowed_change_disable; int cpuset_mem_spread_rotor; int cpuset_slab_spread_rotor; #endif（37）、Control Groups
[cpp] view plain copy#ifdef CONFIG_CGROUPS /* Control Group info protected by CSS_set_lock */ struct css_set __rcu *cgroups; /* cg_list protected by css_set_lock and tsk->alloc_lock */ struct list_head cg_list; #endif #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */ struct memcg_batch_info { int do_batch; /* incremented when batch uncharge started */ struct mem_cgroup *memcg; /* target memcg of uncharge */ unsigned long bytes; /* uncharged usage */ unsigned long memsw_bytes; /* uncharged mem+swap usage */ } memcg_batch; #endif（38）、futex同步機制
[cpp] view plain copy#ifdef CONFIG_FUTEX struct robust_list_head __user *robust_list; #ifdef CONFIG_COMPAT struct compat_robust_list_head __user *compat_robust_list; #endif struct list_head pi_state_list; struct futex_pi_state *pi_state_cache; #endif（39）、非一致內存訪問（NUMA Non-Uniform Memory access）
[cpp] view plain copy#ifdef CONFIG_NUMA struct mempolicy *mempolicy; /* Protected by alloc_lock */ short il_next; #endif（40）、文件系統互斥資源
[cpp] view plain copyatomic_t fs_excl; /* holding fs exclusive resources */（41）、RCU鏈表
[cpp] view plain copystruct rcu_head rcu;（42）、管道
[cpp] view plain copystruct pipe_inode_info *splice_pipe;（43）、延遲計數
[cpp] view plain copy#ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info *delays; #endif（44）、fault injection
[cpp] view plain copy
#ifdef CONFIG_FAULT_INJECTION int make_it_fail; #endif
（45）、FLoating proportions
[cpp] view plain copystruct prop_local_single dirties;（46）、Infrastructure for displayinglatency
[cpp] view plain copy#ifdef CONFIG_LATENCYTOP int latency_record_count; struct latency_record latency_record[LT_SAVECOUNT]; #endif（47）、time slack values，常用于poll和select函數
[cpp] view plain copyunsigned long timer_slack_ns; unsigned long default_timer_slack_ns;（48）、socket控制消息（control message）
[cpp] view plain copystruct list_head *scm_work_list;（49）、ftrace跟蹤器
[cpp] view plain copy#ifdef CONFIG_FUNCTION_GRAPH_TRACER /* Index of current stored address in ret_stack */ int curr_ret_stack; /* Stack of return addresses for return function tracing */ struct ftrace_ret_stack *ret_stack; /* time stamp for last schedule */ unsigned long long ftrace_timestamp; /* * Number of functions that haven't been traced * because of depth overrun. */ atomic_t trace_overrun; /* Pause for the tracing */ atomic_t tracing_graph_pause; #endif #ifdef CONFIG_TRACING /* state flags for use by tracers */ unsigned long trace; /* bitmask of trace recursion */ unsigned long trace_recursion; #endif /* CONFIG_TRACING */9、進程地址空間
[cpp] view plain copy struct mm_struct *mm, *active_mm; #ifdef CONFIG_COMPAT_BRK unsigned brk_randomized:1; #endif #if defined(SPLIT_RSS_COUNTING) struct task_rss_stat rss_stat; #endifmm指向進程所擁有的內存描述符，而active_mm指向進程運行時所使用的內存描述符。對于普通進程而言，這兩個指針變量的值相同。但是，內核線程不擁有任何內存描述符，所以它們的mm成員總是為NULL。當內核線程得以運行時，它的active_mm成員被初始化為前一個運行進程的 active_mm值。
rss_stat用來記錄緩沖信息。
10、判斷標志
[cpp] view plain copy int exit_code, exit_signal; int pdeath_signal; /* The signal sent when the parent dies */ /* ??? */ unsigned int personality; unsigned did_exec:1; unsigned in_execve:1; /* Tell the LSMs that the process is doing an * execve */ unsigned in_iowait:1; /* Revert to default priority/policy when forking */ unsigned sched_reset_on_fork:1;exit_code用于設置進程的終止代號，這個值要么是_exit()或exit_group()系統調用參數（正常終止），要么是由內核提供的一個錯誤代號（異常終止）。
