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Max-IT (CPU)
Max-IT
(CPU) improves application
response times by ensuring that
users and programs receive their
rightful (fair) share of the CPU
resources, and without being
stifled by rogue (runaway)
programs.
The
Facts
- Due to
design limitations and lazy
programming techniques, many
applications often exhibit
adverse behavioral trends; they
monopolize the server’s
processors and deny other
running applications their
rightful share of CPU cycles.
Such applications are often
referred to as “rogue” or
“runaway” applications.
- By definition, a rogue or
runaway application is one whose
thread(s) use up excessive
amounts of CPU resources. In
other words, they consistently
remain in the RUNNING state for
the entire lifetime of their
allotted time slices. A time
slice is often referred as
“quantum”, and its value is
typically 10 to 15 milliseconds
(hardware-dependent) under
Windows 2000/2003.
- The Windows scheduler does not
include a fair-sharing
mechanism; hence, it does not
prevent rogue applications from
consuming all the CPU time.
- “Priority boosting” performed by
Windows’ built-in balance set
manager does not effectively
address CPU starvation caused by
runaway applications, especially
in Terminal Server environments.
- From a CPU management
perspective, the thread
priorities of interest are
WAITING, READY, and RUNNING. In
the case of a word processor,
the latter could be waiting for
user input. As soon as it
receives input, it is ready to
run. And as soon as the
processor becomes free, it will
run
- Given
two threads in the READY state,
the scheduler will ALWAYS favor
the process with the higher
priority level over the other.
Next: Max-IT (CPU) - The Problem
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