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内核源码：Linux-2.6.38.8.tar.bz2
目标平台：ARM体系结构
进程是处于执行期的程序以及它所管理的资源（如打开的文件、挂起的信号、进程状态、地址空间等等）的总称。注意，程序并不是进程，实际上两个或多个进程不仅有可能执行同一程序，而且还有可能共享地址空间等资源。
Linux内核通过一个被称为进程描述符的task_struct结构体来管理进程，这个结构体包含了一个进程所需的所有信息。它定义在linux-2.6.38.8/include/linux/sched.h文件中。
本文将尽力就task_struct结构体所有成员的用法进行简要说明。
1、进程状态
[cpp] view plain copy print? volatile long state; int exit_state; volatile long state; int exit_state;state成员的可能取值如下：
[cpp] view plain copy print? #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 #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系统中的每个进程都必然处于以上所列进程状态中的一种。
TASK_RUNNING表示进程要么正在执行，要么正要准备执行。
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。
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。
__TASK_STOPPED表示进程被停止执行。
__TASK_TRACED表示进程被debugger等进程监视。
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。
EXIT_DEAD表示进程的最终状态。
EXIT_ZOMBIE和EXIT_DEAD也可以存放在exit_state成员中。进程状态的切换过程和原因大致如下图（图片来自《Linux Kernel Development》）：
2、进程标识符（PID）
[cpp] view plain copy print? pid_t pid; pid_t tgid; pid_t pid; pid_t tgid;在CONFIG_BASE_SMALL配置为0的情况下，PID的取值范围是0到32767，即系统中的进程数最大为32768个。
[cpp] view plain copy print? /* linux-2.6.38.8/include/linux/threads.h */ #define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000) /* linux-2.6.38.8/include/linux/threads.h */ #define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)在Linux系统中，一个线程组中的所有线程使用和该线程组的领头线程（该组中的第一个轻量级进程）相同的PID，并被存放在tgid成员中。只有线程组的领头线程的pid成员才会被设置为与tgid相同的值。注意，getpid()系统调用返回的是当前进程的tgid值而不是pid值。
3、进程内核栈
[cpp] view plain copy print? void *stack; void *stack;进程通过alloc_thread_info函数分配它的内核栈，通过free_thread_info函数释放所分配的内核栈。
[cpp] view plain copy print? /* 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); } /* 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）。
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。
[cpp] view plain copy print? union thread_union { struct thread_info thread_info; unsigned long stack[THREAD_SIZE/sizeof(long)]; }; union thread_union { struct thread_info thread_info; unsigned long stack[THREAD_SIZE/sizeof(long)]; };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。
[cpp] view plain copy print? /* 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)); } /* 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)); }
进程内核栈与进程描述符的关系如下图：
4、标记
[cpp] view plain copy print? unsigned int flags; /* per process flags, defined below */ unsigned int flags; /* per process flags, defined below */flags成员的可能取值如下：
[cpp] view plain copy print? #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_SKIP 0x40000000 /* Freezer should not count it as freezable */ #define PF_FREEZER_NOSIG 0x80000000 /* Freezer won't send signals to it */ #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_SKIP 0x40000000 /* Freezer should not count it as freezable */ #define PF_FREEZER_NOSIG 0x80000000 /* Freezer won't send signals to it */5、表示进程亲属关系的成员
[cpp] view plain copy print? 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 */ 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系统中，所有进程之间都有着直接或间接地联系，每个进程都有其父进程，也可能有零个或多个子进程。拥有同一父进程的所有进程具有兄弟关系。
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。
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。
children表示链表的头部，链表中的所有元素都是它的子进程。
sibling用于把当前进程插入到兄弟链表中。
group_leader指向其所在进程组的领头进程。
6、ptrace系统调用
[cpp] view plain copy print? 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 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成员ptrace被设置为0时表示不需要被跟踪，它的可能取值如下：
[cpp] view plain copy print? /* 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 0x00000200 /* 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 print? #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; #endif #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是一款随 Linux 内核代码一同发布和维护的性能诊断工具。这些成员用于帮助PerformanceEvent分析进程的性能问题。
关于Performance Event工具的介绍可参考文章http://www.ibm.com/developerworks/cn/linux/l-cn-perf1/index.html?ca=drs-#major1和http://www.ibm.com/developerworks/cn/linux/l-cn-perf2/index.html?ca=drs-#major1。
8、进程调度
[cpp] view plain copy print? 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; 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;实时优先级范围是0到MAX_RT_PRIO-1（即99），而普通进程的静态优先级范围是从MAX_RT_PRIO到MAX_PRIO-1（即100到139）。值越大静态优先级越低。