exit_signal被置為-1時表示是某個線程組中的一員。只有當線程組的最后一個成員終止時，才會產生一個信號，以通知線程組的領頭進程的父進程。
pdeath_signal用于判斷父進程終止時發送信號。
personality用于處理不同的ABI，它的可能取值如下：
[cpp] view plain copy enum { PER_LINUX = 0x0000, PER_LINUX_32BIT = 0x0000 | ADDR_LIMIT_32BIT, PER_LINUX_FDPIC = 0x0000 | FDPIC_FUNCPTRS, PER_SVR4 = 0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, PER_SVR3 = 0x0002 | STICKY_TIMEOUTS | SHORT_INODE, PER_SCOSVR3 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS | SHORT_INODE, PER_OSR5 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS, PER_WYSEV386 = 0x0004 | STICKY_TIMEOUTS | SHORT_INODE, PER_ISCR4 = 0x0005 | STICKY_TIMEOUTS, PER_BSD = 0x0006, PER_SUNOS = 0x0006 | STICKY_TIMEOUTS, PER_XENIX = 0x0007 | STICKY_TIMEOUTS | SHORT_INODE, PER_LINUX32 = 0x0008, PER_LINUX32_3GB = 0x0008 | ADDR_LIMIT_3GB, PER_IRIX32 = 0x0009 | STICKY_TIMEOUTS,/* IRIX5 32-bit */ PER_IRIXN32 = 0x000a | STICKY_TIMEOUTS,/* IRIX6 new 32-bit */ PER_IRIX64 = 0x000b | STICKY_TIMEOUTS,/* IRIX6 64-bit */ PER_RISCOS = 0x000c, PER_SOLARIS = 0x000d | STICKY_TIMEOUTS, PER_UW7 = 0x000e | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, PER_OSF4 = 0x000f, /* OSF/1 v4 */ PER_HPUX = 0x0010, PER_MASK = 0x00ff, };did_exec用于記錄進程代碼是否被execve()函數所執行。
in_execve用于通知LSM是否被do_execve()函數所調用。
in_iowait用于判斷是否進行iowait計數。
sched_reset_on_fork用于判斷是否恢復默認的優先級或調度策略。
11、時間
[cpp] view plain copy cputime_t utime, stime, utimescaled, stimescaled; cputime_t gtime; #ifndef CONFIG_VIRT_CPU_ACCOUNTING cputime_t prev_utime, prev_stime; #endif unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; /* monotonic time */ struct timespec real_start_time; /* boot based time */ struct task_cputime cputime_expires; struct list_head cpu_timers[3]; #ifdef CONFIG_DETECT_HUNG_TASK /* hung task detection */ unsigned long last_switch_count; #endifutime/stime用于記錄進程在用戶態/內核態下所經過的節拍數（定時器）。
utimescaled/stimescaled也是用于記錄進程在用戶態/內核態的運行時間，但它們以處理器的頻率為刻度。
gtime是以節拍計數的虛擬機運行時間（guest time）。
nvcsw/nivcsw是自愿（voluntary）/非自愿（involuntary）上下文切換計數。last_switch_count是nvcsw和nivcsw的總和。
start_time和real_start_time都是進程創建時間，real_start_time還包含了進程睡眠時間，常用于/proc/pid/stat，補丁說明請參考http://lkml.indiana.edu/hypermail/linux/kernel/0705.0/2094.html。
cputime_expires用來統計進程或進程組被跟蹤的處理器時間，其中的三個成員對應著cpu_timers[3]的三個鏈表。
12、信號處理
[cpp] view plain copy /* signal handlers */ struct signal_struct *signal; struct sighand_struct *sighand; sigset_t blocked, real_blocked; sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */ struct sigpending pending; unsigned long sas_ss_sp; size_t sas_ss_size; int (*notifier)(void *priv); void *notifier_data; sigset_t *notifier_mask;signal指向進程的信號描述符。
sighand指向進程的信號處理程序描述符。
blocked表示被阻塞信號的掩碼，real_blocked表示臨時掩碼。
pending存放私有掛起信號的數據結構。
sas_ss_sp是信號處理程序備用堆棧的地址，sas_ss_size表示堆棧的大小。
設備驅動程序常用notifier指向的函數來阻塞進程的某些信號（notifier_mask是這些信號的位掩碼），notifier_data指的是notifier所指向的函數可能使用的數據。
13、其他
（1）、用于保護資源分配或釋放的自旋鎖
[cpp] view plain copy /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, * mempolicy */ spinlock_t alloc_lock;（2）、進程描述符使用計數，被置為2時，表示進程描述符正在被使用而且其相應的進程處于活動狀態。
[cpp] view plain copy atomic_t usage;（3）、用于表示獲取大內核鎖的次數，如果進程未獲得過鎖，則置為-1。
[cpp] view plain copy int lock_depth; /* BKL lock depth */（4）、在SMP上幫助實現無加鎖的進程切換（unlocked context switches）
[cpp] view plain copy #ifdef CONFIG_SMP #ifdef __ARCH_WANT_UNLOCKED_CTXSW int oncpu; #endif #endif（5）、preempt_notifier結構體鏈表
[cpp] view plain copy #ifdef CONFIG_PREEMPT_NOTIFIERS /* list of struct preempt_notifier: */ struct hlist_head preempt_notifiers; #endif（6）、FPU使用計數
