Definition 1 Efficiency Eux of computer system is measured by number of
instructions required to perform to the total number of instructions performed by
computer system.
Naturally, efficiency Eux ! 1, while m ! 0, and, no matter what frequency a
processor is if m ! n, Eux ! 0.
Regretfully, it is a case for current state of the art in computer systems and
especially embedded computer systems. What it means for embedded systems
especially?
For various systems, it means that
• Application of Java, or use of modified standard operating system, unavoidably
reduces efficiency and, above all, runs out our computer batteries for nothing;
• For military systems, an availability and reactiveness is substantially lower than
it could be;
• For office systems, nowadays, the employees are sitting and waiting for
Windows or Cisco service more than they actually work.
Leaving further comments about efficiency for system software research and PhD
projects, let’s concentrate on implementation of hardware instructions in terms of
time.
17.5 Hardware Performance
One of the simplest information processing systems is a simple turing machine—
(http://ideonexus.com/2009/02/05/javascript-turing-machine/); it demonstrates in
principle almost minimum of hardware required to perform information processing.
Turing machine usually is drawn similar to mine (Fig. 17.8).
Head is moving left and right accordingly instructions stored on the tape and
modifies content of the tape. Surprisingly, if an algorithm for problem exists, it is
very possible to calculate it and complete.
Turning machine was invented as a model well before Von Neumann’s architecture. The latter one assumes that programs and data are placed on the same tape
and head Q might perform instructions. More details about this machine might be
i
j
k
l
…
Q
Fig. 17.8 A-la turing for
performance evaluation
17.4 SSW-HW Performance Model
227
instructions required to perform to the total number of instructions performed by
computer system.
Naturally, efficiency Eux ! 1, while m ! 0, and, no matter what frequency a
processor is if m ! n, Eux ! 0.
Regretfully, it is a case for current state of the art in computer systems and
especially embedded computer systems. What it means for embedded systems
especially?
For various systems, it means that
• Application of Java, or use of modified standard operating system, unavoidably
reduces efficiency and, above all, runs out our computer batteries for nothing;
• For military systems, an availability and reactiveness is substantially lower than
it could be;
• For office systems, nowadays, the employees are sitting and waiting for
Windows or Cisco service more than they actually work.
Leaving further comments about efficiency for system software research and PhD
projects, let’s concentrate on implementation of hardware instructions in terms of
time.
17.5 Hardware Performance
One of the simplest information processing systems is a simple turing machine—
(http://ideonexus.com/2009/02/05/javascript-turing-machine/); it demonstrates in
principle almost minimum of hardware required to perform information processing.
Turing machine usually is drawn similar to mine (Fig. 17.8).
Head is moving left and right accordingly instructions stored on the tape and
modifies content of the tape. Surprisingly, if an algorithm for problem exists, it is
very possible to calculate it and complete.
Turning machine was invented as a model well before Von Neumann’s architecture. The latter one assumes that programs and data are placed on the same tape
and head Q might perform instructions. More details about this machine might be
i
j
k
l
…
Q
Fig. 17.8 A-la turing for
performance evaluation
17.4 SSW-HW Performance Model
227