The transition of flows between standby and readiness states is based
on
task planning or
flow planning. When scheduling threads, determine
which threads need to be restored after completing the I / O operation, how
to organize the system expectations.
The transition between standby and
execution states requires a processor
time schedule . Based on the algorithms of such planning, determine which
of the finished threads need to be executed at a specific time, when do you
need to interrupt the execution of the thread to switch to another ready
thread and so on.
With regard to systems that implement the process model, it is customary to
talk
about the state of processes, not flows, and the planning of
processes; in fact, the states of the process in this case clearly correspond to
the states of its single flow.
Description Of Processes And Flows
As we already know, one of the main tasks of the operating system is the
allocation of resources between processes and flows.
These resources are
primarily CPU time (distributed between streams during scheduling), I / O,
and memory (shared between processes) .
To manage the allocation of resources, the OS must support data structures
that contain information describing processes, flows, and resources. The
following data structures include:
❖
Resource allocation tables: memory tables, I / O tables, file tables,
etc.
❖
Process tables and flow tables that provide information about the
processes and flows present in systems at a specific point in time
