Linux: This Book Includes 4 Manuscripts. The Underground Bible to the unix operating System with Tools On Security and Kali Hacking to Understand Computer Programming, Data Science and Command Line

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Linux This Book Includes 4 Manuscripts The Underground Bible

Lottery Planning

Multilevel Feedback Queues
Algorithms of multi bursts with feedback ( multilevel feedback queues ) are
scheduling algorithms (using settings it can be reduced to any other
algorithm), but one of them is used in the implementation. In terms of
organizing data structures, this algorithm is similar to the conventional
multilevel queue algorithm: there are several queues of ready threads with
different priorities, with lower priority queue threads only running when all
upper-level queues are empty.
The differences between the two algorithms are:
❖
Flows are allowed to cross from level to level
❖
Flows in a line are united not by priority and the length of the use
interval flows with shorter intervals are in line with higher priority
Within all queues, except the lowest, use circular scheduling (the
lowest FIFO algorithm works). The different queues correspond to different
lengths of time quanta - the higher the priority, the shorter the quantum
(usually the length of the quantum for adjacent queues is halved). If the
flow has exhausted its time quantum, it moves to the tail of the queue with a

lower priority (and with a longer quantum). As a result, flows with shorter
intervals (such as limited I / O) remain with high priority, and flows with
longer intervals extend their time. You can also automatically move non-
managed streams from the lower tier to the tier in and out.
Lottery Planning
Planning lottery ( lottery scheduling ) - algorithm, easy to understand and
easy to implement and it has great potential. The idea of lottery planning is
that:
❖
The stream receives an insane amount of lottery tickets, each of
which entitles the processor to use T for a time
❖
The scheduler selects one lottery ticket at random over a period of
time T
❖
The winnable stream gets control to the next dra w
Lottery planning allows you to:
❖
Emulate circular scheduling, giving each stream the same number
of tickets
❖
Emulate priority scheduling, distributing tickets according to
stream priorities
❖
Emulate SRTCF - give short streams more tickets than long ones (if
the stream received at least one ticket, it would not starve)
❖
Ensure that the processing time is split between threads - give each
thread a number of tickets proportional to the fraction of processor
time it needs to allocate (for example, if there are three threads, and it
is necessary for thread A to occupy 50% of the processor and
threads B and C, 25 each %, it is possible to give stream A two tickets
and flows B and C one each)
❖
To change priorities, selecting and adding tickets on the go
Although most of these tasks can be solved by lottery planning, only
approximately, with some likelihood, in practice, they are quite

satisfactory. The longer the system works, the closer the results will be to
the theoretical values (by the law of large numbers). In fact, lottery
planning takes advantage of the fact that all planning ideology is largely
heuristic since one cannot accurately predict the nature of flow behavior in
the system .

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