[cpp] view plain copy print? /* 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) /* 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用于保存静态优先级，可以通过nice系统调用来进行修改。
rt_priority用于保存实时优先级。
normal_prio的值取决于静态优先级和调度策略。
prio用于保存动态优先级。
policy表示进程的调度策略，目前主要有以下五种：
[cpp] view plain copy print? #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 5 #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用于普通进程，通过CFS调度器实现。SCHED_BATCH用于非交互的处理器消耗型进程。SCHED_IDLE是在系统负载很低时使用。
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。
sched_class结构体表示调度类，目前内核中有实现以下四种：
[cpp] view plain copy print? /* 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; /* 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。
cpus_allowed用于控制进程可以在哪里处理器上运行。
9、进程地址空间
[cpp] view plain copy print? 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; #endif 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。
brk_randomized的用法在http://lkml.indiana.edu/hypermail/Linux/kernel/1104.1/00196.html上有介绍，用来确定对随机堆内存的探测。
rss_stat用来记录缓冲信息。
10、判断标志
[cpp] view plain copy print? 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; 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;</pre>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）。
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。
pdeath_signal用于判断父进程终止时发送信号。
personality用于处理不同的ABI，它的可能取值如下：
[cpp] view plain copy print? 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, }; 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用于记录进程代码是否被execve()函数所执行。
in_execve用于通知LSM是否被do_execve()函数所调用。详见补丁说明：http://lkml.indiana.edu/hypermail/linux/kernel/0901.1/00014.html。
in_iowait用于判断是否进行iowait计数。
sched_reset_on_fork用于判断是否恢复默认的优先级或调度策略。
11、时间
[cpp] view plain copy print? 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; #endif 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用于记录进程在用户态/内核态下所经过的节拍数（定时器）。prev_utime/prev_stime是先前的运行时间，请参考补丁说明http://lkml.indiana.edu/hypermail/linux/kernel/1003.3/02431.html。
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。
gtime是以节拍计数的虚拟机运行时间（guest time）。
nvcsw/nivcsw是自愿（voluntary）/非自愿（involuntary）上下文切换计数。last_switch_count是nvcsw和nivcsw的总和。
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，补丁说明请参考http://lkml.indiana.edu/hypermail/linux/kernel/0705.0/2094.html。
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、信号处理
[cpp] view plain copy print? /* 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 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;</pre>signal指向进程的信号描述符。
sighand指向进程的信号处理程序描述符。
blocked表示被阻塞信号的掩码，real_blocked表示临时掩码。
pending存放私有挂起信号的数据结构。
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。
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。
13、其他
（1）、用于保护资源分配或释放的自旋锁
[cpp] view plain copy print? /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, * mempolicy */ spinlock_t alloc_lock; /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, * mempolicy */ spinlock_t alloc_lock;（2）、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。
[cpp] view plain copy print? atomic_t usage; atomic_t usage;（3）、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。
[cpp] view plain copy print? int lock_depth; /* BKL lock depth */ int lock_depth; /* BKL lock depth */（4）、在SMP上帮助实现无加锁的进程切换（unlocked context switches）
[cpp] view plain copy print? #ifdef CONFIG_SMP #ifdef __ARCH_WANT_UNLOCKED_CTXSW int oncpu; #endif #endif #ifdef CONFIG_SMP #ifdef __ARCH_WANT_UNLOCKED_CTXSW int oncpu; #endif #endif（5）、preempt_notifier结构体链表
[cpp] view plain copy print? #ifdef CONFIG_PREEMPT_NOTIFIERS /* list of struct preempt_notifier: */ struct hlist_head preempt_notifiers; #endif #ifdef CONFIG_PREEMPT_NOTIFIERS /* list of struct preempt_notifier: */ struct hlist_head preempt_notifiers; #endif（6）、FPU使用计数
[cpp] view plain copy print? unsigned char fpu_counter; unsigned char fpu_counter;（7）、blktrace是一个针对Linux内核中块设备I/O层的跟踪工具。
[cpp] view plain copy print? #ifdef CONFIG_BLK_DEV_IO_TRACE unsigned int btrace_seq; #endif #ifdef CONFIG_BLK_DEV_IO_TRACE unsigned int btrace_seq; #endif（8）、RCU同步原语
[cpp] view plain copy print? #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 */ #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）、用于调度器统计进程的运行信息
