1、用戶態(tài)和內(nèi)核態(tài),當一個進程在執(zhí)行用戶自己的代碼時處于用戶運行態(tài)(用戶態(tài));當一個進程因為系統(tǒng)調(diào)用陷入內(nèi)核代碼中執(zhí)行時處于內(nèi)核運行態(tài)(內(nèi)核態(tài))。
讓客戶滿意是我們工作的目標,不斷超越客戶的期望值來自于我們對這個行業(yè)的熱愛。我們立志把好的技術(shù)通過有效、簡單的方式提供給客戶,將通過不懈努力成為客戶在信息化領域值得信任、有價值的長期合作伙伴,公司提供的服務項目有:域名申請、網(wǎng)頁空間、營銷軟件、網(wǎng)站建設、烏拉特前網(wǎng)站維護、網(wǎng)站推廣。
2、進程之間的通信(Inter Processs Communication- IPC)實現(xiàn)機制有:管道、消息隊列、信號值、信號、共享內(nèi)存、共享映射文件、套接字等。
3、及時通信:信號(類似中斷);非及時通信:共享內(nèi)存、郵箱、管道、套接字、
4、常見的信號:終止信號、定時器信號、用戶自定義信號等
5、信號: 用戶、系統(tǒng)或者進程發(fā)送給 目標進程的 信息,以通知目標進程某個 狀態(tài)的改變或 系統(tǒng)異常。
6、
PCB(progress control block-進程控制塊),系統(tǒng)通過PCB,描述進程和控制進程。在Linux系統(tǒng)下,PCB是
task_struct結(jié)構(gòu)體(進程描述符)
。
?1、
進程狀態(tài):記錄進程是處于運行狀態(tài)還是等待狀態(tài)
?2、
調(diào)度信息:進程由哪個函數(shù)調(diào)度,具體怎樣調(diào)度等
?3、進程之間的
通訊狀況
?4、進程之間的
親屬關(guān)系:在父進程和子進程之間有task_struct類型的指針,將父進程和子進程聯(lián)系起來
?5、
時間數(shù)據(jù)信息:每個進程執(zhí)行所占用CPU的時間
?6、
進程的標志
?7、
進程的標識符:該進程唯一的標識符用來區(qū)別其他進程
?8、
信號處理信息
?9、
文件信息:可以進行讀寫操作的一些文件的信息
?10、
頁面管理信息
?11、
優(yōu)先級:相對于其他進程的優(yōu)先級
?12、
ptrace系統(tǒng)調(diào)用
?13、
虛擬內(nèi)存處理
struct task_struct { volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */ void *stack; atomic_t usage; unsigned int flags; /* per process flags, defined below */ unsigned int ptrace; int lock_depth; /* BKL lock depth */ #ifdef CONFIG_SMP #ifdef __ARCH_WANT_UNLOCKED_CTXSW int oncpu; #endif #endif 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; #ifdef CONFIG_PREEMPT_NOTIFIERS /* list of struct preempt_notifier: */ struct hlist_head preempt_notifiers; #endif /* * fpu_counter contains the number of consecutive context switches * that the FPU is used. If this is over a threshold, the lazy fpu * saving becomes unlazy to save the trap. This is an unsigned char * so that after 256 times the counter wraps and the behavior turns * lazy again; this to deal with bursty apps that only use FPU for * a short time */ unsigned char fpu_counter; #ifdef CONFIG_BLK_DEV_IO_TRACE unsigned int btrace_seq; #endif unsigned int policy; cpumask_t cpus_allowed; #ifdef CONFIG_TREE_PREEMPT_RCU int rcu_read_lock_nesting; char rcu_read_unlock_special; struct rcu_node *rcu_blocked_node; struct list_head rcu_node_entry; #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) struct sched_info sched_info; #endif struct list_head tasks; struct plist_node pushable_tasks; struct mm_struct *mm, *active_mm; /* task state */ int exit_state; 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; pid_t pid; pid_t tgid; #ifdef CONFIG_CC_STACKPROTECTOR /* Canary value for the -fstack-protector gcc feature */ unsigned long stack_canary; #endif /* * pointers to (original) parent process, youngest child, younger sibling, * older sibling, respectively. (p->father can be replaced with * p->real_parent->pid) */ struct task_struct *real_parent; /* real parent process */ struct task_struct *parent; /* recipient of SIGCHLD, wait4() reports */ /* * children/sibling forms the list of my natural children */ 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 */ /* * ptraced is the list of tasks this task is using ptrace on. * This includes both natural children and PTRACE_ATTACH targets. * p->ptrace_entry is p‘s link on the p->parent->ptraced list. */ struct list_head ptraced; struct list_head ptrace_entry; /* * This is the tracer handle for the ptrace BTS extension. * This field actually belongs to the ptracer task. */ struct bts_context *bts; /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; struct completion *vfork_done; /* for vfork() */ int __user *set_child_tid; /* CLONE_CHILD_SETTID */ int __user *clear_child_tid; /* CLONE_CHILD_CLEARTID */ cputime_t utime, stime, utimescaled, stimescaled; cputime_t gtime; cputime_t prev_utime, prev_stime; unsigned long nvcsw, nivcsw; /* context switch counts */ struct timespec start_time; /* monotonic time */ struct timespec real_start_time; /* boot based time */ /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ unsigned long min_flt, maj_flt; struct task_cputime cputime_expires; struct list_head cpu_timers[3]; /* process credentials */ const struct cred *real_cred; /* objective and real subjective task * credentials (COW) */ const struct cred *cred; /* effective (overridable) subjective task * credentials (COW) */ struct mutex cred_guard_mutex; /* guard against foreign influences on * credential calculations * (notably. ptrace) */ struct cred *replacement_session_keyring; /* for KEYCTL_SESSION_TO_PARENT */ char