[cpp] view plain copy unsigned char fpu_counter;（7）、blktrace是一個針對Linux內核中塊設備I/O層的跟蹤工具。
[cpp] view plain copy #ifdef CONFIG_BLK_DEV_IO_TRACE unsigned int btrace_seq; #endif（8）、RCU同步原語
[cpp] view plain copy #ifdef CONFIG_PREEMPT_RCU int rcu_read_lock_nesting; char rcu_read_unlock_special; struct list_head rcu_node_entry; #endif /* #ifdef CONFIG_PREEMPT_RCU */ #ifdef CONFIG_TREE_PREEMPT_RCU struct rcu_node *rcu_blocked_node; #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ #ifdef CONFIG_RCU_BOOST struct rt_mutex *rcu_boost_mutex; #endif /* #ifdef CONFIG_RCU_BOOST */（9）、用于調度器統計進程的運行信息
[cpp] view plain copy #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif（10）、用于構建進程鏈表
[cpp] view plain copy struct list_head tasks;（11）、to limit pushing to one attempt
[cpp] view plain copy #ifdef CONFIG_SMP struct plist_node pushable_tasks; #endif補丁說明請參考：http://lkml.indiana.edu/hypermail/linux/kernel/0808.3/0503.html
（12）、防止內核堆棧溢出
[cpp] view plain copy #ifdef CONFIG_CC_STACKPROTECTOR /* Canary value for the -fstack-protector gcc feature */ unsigned long stack_canary; #endif在GCC編譯內核時，需要加上-fstack-protector選項。
（13）、PID散列表和鏈表
[cpp] view plain copy /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; //線程組中所有進程的鏈表（14）、do_fork函數
[cpp] view plain copy struct completion *vfork_done; /* for vfork() */ int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */在執行do_fork()時，如果給定特別標志，則vfork_done會指向一個特殊地址。
如果copy_process函數的clone_flags參數的值被置為CLONE_CHILD_SETTID或 CLONE_CHILD_CLEARTID，則會把child_tidptr參數的值分別復制到set_child_tid和 clear_child_tid成員。這些標志說明必須改變子進程用戶態地址空間的child_tidptr所指向的變量的值。
（15）、缺頁統計
[cpp] view plain copy /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ unsigned long min_flt, maj_flt;（16）、進程權能
[cpp] view plain copy const struct cred __rcu *real_cred; /* objective and real subjective task * credentials (COW) */ const struct cred __rcu *cred; /* effective (overridable) subjective task * credentials (COW) */ struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */（17）、相應的程序名
[cpp] view plain copy char comm[TASK_COMM_LEN];（18）、文件
[cpp] view plain copy /* file system info */ int link_count, total_link_count; /* filesystem information */ struct fs_struct *fs; /* open file information */ struct files_struct *files;fs用來表示進程與文件系統的聯系，包括當前目錄和根目錄。
files表示進程當前打開的文件。
（19）、進程通信（SYSVIPC）
[cpp] view plain copy #ifdef CONFIG_SYSVIPC /* ipc stuff */ struct sysv_sem sysvsem; #endif（20）、處理器特有數據
[cpp] view plain copy /* CPU-specific state of this task */ struct thread_struct thread;（21）、命名空間
[cpp] view plain copy /* namespaces */ struct nsproxy *nsproxy;（22）、進程審計
[cpp] view plain copy struct audit_context *audit_context; #ifdef CONFIG_AUDITSYSCALL uid_t loginuid; unsigned int sessionid; #endif（23）、secure computing
[cpp] view plain copyseccomp_t seccomp;（24）、用于copy_process函數使用CLONE_PARENT 標記時
[cpp] view plain copy/* Thread group tracking */ u32 parent_exec_id; u32 self_exec_id;（25）、中斷
[cpp] view plain copy#ifdef CONFIG_GENERIC_HARDIRQS /* IRQ handler threads */ struct irqaction *irqaction; #endif #ifdef CONFIG_TRACE_IRQFLAGS unsigned int irq_events; unsigned long hardirq_enable_ip; unsigned long hardirq_disable_ip; unsigned int hardirq_enable_event; unsigned int hardirq_disable_event; int hardirqs_enabled; int hardirq_context; unsigned long softirq_disable_ip; unsigned long softirq_enable_ip; unsigned int softirq_disable_event; unsigned int softirq_enable_event; int softirqs_enabled; int softirq_context; #endif（26）、task_rq_lock函數所使用的鎖
