2 Linux

1 2060(process)MULTICSIBMCTSS/360

1.

2.

(concurrency)(parallel)

2

LinuxPID(process ID) PID UID GID

UIDGID4 UIDuideuidsuidfsuid GIDgidegidsgidfsgid uid=euid=fsuidgid=egid=fsgid

uidgideuidegiduidgidsuidsgidfsuidfsgid

(context)LinuxPCB(process control block)(text segment)(data segment)(stack)

(process table)PCB2-1

2-1

PIDPCB(PIDhash)PCB

3

LinuxLinux29killkillpg

3-1

3-1 Linux

3

(ready)

(blocked)

task_structPIDinclude/Linux/sched.h

task_struct (include/linux/sch.h)

task_struct state Linux5:

2-2 Linux

RUNNING RUNNING

Linux

UNINTERRUPTABLE

INTERRUPTABLE

STOPPED (SIGSTOPSIGSTPSIGTTIN SIGTTOU) ptrace

ZOMBIE

(scheduler) Linuxschedule() schedule()C

fork()do_fork()fork fork() PID

fork()RUNNING RUNNINGschedule()

sleep()PCB sleep()schedule().

RUNNING

exit()SIG_KILLZOMBIE schedule()

STOPPED SIG_KILLSIG_CONTSTOPPED

PCB (FIFO)(round-robin)(Linux)

Linux(10ms) schedule()goodness() Linux

4 Linux0ABABBA

task_struct struct task_struct *p_pptr, *p_cptr, *p_ysptr, *p_osptr;p_pptr: parent ()p_cptr: child ()p_ysptrp_osptr

PCBp_cptrPCBPCBp_pptrPCB 2-3

2-3

task[]task_structPid hashpidhashrun_listprio_array

currentcurrentinittask_struct: INIT_TASK

start_kernel()0init_task()0 0

fork()fork Linuxfork() Afork()Bfork()AB Afork()PIDBfork()0fork()

fork()? fork() PCB .forkfork.swf

PCBPCB

vfork()SIG_STOP

fork() Linuxfork+exec execve() execve()

5

Linux 1. POSIX

() Linux

2. (FIFO) LinuxFIFO(named pipe)

FIFOfirst infirst out FIFO FIFOread()write()

3. IPC IPCinterprocess communication . IPCColumbus UnixUnix

IPC

(1)

(2)

(3) IPC

0101 0 25

11

IPC IPC

6 Linux ()

ABx1

1 Linux

, ,CPU (,)

1. 2. euidegiduidgid euidegid uideuidgidegidrootuidgideuidegid 3 suidsgidPOSIXuidgiduidgid 4. fsuidfsgiduidgidLINUX euidegidNFSNFSfsuidfsgid:;;PCBPCBp_osptr PCBPCBp_ysptrPCB p_cptrforkforkLinux fork()fork()PID fork()fork()fork()PIDfork()0

( ) 001

ABCPUx2 ABx1 x1