task_struct 结构如何查看及分析

    cd /find -name sched.hvim usr/src/kernels/3.10.0862.6.3.el7.x86_64/include/linux/sched.h

https://www.cnblogs.com/zxc2man/p/6649771.html

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 0x00000200
7、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;
#endif
Performance 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 5
SCHED_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;
#endif
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。

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;
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;
#endif
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）。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;
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 */

本文来自互联网用户投稿，该文观点仅代表作者本人，不代表本站立场。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如若转载，请注明出处：http://www.mzph.cn/news/382511.shtml

如若内容造成侵权/违法违规/事实不符，请联系多彩编程网进行投诉反馈email:809451989@qq.com，一经查实，立即删除！

相关文章

linux 与信号集操作相关的函数

linux 与信号集操作相关的函数

与信号集操作相关的函数 #include <signal.h> 清空信号集 全都为0 int sigemptyset(sigset_t *set);填充信号集 全都为1 int sigfillset(sigset_t *set);添加某个信号到信号集 int sigaddset(sigset_t *set, int signum);从集合中删除某个信号 int sigdelset(sigset_t *s…
阅读更多...
软件工程学习笔记《三》代码优化和性能测试

软件工程学习笔记《三》代码优化和性能测试

文章目录软件工程学习笔记目录如何在开源社区提问&#xff1f;代码审查代码优化运行结果参数解释代码优化原则对常见的数据结构排序算法进行测试关于冒泡排序优化的探讨结果软件工程学习笔记目录 [https://blog.csdn.net/csdn_kou/article/details/83754356] 如何在开源社区提…
阅读更多...
linux信号捕捉

linux信号捕捉

信号捕捉&#xff0c;防止进程意外死亡 signal函数 man signal #include <signal.h> typedef void (*sighandler_t)(int); sighandler_t signal(int signum, sighandler_t handler);参数介绍&#xff1b; signum 要捕捉的信号 handler 要执行的捕捉函数指针&#xff0c…
阅读更多...
软件工程学习笔记《目录》

软件工程学习笔记《目录》

软件工程学习笔记《目录》 软件工程学习笔记《一》什么是软件工程 软件工程学习笔记《二》代码规范 软件工程学习笔记《三》代码优化和性能测试 软件工程学习笔记《四》需求分析
阅读更多...
linux进程利用SIGCHLD信号，来实现父进程回收子进程

linux进程利用SIGCHLD信号，来实现父进程回收子进程

子进程执行完毕后&#xff0c;会向父进程发出 SIGCHLD信号 &#xff0c; 这段代码实现的就是i&#xff0c;父进程接受到子进程 发出的SIGCHLD信号&#xff0c;实现对子进程进行回收&#xff0c;从而避免僵尸进程 #include <stdio.h> #include <unistd.h> #include…
阅读更多...
WWW软件全球使用排名

WWW软件全球使用排名

https://w3techs.com/technologies/overview/web_server/all Apache份额一直下降呀&#xff01;
阅读更多...
软件工程学习笔记《四》需求分析

软件工程学习笔记《四》需求分析

文章目录软件工程学习笔记《目录》需求工程师当代的需求工程师需要具备的能力当代的需求工程师需要努力的方向当代的需求工程师需要注意的错误需求的定义需求目标需求分析的实质需求分析的关键应该涵盖的内容&#xff1f;需求规约&#xff08;作为较客观的参照&#xff09;单个…
阅读更多...
linux守护进程

linux守护进程

先了解 linux系统中 会话的概念 会话是进程组的更高一级&#xff0c;多个进程组对应一个会话。 会话是一个或多个进程组的集合 创建一个会话需要注意以下5点事项&#xff1a; a. 调用进程不能是进程组组长&#xff0c; 该进程变成新会话首进程&#xff08;session header&#…
阅读更多...
python3爬虫学习笔记

python3爬虫学习笔记

文章目录python3的文本处理jieba库的使用统计hamlet.txt文本中高频词的个数统计三国演义任务高频次数爬虫爬取百度首页爬取京东某手机页面BeautifulSoup使用request进行爬取&#xff0c;在使用 BeautifulSoup进行处理&#xff01;拥有一个更好的排版BeautifulSoup爬取百度首页原…
阅读更多...
linux 线程学习初步01