[cpp] view plain copy/* Protection of the PI data structures: */ raw_spinlock_t pi_lock;（27）、基于PI協議的等待互斥鎖，其中PI指的是priority inheritance（優先級繼承）
[cpp] view plain copy#ifdef CONFIG_RT_MUTEXES /* PI waiters blocked on a rt_mutex held by this task */ struct plist_head pi_waiters; /* Deadlock detection and priority inheritance handling */ struct rt_mutex_waiter *pi_blocked_on; #endif（28）、死鎖檢測
[cpp] view plain copy#ifdef CONFIG_DEBUG_MUTEXES /* mutex deadlock detection */ struct mutex_waiter *blocked_on; #endif（29）、lockdep，參見內核說明文檔linux-2.6.38.8/Documentation/lockdep-design.txt
[cpp] view plain copy#ifdef CONFIG_LOCKDEP # define MAX_LOCK_DEPTH 48UL u64 curr_chain_key; int lockdep_depth; unsigned int lockdep_recursion; struct held_lock held_locks[MAX_LOCK_DEPTH]; gfp_t lockdep_reclaim_gfp; #endif（30）、JFS文件系統
[cpp] view plain copy/* journalling filesystem info */ void *journal_info;（31）、塊設備鏈表
[cpp] view plain copy/* stacked block device info */ struct bio_list *bio_list;（32）、內存回收
[cpp] view plain copystruct reclaim_state *reclaim_state;（33）、存放塊設備I/O數據流量信息
[cpp] view plain copystruct backing_dev_info *backing_dev_info; （34）、I/O調度器所使用的信息 [cpp] view plain copystruct io_context *io_context;（35）、記錄進程的I/O計數
[cpp] view plain copystruct task_io_accounting ioac; if defined(CONFIG_TASK_XACCT) u64 acct_rss_mem1; /* accumulated rss usage */ u64 acct_vm_mem1; /* accumulated virtual memory usage */ cputime_t acct_timexpd; /* stime + utime since last update */ endif在Ubuntu 11.04上，執行cat獲得進程1的I/O計數如下：
[cpp] view plain copy$ sudo cat /proc/1/io [cpp] view plain copyrchar: 164258906 wchar: 455212837 syscr: 388847 syscw: 92563 read_bytes: 439251968 write_bytes: 14143488 cancelled_write_bytes: 2134016輸出的數據項剛好是task_io_accounting結構體的所有成員。
（36）、CPUSET功能
[cpp] view plain copy#ifdef CONFIG_CPUSETS nodemask_t mems_allowed; /* Protected by alloc_lock */ int mems_allowed_change_disable; int cpuset_mem_spread_rotor; int cpuset_slab_spread_rotor; #endif（37）、Control Groups
[cpp] view plain copy#ifdef CONFIG_CGROUPS /* Control Group info protected by css_set_lock */ struct css_set __rcu *cgroups; /* cg_list protected by css_set_lock and tsk->alloc_lock */ struct list_head cg_list; #endif #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */ struct memcg_batch_info { int do_batch; /* incremented when batch uncharge started */ struct mem_cgroup *memcg; /* target memcg of uncharge */ unsigned long bytes; /* uncharged usage */ unsigned long memsw_bytes; /* uncharged mem+swap usage */ } memcg_batch; #endif（38）、futex同步機制
[cpp] view plain copy#ifdef CONFIG_FUTEX struct robust_list_head __user *robust_list; #ifdef CONFIG_COMPAT struct compat_robust_list_head __user *compat_robust_list; #endif struct list_head pi_state_list; struct futex_pi_state *pi_state_cache; #endif（39）、非一致內存訪問（NUMA Non-Uniform Memory Access）
[cpp] view plain copy#ifdef CONFIG_NUMA struct mempolicy *mempolicy; /* Protected by alloc_lock */ short il_next; #endif（40）、文件系統互斥資源
[cpp] view plain copyatomic_t fs_excl; /* holding fs exclusive resources */（41）、RCU鏈表
[cpp] view plain copystruct rcu_head rcu;（42）、管道
[cpp] view plain copystruct pipe_inode_info *splice_pipe;（43）、延遲計數
[cpp] view plain copy#ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info *delays; #endif（44）、fault injection，參考內核說明文件linux-2.6.38.8/Documentation/fault-injection/fault-injection.txt
[cpp] view plain copy#ifdef CONFIG_FAULT_INJECTION int make_it_fail; #endif（45）、FLoating proportions
