Tasks task
- managed by task_struct
- Job ID, there pid, tgid
-PID & TPID difference
getpid is acquired in the process descriptor task_struct tgid (thread group identifier), the pid (process identifier) is to manage all system processes id
Signal Processing
Processing status:
-blocked blocked, not processed
-pending wait, do not deal with
-sighand function by processing signals
Task state: (a geometric square 2)
#define TASK_DEAD 64
#define TASK_WAKEKILL 128
#define TASK_WAKING 256
#define TASK_PARKED 512
#define TASK_NOLOAD 1024
#define TASK_NEW 2048
#define TASK_STATE_MAX 4096
Sleep:
- can interrupt sleep patterns;
- uninterruptible sleep mode
First, check the running status information
1. Display the front CPU 10 of processes;
ps auxw|head -1;ps auxw|sort -rn -k3|head -10
2. Display of processes before Mem 10
ps auxw|head -1;ps auxw|sort -rn -k4|head -10
3.dstat usage
dstat -c
4.top
Second, inter-process relationships
-parent process
-children process
-sibling process
Third, Process Rights
objective/subjective
cred/real_cred ##cred<-> subjective; Real_cred<->objective
1)用户和用户组控制权限
- uid,gid
-euid ,egid
-fsuid,fsgid
2） capabilities 可以让普通用户获得更高权限，同时又不赋予root权限；
-cap_permited
-cap_effective
-cap_inheritable
-cap_bset
-cap_ambient ##解决cap_inheritable短板。
四、内存管理
mm_struct
1.用户态函数栈
-后进先出原则，即函数调用通过栈完成；
-入栈（push）和出栈(POP) 都是从栈顶进入，栈都是从高地址往低地址，往下增长的结构
-32位 叫ESP(栈顶) 和EBP（栈基），用的全部是函数栈；
-64位叫 RSP 和RBP，前6个使用寄存器；其他用函数栈；
-栈都是在内存空间完成
2. 内核态函数栈, 和进程运行有关。
- 32位；定义：arch/x86/include/asm/page_32_types.h
-PAGE_SIZE:4K;8k
-64位；定义：arch/x86/include/asm/page_64_types.h
-PAGE_SIZE:8k,16k,起始地址为8192的整数倍
-内核的代码Union将Thread_info和stack 放在一起，代码路径：include/linux/sched.h
-代码最高地址端，存放在另一个结构，pt_regs内；
-32位内核栈用thread_info来关联task_struct, 64位用per-CPU