?2? ???? ?? (Process Management)

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?2? ???? ?? (Process Management)

• ????
• ???? ????(program in execution)
• CPU time, memory, files, I/O devices ? ?? ??
• ???? ???? (the unit of work)
• ??
• 1. ??? ????(user process) - user code ??
• 2. ??? ????(system process) - system code ??
• ???? ??
• ??? ????? ??? ????? ??? ??
• ???? ????
• ?????? ??? ?? ??
• ?????? ?? ??
• ?????? ????(deadlock)??

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Chapter 3. ???? ??(Process Concept)

• Questions of the day
• ????? ? ? ?? ?????
• Linux ? ????? ???? PCB(Process Control Block) ???
  ????
• Unix/Linux ????? ???? ??? ????
• ???? ????? ???? ???
• ????? ??(context)? ??? ???
• ??? ??? ??? ??? ? ?? ???-??? ??? ?? ?????? ???
• ?? ?? ???-??? ?? (bounded buffer
  producer-consumer problem) ?????

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???? ??(Process Concept)

• ?? 1 program ?? ? ??? multiple program? ?? ??
• ???? (The Process)
• ???? ?? ?? ??(Current activity)
• PC(Program Counter)
• ???? ?
• ??(stack) ????, ????, ????, ???? ?
• ??? ??(data section) ????
• ???? ??(Process State)
• ??(new)
• ??(running) CPU? ??
• ??(waiting) I/O??? signal ???
• ??(ready) Processor? ?? ??? ?
• ??(terminated)

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Process in Memory
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???? ??(Process State)
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(??) Linux ?? ??? ??

• ??? ????? 4GB ?? ??? ??
• ? ????? 3GB ??
• ??? 1GB? ?? ????? ?? ????? ?? ???? ??

cat /proc/1/maps
BSS(Block Started by Symbol)
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(??) Linux ??? ?? ????

• task_struct ????? struct mm_struct mm
• /usr/src/kernels/linux-2.6.35.6/include/linux/sche
  d.h (1256? Fedora Linux 2.6.38.6)
• /usr/src/kernels/linux-2.6.35.6/include/linux/mm_t
  ypes.h (222?, 131?)
• ??? ?????

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???? ??(Process Concept)

• ???? ?? ??(Process Control Block) ? /proc ??
• ? ????? PCB? ???
• Solaris 10 Unix /usr/include/sys/proc.h (99?)
• Fedora Linux /usr/src/kernels/linux-2.6.38.6/incl
  ude/linux/sched.h (1193?)
• PCB
• ???? ?? new, ready, running, waiting, halted
• ???? ??? next instruction? ??
• CPU????? accumulator, index register, stack
  pointers, ?? registers, condition-code
• CPU??? ?? priority, pointers to scheduling
  queues
• ??? ?? ?? base and limit registers, page tables,
  segment tables
• ?? ?? time used, time limits, account numbers,
  job, process
• ??? ?? ?? I/O devices list allocated to the
  process, list of open files
• ???(Threads)
• a process a single thread of execution (one
  task)
• ?? ?? OS?? multiple threads of control
  (multitasks at a time) ??

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Process Control Block (PCB)
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Linux task_struct ???

• ???? ?? ?? ??
• ????? ???? task_struct ???? ?? ????? ?? ???
  ???? ??
• ?? ?????? ??? ??
• /usr/src/kernels/linux-2.6.38.6/include/linux/sche
  d.h (1193?)
• ??? ID, ?? ??, ?? ??,??, ???, ???, ????,CPU ???
  ? ?? ????? ? ??? ???? ?? ??? ??
• alloc_task_struct ???? ?? ?? ??? ????? 8KB? ????
  ???? ?????? ?? ??? ??? ??
• current ?? ???? ?? ???? ???? ??
• /usr/src/kernels/inux-2.6.38.6/arch/x86/include/as
  m/current.h (17?)

?? ??? ???? ?????
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Linux task_struct ???

• ??? ??? ??? ???
• p_opptr? p_pptr ?? ???
• p_oppr Original Parent
• p_cptr ??, p_ysptr ??, p_osptr ?
• ??? ???? ?? ????? ?? ?? ?? ???? ??
• SET_LINKS ???? ???? ???
• REMOVE_LINK ???? ???? ???

struct task_struct p_opptr, p_pptr, p_cptr,
p_ysptr, p_osptr
struct task_struct next_task, prev_task
task_struct ???
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???? ????(Process Scheduling)

• ???? ?(Scheduling Queues)
• ?? ? (job queue) memory ?? ???? ?(disk??)
• ?? ? (ready queue) CPU? ?? ???? ?
• ?? ? (device queue() ??? ???? ?
• ?? ?? (queueing diagram) ?? 3.7
• ????(Schedulers)
• ?? ????(long-term scheduler, job scheduler)
• pool ? memory(degree of multiprogramming)
• Unix ?? ??? ????? ??
• ?? ????(short-term scheduler, CPU scheduler)
• CPU ?? must be very fast
• ?? ????(medium-term scheduler)
• swapping
• degree of multiprogramming? ??
• memory ? backing store

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???? ??? ??? ?? ?
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???? ????? ???? ?? ??
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?? ??? ?? ????(Medium Term Scheduling) ??
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???? ????(Process Scheduling)

• ?? ??(Context Switch)
• CPU? ? process?? ?? process? switch? ?
• save the state of the old process CPU? ???
  ??(PCB??)
• load the saved state for new process CPU? ???
  ??(PCB??)
• pure overhead performance bottleneck ? threads?
  ??
• context-switch time 1-1000microsecond
• address space ?? ?? memory ????? ??

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? ?????? ?? ?????? CPU Switch
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????? ?? ?????(Operations on Processes)

• ???? ??(Process Creation)
• ???? ?? ??? ?? fork, exec, CreateProcess, etc.
• ?? ????
• ?? ???? ?? ??? ?? ????? ??(memory, files) ??
• ? ???? ?? ? ???
• ?? ??
• ?? ??? ?? ? ?? ??? wait system call?

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???? UNIX System? ???? ??
ps