linux 线程学习初步01

线程的概念 进程与线程内核实现 通过函数clone实现的 ps -Lf pidLinux内核线程实现原理 同一个进程下的线程&#xff0c;共享该进程的内存区&#xff0c; 但是只有stack区域不共享。 线程共享资源 a.文件描述符表 b.每种信号的处理方式 c.当前工作目录 d.用户id和组id 线程…
阅读更多...
python3字符串处理，高效切片

python3字符串处理，高效切片

高级技巧&#xff1a;切片&#xff0c;迭代&#xff0c;列表&#xff0c;生成器 切片 L [Hello, World, !]print("-------1.一个一个取-------") print(L[0]) print(L[1]) print(L[2])print("-------2.开辟一个新列表把内容存进去-------") r [] for i…
阅读更多...
linux线程学习初步02

linux线程学习初步02

杀死线程的函数 int pthread_cancel(pthread_t thread); 参数介绍&#xff1a;需要输入的tid 返回值&#xff1a;识别返回 errno成功返回 0 被杀死的线程&#xff0c;退出状态值为一个 #define PTHREAD_CANCELED((void *)-1)代码案例&#xff1a; #include <stdio.h> #…
阅读更多...
python的文件基本操作和文件指针

python的文件基本操作和文件指针

读写模式的基本操作 https://www.cnblogs.com/c-x-m/articles/7756498.html r,w,a r只读模式【默认模式&#xff0c;文件必须存在&#xff0c;不存在则抛出异常】w只写模式【不可读&#xff1b;不存在则创建&#xff1b;存在则清空内容】a之追加写模式【不可读&#xff1b;不…
阅读更多...
python3 将unicode转中文

python3 将unicode转中文

decrypted_str.encode(utf-8).decode(unicode_escape)
阅读更多...
HTTP菜鸟教程速查手册

HTTP菜鸟教程速查手册

HTTP协议&#xff08;HyperText Transfer Protocol&#xff0c;超文本传输协议&#xff09;是因特网上应用最为广泛的一种网络传输协议&#xff0c;所有的WWW文件都必须遵守这个标准。 HTTP是一个基于TCP/IP通信协议来传递数据&#xff08;HTML 文件, 图片文件, 查询结果等&am…
阅读更多...
mysql学习笔记01-创建数据库

mysql学习笔记01-创建数据库

创建数据库&#xff1a; 校验规则&#xff1a;是指表的排序规则和查询时候的规则 utf8_general_ci 支持中文&#xff0c; 且不区分大小写 utf8_bin 支持中文&#xff0c; 区分大小写 比如&#xff1a; create database db3 character set utf8 collate utf8_general_ci; &…
阅读更多...
python的Web编程

python的Web编程

首先看一下效果 完整代码 import socket from multiprocessing import ProcessHTML_ROOT_DIR ""def handle_client(client_socket):request_data client_socket.recv(1024)print("request data:", request_data)response_start_line "HTTP/1.0 20…
阅读更多...
mysql 学习笔记 02创建表

mysql 学习笔记 02创建表

表结构的创建 比如&#xff1a; create table userinfo (id int unsigned comment id号name varchar(60) comment 用户名password char(32),birthday date ) character set utf8 engine MyISAM;comment 表示注释的意思 不同的存储引擎&#xff0c;创建的表的文件不一样
阅读更多...
VMware的屏幕太小

VMware的屏幕太小

好了
阅读更多...
mysql 学习笔记03 常用数据类型

mysql 学习笔记03 常用数据类型

数值类型&#xff1a; a. 整数类型&#xff1a; 注意事项&#xff1a; 举例&#xff1a;某个整型字段 &#xff0c;不为空&#xff0c;且有默认值 create table test (age int unisigned not null default 1);zerofill的使用 b. bit类型的使用 c.小数类型 小数类型占用…
阅读更多...
最新文章

Copyright @ 2022~2023