comm[TASK_COMM_LEN]; /* executable name excluding path - access with [gs]et_task_comm (which lock it with task_lock()) - initialized normally by flush_old_exec */ /* file system info */ int link_count, total_link_count; #ifdef CONFIG_SYSVIPC /* ipc stuff */ struct sysv_sem sysvsem; #endif #ifdef CONFIG_DETECT_HUNG_TASK /* hung task detection */ unsigned long last_switch_count; #endif /* CPU-specific state of this task */ struct thread_struct thread; /* filesystem information */ struct fs_struct *fs; /* open file information */ struct files_struct *files; /* namespaces */ struct nsproxy *nsproxy; /* 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; struct audit_context *audit_context; #ifdef CONFIG_AUDITSYSCALL uid_t loginuid; unsigned int sessionid; #endif seccomp_t seccomp; /* Thread group tracking */ u32 parent_exec_id; u32 self_exec_id; /* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed, * mempolicy */ spinlock_t alloc_lock; #ifdef CONFIG_GENERIC_HARDIRQS /* IRQ handler threads */ struct irqaction *irqaction; #endif /* Protection of the PI data structures: */ spinlock_t pi_lock; #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_DEBUG_MUTEXES /* mutex deadlock detection */ struct mutex_waiter *blocked_on; #endif #ifdef CONFIG_TRACE_IRQFLAGS unsigned int irq_events; int hardirqs_enabled; unsigned long hardirq_enable_ip; unsigned int hardirq_enable_event; unsigned long hardirq_disable_ip; unsigned int hardirq_disable_event; int softirqs_enabled; unsigned long softirq_disable_ip; unsigned int softirq_disable_event; unsigned long softirq_enable_ip; unsigned int softirq_enable_event; int hardirq_context; int softirq_context; #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 /* journalling filesystem info */ void *journal_info; /* stacked block device info */ struct bio *bio_list, **bio_tail; /* VM state */ struct reclaim_state *reclaim_state; struct backing_dev_info *backing_dev_info; struct io_context *io_context; unsigned long ptrace_message; siginfo_t *last_siginfo; /* For ptrace use. */ 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 #ifdef CONFIG_CPUSETS nodemask_t mems_allowed; /* Protected by alloc_lock */ int cpuset_mem_spread_rotor; #endif #ifdef CONFIG_CGROUPS /* Control Group info protected by css_set_lock */ struct css_set *cgroups; /* cg_list protected by css_set_lock and tsk->alloc_lock */ struct list_head cg_list; #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 #ifdef CONFIG_PERF_EVENTS struct perf_event_context *perf_event_ctxp; struct mutex perf_event_mutex; struct list_head perf_event_list; #endif #ifdef CONFIG_NUMA struct mempolicy *mempolicy; /* Protected by alloc_lock */ short il_next; #endif atomic_t fs_excl; /* holding fs exclusive resources */ struct rcu_head rcu; /* * cache last used pipe for splice */ struct pipe_inode_info *splice_pipe; #ifdef CONFIG_TASK_DELAY_ACCT struct task_delay_info *delays; #endif #ifdef CONFIG_FAULT_INJECTION int make_it_fail; #endif struct prop_local_single dirties; #ifdef CONFIG_LATENCYTOP int latency_record_count; struct latency_record latency_record[LT_SAVECOUNT]; #endif /* * time slack values; these are used to round up poll() and * select() etc timeout values. These are in nanoseconds. */ unsigned long timer_slack_ns; unsigned long default_timer_slack_ns; struct list_head *scm_work_list; #ifdef CONFIG_FUNCTION_GRAPH_TRACER /* Index of current stored adress 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 */ unsigned long stack_start; };
一、sigaction
struct sigction{
??void(*sa_handler)(int); # sa_handler是信號的處理函數(shù)對應的指針
??sigset_t sa_mask; # sa_mask是信號掩碼,表示該處理哪些信號,哪些信號暫時不用處理
??int sa_flags;
??void(*sa_restorer)(void);
};
二、 時間相關(guān)的數(shù)據(jù)結(jié)構(gòu): timeval;itimeval(記錄定時器的數(shù)據(jù))
1、sigaction、查詢或設置指定信號處理方式,return原來信號的處理方式
2、signal、設置指定信號的處理方式,通過handle(函數(shù)指針),調(diào)用函數(shù)作為信號的處理方式
3、kill、給進程(pid)發(fā)送信號(sig)
4、raise、給自身發(fā)送信號(sig)
5、sigemptyset、信號集初始化(清空信號集);sigfillset、初始化并加入所有的信號;sigaddset、將制定的信號加入信號集中;sigismenber、通過*set定位,查詢signum是否在指定的信號集。
1、sleep、將進程暫停運行指定時間(seconds),可以被其他優(yōu)先級更高的信號或中斷打斷
2、alarm、在指定間隔時間之后周期性給進程發(fā)送信號 SIGALRM。
3、setitimer、設置定時器
4、getitimer、獲取指定類型的定時器,通過*value指針調(diào)用指定類型定時器
注:定時器定時需要重復對 timeval;itimeval兩個結(jié)構(gòu)體進行操作。
1、UNIX時間戳(Epoch Time):Unix時間戳(英文為Unix time, POSIX time 或 Unix timestamp)是從 Epoch(1970年1月1日00:00:00 UTC)開始所經(jīng)過的秒數(shù),不考慮閏秒。 timeval記錄就是Epoch Time至今的時間間隔,進度到毫秒。
2、 itimeval 結(jié)構(gòu)體記錄的是定時器剩余時間