[cpp] view plain copystruct prop_local_single dirties;（46）、Infrastructure for displayinglatency
[cpp] view plain copy#ifdef CONFIG_LATENCYTOP int latency_record_count; struct latency_record latency_record[LT_SAVECOUNT]; #endif（47）、time slack values，常用于poll和select函數
[cpp] view plain copyunsigned long timer_slack_ns; unsigned long default_timer_slack_ns;（48）、socket控制消息（control message）
[cpp] view plain copystruct list_head *scm_work_list;（49）、ftrace跟蹤器
[cpp] view plain copy#ifdef CONFIG_FUNCTION_GRAPH_TRACER /* Index of current stored address in ret_stack */ int curr_ret_stack; /* Stack of return addresses for return function tracing */ struct ftrace_ret_stack *ret_stack; /* time stamp for last schedule */ unsigned long long ftrace_timestamp; /* * Number of functions that haven't been traced * because of depth overrun. */ atomic_t trace_overrun; /* Pause for the tracing */ atomic_t tracing_graph_pause; #endif #ifdef CONFIG_TRACING /* state flags for use by tracers */ unsigned long trace; /* bitmask of trace recursion */ unsigned long trace_recursion; #endif /* CONFIG_TRACING */9、進程地址空間
[cpp] view plain copy struct mm_struct *mm, *active_mm; #ifdef CONFIG_COMPAT_BRK unsigned brk_randomized:1; #endif #if defined(SPLIT_RSS_COUNTING) struct task_rss_stat rss_stat; #endifmm指向進程所擁有的內存描述符，而active_mm指向進程運行時所使用的內存描述符。對于普通進程而言，這兩個指針變量的值相同。但是，內核線程不擁有任何內存描述符，所以它們的mm成員總是為NULL。當內核線程得以運行時，它的active_mm成員被初始化為前一個運行進程的 active_mm值。
brk_randomized的用法在http://lkml.indiana.edu/hypermail/linux/kernel/1104.1/00196.html上有介紹，用來確定對隨機堆內存的探測。
rss_stat用來記錄緩沖信息。
10、判斷標志
[cpp] view plain copy int exit_code, exit_signal; int pdeath_signal; /* The signal sent when the parent dies */ /* ??? */ unsigned int personality; unsigned did_exec:1; unsigned in_execve:1; /* Tell the LSMs that the process is doing an * execve */ unsigned in_iowait:1; /* Revert to default priority/policy when forking */ unsigned sched_reset_on_fork:1;exit_code用于設置進程的終止代號，這個值要么是_exit()或exit_group()系統調用參數（正常終止），要么是由內核提供的一個錯誤代號（異常終止）。
exit_signal被置為-1時表示是某個線程組中的一員。只有當線程組的最后一個成員終止時，才會產生一個信號，以通知線程組的領頭進程的父進程。
pdeath_signal用于判斷父進程終止時發送信號。
personality用于處理不同的ABI，它的可能取值如下：
[cpp] view plain copy enum { PER_LINUX = 0x0000, PER_LINUX_32BIT = 0x0000 | ADDR_LIMIT_32BIT, PER_LINUX_FDPIC = 0x0000 | FDPIC_FUNCPTRS, PER_SVR4 = 0x0001 | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, PER_SVR3 = 0x0002 | STICKY_TIMEOUTS | SHORT_INODE, PER_SCOSVR3 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS | SHORT_INODE, PER_OSR5 = 0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS, PER_WYSEV386 = 0x0004 | STICKY_TIMEOUTS | SHORT_INODE, PER_ISCR4 = 0x0005 | STICKY_TIMEOUTS, PER_BSD = 0x0006, PER_SUNOS = 0x0006 | STICKY_TIMEOUTS, PER_XENIX = 0x0007 | STICKY_TIMEOUTS | SHORT_INODE, PER_LINUX32 = 0x0008, PER_LINUX32_3GB = 0x0008 | ADDR_LIMIT_3GB, PER_IRIX32 = 0x0009 | STICKY_TIMEOUTS,/* IRIX5 32-bit */ PER_IRIXN32 = 0x000a | STICKY_TIMEOUTS,/* IRIX6 new 32-bit */ PER_IRIX64 = 0x000b | STICKY_TIMEOUTS,/* IRIX6 64-bit */ PER_RISCOS = 0x000c, PER_SOLARIS = 0x000d | STICKY_TIMEOUTS, PER_UW7 = 0x000e | STICKY_TIMEOUTS | MMAP_PAGE_ZERO, PER_OSF4 = 0x000f, /* OSF/1 v4 */ PER_HPUX = 0x0010, PER_MASK = 0x00ff, };did_exec用于記錄進程代碼是否被execve()函數所執行。
in_execve用于通知LSM是否被do_execve()函數所調用。詳見補丁說明：http://lkml.indiana.edu/hypermail/linux/kernel/0901.1/00014.html。
in_iowait用于判斷是否進行iowait計數。
sched_reset_on_fork用于判斷是否恢復默認的優先級或調度策略。
11、時間
