-
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