[cpp] view plain copy print? #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif（10）、用于构建进程链表
[cpp] view plain copy print? struct list_head tasks; struct list_head tasks;（11）、to limit pushing to one attempt
[cpp] view plain copy print? #ifdef CONFIG_SMP struct plist_node pushable_tasks; #endif #ifdef CONFIG_SMP struct plist_node pushable_tasks; #endif补丁说明请参考：http://lkml.indiana.edu/hypermail/linux/kernel/0808.3/0503.html
（12）、防止内核堆栈溢出
[cpp] view plain copy print? #ifdef CONFIG_CC_STACKPROTECTOR /* Canary value for the -fstack-protector gcc feature */ unsigned long stack_canary; #endif #ifdef CONFIG_CC_STACKPROTECTOR /* Canary value for the -fstack-protector gcc feature */ unsigned long stack_canary; #endif在GCC编译内核时，需要加上-fstack-protector选项。
（13）、PID散列表和链表
[cpp] view plain copy print? /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; //线程组中所有进程的链表 /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; //线程组中所有进程的链表（14）、do_fork函数
[cpp] view plain copy print? struct completion *vfork_done; /* for vfork() */ int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */ struct completion *vfork_done; /* for vfork() */ int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */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。
（15）、缺页统计
[cpp] view plain copy print? /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ unsigned long min_flt, maj_flt; /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ unsigned long min_flt, maj_flt;（16）、进程权能
[cpp] view plain copy print? 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 */ 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）、相应的程序名
[cpp] view plain copy print? char comm[TASK_COMM_LEN]; char comm[TASK_COMM_LEN];（18）、文件
[cpp] view plain copy print? /* file system info */ int link_count, total_link_count; /* filesystem information */ struct fs_struct *fs; /* open file information */ struct files_struct *files; /* file system info */ int link_count, total_link_count; /* filesystem information */ struct fs_struct *fs; /* open file information */ struct files_struct *files;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。
files表示进程当前打开的文件。
（19）、进程通信（SYSVIPC）
[cpp] view plain copy print? #ifdef CONFIG_SYSVIPC /* ipc stuff */ struct sysv_sem sysvsem; #endif #ifdef CONFIG_SYSVIPC /* ipc stuff */ struct sysv_sem sysvsem; #endif（20）、处理器特有数据
[cpp] view plain copy print? /* CPU-specific state of this task */ struct thread_struct thread; /* CPU-specific state of this task */ struct thread_struct thread;（21）、命名空间
[cpp] view plain copy print? /* namespaces */ struct nsproxy *nsproxy; /* namespaces */ struct nsproxy *nsproxy;（22）、进程审计
[cpp] view plain copy print? struct audit_context *audit_context; #ifdef CONFIG_AUDITSYSCALL uid_t loginuid; unsigned int sessionid; #endif struct audit_context *audit_context; #ifdef CONFIG_AUDITSYSCALL uid_t loginuid; unsigned int sessionid; #endif（23）、secure computing
[cpp] view plain copy print? seccomp_t seccomp; seccomp_t seccomp;（24）、用于copy_process函数使用CLONE_PARENT 标记时
[cpp] view plain copy print? /* Thread group tracking */ u32 parent_exec_id; u32 self_exec_id; /* Thread group tracking */ u32 parent_exec_id; u32 self_exec_id;（25）、中断
[cpp] view plain copy print? #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 #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函数所使用的锁
[cpp] view plain copy print? /* Protection of the PI data structures: */ raw_spinlock_t pi_lock; /* Protection of the PI data structures: */ raw_spinlock_t pi_lock;（27）、基于PI协议的等待互斥锁，其中PI指的是priority inheritance（优先级继承）
[cpp] view plain copy print? #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 #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）、死锁检测
[cpp] view plain copy print? #ifdef CONFIG_DEBUG_MUTEXES /* mutex deadlock detection */ struct mutex_waiter *blocked_on; #endif #ifdef CONFIG_DEBUG_MUTEXES /* mutex deadlock detection */ struct mutex_waiter *blocked_on; #endif（29）、lockdep，参见内核说明文档linux-2.6.38.8/Documentation/lockdep-design.txt
[cpp] view plain copy print? #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 #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文件系统