[cpp] view plain copy cputime_t utime, stime, utimescaled, stimescaled; cputime_t gtime; #ifndef CONFIG_VIRT_CPU_ACCOUNTING cputime_t prev_utime, prev_stime; #endif unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; /* monotonic time */ struct timespec real_start_time; /* boot based time */ struct task_cputime cputime_expires; struct list_head cpu_timers[3]; #ifdef CONFIG_DETECT_HUNG_TASK /* hung task detection */ unsigned long last_switch_count; #endifutime/stime用于記錄進程在用戶態/內核態下所經過的節拍數（定時器）。prev_utime/prev_stime是先前的運行時間，請參考補丁說明http://lkml.indiana.edu/hypermail/linux/kernel/1003.3/02431.html。
utimescaled/stimescaled也是用于記錄進程在用戶態/內核態的運行時間，但它們以處理器的頻率為刻度。
gtime是以節拍計數的虛擬機運行時間（guest time）。
nvcsw/nivcsw是自愿（voluntary）/非自愿（involuntary）上下文切換計數。last_switch_count是nvcsw和nivcsw的總和。
start_time和real_start_time都是進程創建時間，real_start_time還包含了進程睡眠時間，常用于/proc/pid/stat，補丁說明請參考http://lkml.indiana.edu/hypermail/linux/kernel/0705.0/2094.html。
cputime_expires用來統計進程或進程組被跟蹤的處理器時間，其中的三個成員對應著cpu_timers[3]的三個鏈表。
12、信號處理
[cpp] view plain copy /* signal handlers */ struct signal_struct *signal; struct sighand_struct *sighand; sigset_t blocked, real_blocked; sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */ struct sigpending pending; unsigned long sas_ss_sp; size_t sas_ss_size; int (*notifier)(void *priv); void *notifier_data; sigset_t *notifier_mask;signal指向進程的信號描述符。
sighand指向進程的信號處理程序描述符。
blocked表示被阻塞信號的掩碼，real_blocked表示臨時掩碼。
pending存放私有掛起信號的數據結構。
sas_ss_sp是信號處理程序備用堆棧的地址，sas_ss_size表示堆棧的大小。
設備驅動程序常用notifier指向的函數來阻塞進程的某些信號（notifier_mask是這些信號的位掩碼），notifier_data指的是notifier所指向的函數可能使用的數據。
13、其他
（1）、用于保護資源分配或釋放的自旋鎖
[cpp] view plain copy /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, * mempolicy */ spinlock_t alloc_lock;（2）、進程描述符使用計數，被置為2時，表示進程描述符正在被使用而且其相應的進程處于活動狀態。
[cpp] view plain copy atomic_t usage;（3）、用于表示獲取大內核鎖的次數，如果進程未獲得過鎖，則置為-1。
[cpp] view plain copy int lock_depth; /* BKL lock depth */（4）、在SMP上幫助實現無加鎖的進程切換（unlocked context switches）
[cpp] view plain copy #ifdef CONFIG_SMP #ifdef __ARCH_WANT_UNLOCKED_CTXSW int oncpu; #endif #endif（5）、preempt_notifier結構體鏈表
[cpp] view plain copy #ifdef CONFIG_PREEMPT_NOTIFIERS /* list of struct preempt_notifier: */ struct hlist_head preempt_notifiers; #endif（6）、FPU使用計數
[cpp] view plain copy unsigned char fpu_counter;（7）、blktrace是一個針對Linux內核中塊設備I/O層的跟蹤工具。
[cpp] view plain copy #ifdef CONFIG_BLK_DEV_IO_TRACE unsigned int btrace_seq; #endif（8）、RCU同步原語
[cpp] view plain copy #ifdef CONFIG_PREEMPT_RCU int rcu_read_lock_nesting; char rcu_read_unlock_special; struct list_head rcu_node_entry; #endif /* #ifdef CONFIG_PREEMPT_RCU */ #ifdef CONFIG_TREE_PREEMPT_RCU struct rcu_node *rcu_blocked_node; #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ #ifdef CONFIG_RCU_BOOST struct rt_mutex *rcu_boost_mutex; #endif /* #ifdef CONFIG_RCU_BOOST */（9）、用于調度器統計進程的運行信息
[cpp] view plain copy #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif（10）、用于構建進程鏈表
[cpp] view plain copy struct list_head tasks;（11）、to limit pushing to one attempt
[cpp] view plain copy #ifdef CONFIG_SMP struct plist_node pushable_tasks; #endif補丁說明請參考：http://lkml.indiana.edu/hypermail/linux/kernel/0808.3/0503.html
（12）、防止內核堆棧溢出
[cpp] view plain copy #ifdef CONFIG_CC_STACKPROTECTOR /* Canary value for the -fstack-protector gcc feature */ unsigned long stack_canary; #endif在GCC編譯內核時，需要加上-fstack-protector選項。
（13）、PID散列表和鏈表
[cpp] view plain copy /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; //線程組中所有進程的鏈表（14）、do_fork函數
