Information about the processes and flows in the system is stored in special
data
structures, which are called process control blocks and flow control
blocks. These structures are very important for the OS because on the basis
of their information system manages processes.
Managing power flow ( Thread Control Block or TCB ) to an active flow,
ie that which is in a state of readiness, expectation or execution. This block
may contain the following information:
❖
Flow identity (usually its unique identifier)
❖
Flow processor status:
custom processor registers, instruction
counter,
the stack pointer
❖
Flow planning informatio n
Table streams - is a list or array of flow control units.
It is located in a
protected area of the OS memory.
The managing unit process
( Process Control Block or PCB ) corresponds to the process that is present
in the system. Such block may contain:
❖
Process identity (unique identifier
information about other
processes related to adan)
❖
Information about the threads that are running in the address space
of the process (for example, pointers to their control blocks)
❖
Information that allows you to determine the rights of a process to
use different resources (for example, the user ID that created the
process)
❖
Process address
allocation information
❖
Information about I / O resources and files used by the process
Process And Flow Images
The totality of the information displayed in the memory process called the
image process , and all information flow (thread image). The image process
includes:
❖
Process
control unit
❖
User code
❖
User data (global program data common to all threads)
❖
Process flow pattern information
The user program code, user data, and stream information are loaded into
the process address space. The image process is generally not a continuous
section
of memory, its parts are unloaded to disk. The streaming image
includes:
❖
Flow control unit
❖
Kernel stack (the flow stack used when executing kernel flow code)
❖
User stack (stream stack available in user mode)