[cpp] view plain copy print? /* journalling filesystem info */ void *journal_info; /* journalling filesystem info */ void *journal_info;（31）、块设备链表
[cpp] view plain copy print? /* stacked block device info */ struct bio_list *bio_list; /* stacked block device info */ struct bio_list *bio_list;（32）、内存回收
[cpp] view plain copy print? struct reclaim_state *reclaim_state; struct reclaim_state *reclaim_state;（33）、存放块设备I/O数据流量信息
[cpp] view plain copy print? struct backing_dev_info *backing_dev_info; struct backing_dev_info *backing_dev_info;（34）、I/O调度器所使用的信息
[cpp] view plain copy print? struct io_context *io_context; struct io_context *io_context;（35）、记录进程的I/O计数
[cpp] view plain copy print? struct 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 struct 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，执行cat获得进程1的I/O计数如下：
[cpp] view plain copy print? $ sudo cat /proc/1/io $ sudo cat /proc/1/io [cpp] view plain copy print? rchar: 164258906 wchar: 455212837 syscr: 388847 syscw: 92563 read_bytes: 439251968 write_bytes: 14143488 cancelled_write_bytes: 2134016 rchar: 164258906 wchar: 455212837 syscr: 388847 syscw: 92563 read_bytes: 439251968 write_bytes: 14143488 cancelled_write_bytes: 2134016输出的数据项刚好是task_io_accounting结构体的所有成员。
（36）、CPUSET功能
[cpp] view plain copy print? #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 #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 print? #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 #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同步机制
[cpp] view plain copy print? #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 #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）、非一致内存访问（NUMA Non-Uniform Memory Access）
[cpp] view plain copy print? #ifdef CONFIG_NUMA struct mempolicy *mempolicy; /* Protected by alloc_lock */ short il_next; #endif #ifdef CONFIG_NUMA struct mempolicy *mempolicy; /* Protected by alloc_lock */ short il_next; #endif（40）、文件系统互斥资源
[cpp] view plain copy print? atomic_t fs_excl; /* holding fs exclusive resources */ atomic_t fs_excl; /* holding fs exclusive resources */（41）、RCU链表
[cpp] view plain copy print? struct rcu_head rcu; struct rcu_head rcu;（42）、管道
[cpp] view plain copy print? struct pipe_inode_info *splice_pipe; struct pipe_inode_info *splice_pipe;（43）、延迟计数
[cpp] view plain copy print? #ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info *delays; #endif #ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info *delays; #endif（44）、fault injection，参考内核说明文件linux-2.6.38.8/Documentation/fault-injection/fault-injection.txt
[cpp] view plain copy print? #ifdef CONFIG_FAULT_INJECTION int make_it_fail; #endif #ifdef CONFIG_FAULT_INJECTION int make_it_fail; #endif（45）、FLoating proportions
[cpp] view plain copy print? struct prop_local_single dirties; struct prop_local_single dirties;（46）、Infrastructure for displayinglatency
[cpp] view plain copy print? #ifdef CONFIG_LATENCYTOP int latency_record_count; struct latency_record latency_record[LT_SAVECOUNT]; #endif #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函数
[cpp] view plain copy print? unsigned long timer_slack_ns; unsigned long default_timer_slack_ns; unsigned long timer_slack_ns; unsigned long default_timer_slack_ns;（48）、socket控制消息（control message）
[cpp] view plain copy print? struct list_head *scm_work_list; struct list_head *scm_work_list;（49）、ftrace跟踪器
[cpp] view plain copy print? #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 */好文要顶 关注我 收藏该文 zxiaocheng 关注 - 3 粉丝 - 6 +加关注 0 0 « 上一篇： Linux内核同步原语之原子操作 » 下一篇： usb_submit_urb </div> <div class="postDesc">posted @ <span id="post-date">2017-03-31 09:48</span> <a href="https://www.cnblogs.com/zxc2man/">zxiaocheng</a> 阅读(<span id="post_view_count">5939</span>) 评论(<span id="post_comment_count">0</span>) <a href="https://i.cnblogs.com/EditPosts.aspx?postid=6649771" rel="nofollow">编辑</a> <a href="#" onclick="AddToWz(6649771);return false;">收藏</a></div> </div> <script type="text/javascript">var allowComments=true,cb_blogId=168605,cb_entryId=6649771,cb_blogApp=currentBlogApp,cb_blogUserGuid='48b03639-064c-e311-8d02-90b11c0b17d6',cb_entryCreatedDate='2017/3/31 9:48:00';loadViewCount(cb_entryId);var cb_postType=1;var isMarkdown=false;</script> </div><!--end: forFlow --> </div>