[cpp] view plain copy struct completion *vfork_done; /* for vfork() */ int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */在執行do_fork()時，如果給定特別標志，則vfork_done會指向一個特殊地址。
如果copy_process函數的clone_flags參數的值被置為CLONE_CHILD_SETTID或 CLONE_CHILD_CLEARTID，則會把child_tidptr參數的值分別復制到set_child_tid和 clear_child_tid成員。這些標志說明必須改變子進程用戶態地址空間的child_tidptr所指向的變量的值。
（15）、缺頁統計
[cpp] view plain copy /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ unsigned long min_flt, maj_flt;（16）、進程權能
[cpp] view plain copy const struct cred __rcu *real_cred; /* objective and real subjective task * credentials (COW) */ const struct cred __rcu *cred; /* effective (overridable) subjective task * credentials (COW) */ struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */（17）、相應的程序名
[cpp] view plain copy char comm[TASK_COMM_LEN];（18）、文件
[cpp] view plain copy /* file system info */ int link_count, total_link_count; /* filesystem information */ struct fs_struct *fs; /* open file information */ struct files_struct *files;fs用來表示進程與文件系統的聯系，包括當前目錄和根目錄。
files表示進程當前打開的文件。
（19）、進程通信（SYSVIPC）
[cpp] view plain copy #ifdef CONFIG_SYSVIPC /* ipc stuff */ struct sysv_sem sysvsem; #endif（20）、處理器特有數據
[cpp] view plain copy /* CPU-specific state of this task */ struct thread_struct thread;（21）、命名空間
[cpp] view plain copy /* namespaces */ struct nsproxy *nsproxy;（22）、進程審計
[cpp] view plain copy struct audit_context *audit_context; #ifdef CONFIG_AUDITSYSCALL uid_t loginuid; unsigned int sessionid; #endif（23）、secure computing
[cpp] view plain copyseccomp_t seccomp;（24）、用于copy_process函數使用CLONE_PARENT 標記時
[cpp] view plain copy/* Thread group tracking */ u32 parent_exec_id; u32 self_exec_id;（25）、中斷
[cpp] view plain copy#ifdef CONFIG_GENERIC_HARDIRQS /* IRQ handler threads */ struct irqaction *irqaction; #endif #ifdef CONFIG_TRACE_IRQFLAGS unsigned int irq_events; unsigned long hardirq_enable_ip; unsigned long hardirq_disable_ip; unsigned int hardirq_enable_event; unsigned int hardirq_disable_event; int hardirqs_enabled; int hardirq_context; unsigned long softirq_disable_ip; unsigned long softirq_enable_ip; unsigned int softirq_disable_event; unsigned int softirq_enable_event; int softirqs_enabled; int softirq_context; #endif（26）、task_rq_lock函數所使用的鎖
[cpp] view plain copy/* Protection of the PI data structures: */ raw_spinlock_t pi_lock;（27）、基于PI協議的等待互斥鎖，其中PI指的是priority inheritance（優先級繼承）
[cpp] view plain copy#ifdef CONFIG_RT_MUTEXES /* PI waiters blocked on a rt_mutex held by this task */ struct plist_head pi_waiters; /* Deadlock detection and priority inheritance handling */ struct rt_mutex_waiter *pi_blocked_on; #endif（28）、死鎖檢測
[cpp] view plain copy#ifdef CONFIG_DEBUG_MUTEXES /* mutex deadlock detection */ struct mutex_waiter *blocked_on; #endif（29）、lockdep，參見內核說明文檔linux-2.6.38.8/Documentation/lockdep-design.txt
[cpp] view plain copy#ifdef CONFIG_LOCKDEP # define MAX_LOCK_DEPTH 48UL u64 curr_chain_key; int lockdep_depth; unsigned int lockdep_recursion; struct held_lock held_locks[MAX_LOCK_DEPTH]; gfp_t lockdep_reclaim_gfp; #endif（30）、JFS文件系統
[cpp] view plain copy/* journalling filesystem info */ void *journal_info;（31）、塊設備鏈表
[cpp] view plain copy/* stacked block device info */ struct bio_list *bio_list;（32）、內存回收
[cpp] view plain copystruct reclaim_state *reclaim_state;（33）、存放塊設備I/O數據流量信息
[cpp] view plain copystruct backing_dev_info *backing_dev_info;（34）、I/O調度器所使用的信息
[cpp] view plain copystruct io_context *io_context;（35）、記錄進程的I/O計數
[cpp] view plain copystruct task_io_accounting ioac; if defined(CONFIG_TASK_XACCT) u64 acct_rss_mem1; /* accumulated rss usage */ u64 acct_vm_mem1; /* accumulated virtual memory usage */ cputime_t acct_timexpd; /* stime + utime since last update */ endif在Ubuntu 11.04上，執行cat獲得進程1的I/O計數如下：
[cpp] view plain copy$ sudo cat /proc/1/io [cpp] view plain copyrchar: 164258906 wchar: 455212837 syscr: 388847 syscw: 92563 read_bytes: 439251968 write_bytes: 14143488 cancelled_write_bytes: 2134016輸出的數據項剛好是task_io_accounting結構體的所有成員。
（36）、CPUSET功能
[cpp] view plain copy#ifdef CONFIG_CPUSETS nodemask_t mems_allowed; /* Protected by alloc_lock */ int mems_allowed_change_disable; int cpuset_mem_spread_rotor; int cpuset_slab_spread_rotor; #endif（37）、Control Groups
[cpp] view plain copy#ifdef CONFIG_CGROUPS /* Control Group info protected by css_set_lock */ struct css_set __rcu *cgroups; /* cg_list protected by css_set_lock and tsk->alloc_lock */ struct list_head cg_list; #endif #ifdef CONFIG_CGROUP_MEM_RES_CTLR /* memcg uses this to do batch job */ struct memcg_batch_info { int do_batch; /* incremented when batch uncharge started */ struct mem_cgroup *memcg; /* target memcg of uncharge */ unsigned long bytes; /* uncharged usage */ unsigned long memsw_bytes; /* uncharged mem+swap usage */ } memcg_batch; #endif（38）、futex同步機制
[cpp] view plain copy#ifdef CONFIG_FUTEX struct robust_list_head __user *robust_list; #ifdef CONFIG_COMPAT struct compat_robust_list_head __user *compat_robust_list; #endif struct list_head pi_state_list; struct futex_pi_state *pi_state_cache; #endif（39）、非一致內存訪問（NUMA Non-Uniform Memory Access）
[cpp] view plain copy#ifdef CONFIG_NUMA struct mempolicy *mempolicy; /* Protected by alloc_lock */ short il_next; #endif（40）、文件系統互斥資源
[cpp] view plain copyatomic_t fs_excl; /* holding fs exclusive resources */（41）、RCU鏈表
[cpp] view plain copystruct rcu_head rcu;（42）、管道
[cpp] view plain copystruct pipe_inode_info *splice_pipe;（43）、延遲計數
[cpp] view plain copy#ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info *delays; #endif（44）、fault injection，參考內核說明文件linux-2.6.38.8/Documentation/fault-injection/fault-injection.txt
[cpp] view plain copy#ifdef CONFIG_FAULT_INJECTION int make_it_fail; #endif（45）、FLoating proportions
[cpp] view plain copystruct prop_local_single dirties;（46）、Infrastructure for displayinglatency
[cpp] view plain copy#ifdef CONFIG_LATENCYTOP int latency_record_count; struct latency_record latency_record[LT_SAVECOUNT]; #endif（47）、time slack values，常用于poll和select函數
[cpp] view plain copyunsigned long timer_slack_ns; unsigned long default_timer_slack_ns;（48）、socket控制消息（control message）
[cpp] view plain copystruct list_head *scm_work_list;（49）、ftrace跟蹤器
[cpp] view plain copy#ifdef CONFIG_FUNCTION_GRAPH_TRACER /* Index of current stored address in ret_stack */ int curr_ret_stack; /* Stack of return addresses for return function tracing */ struct ftrace_ret_stack *ret_stack; /* time stamp for last schedule */ unsigned long long ftrace_timestamp; /* * Number of functions that haven't been traced * because of depth overrun. */ atomic_t trace_overrun; /* Pause for the tracing */ atomic_t tracing_graph_pause; #endif #ifdef CONFIG_TRACING /* state flags for use by tracers */ unsigned long trace; /* bitmask of trace recursion */ unsigned long trace_recursion; #endif /* CONFIG_TRACING */新聞熱點
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