1. CS 286 Computer Architecture & Organization
Evolution in clock-cycle rate in different Intel CPU architectures
i486
1989 through1992
Pentium (P5/P54)
1993 through 1997
Pentium II/Pro
1997 through 1998
16MHz
66MHz
100MHz
133MHz
166MHz
200MHz
233MHz
233MHz
266MHz
300MHz
56.2% increase
55.0% increase
33.0% increase
24.8% increase
19.8% increase
16.5% increase
14.1% increase
12.4% increase
25MHz
32.0% increase
33MHz
21.2% increase
As C.C. rate increases,
improvement becomes
more difficult
40MHz
25.0% increase
50MHz
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2. CS 286 Computer Architecture & Organization
Evolution in clock-cycle rate in the recent Intel CPU architectures
Pentium 4 (2000 through 2008)
Pentium D (2005 through 2008)
Core-2 Quad (2006 through present)
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3. Instruction-Execution
CS 286 Computer Architecture & Organization
Another performance metric: CPI (Cycles Per Instruction)
(e.g., “ADD”)
(3 + 10)
(e.g., “FP-MULT”)
(3.14  (10.2)2)
1 instruction
1 instruction IF ID EX WB IF ID
EX1
EX21
   WB
1 cycle
1 cycle
1 cycle
1 cycle
1 cycle
1 cycle
1 cycle
1 cycle
4 cycles
24 cycles
IF – Instruction Fetch
ID – Instruction Decoding
EX – Instruction Execution
WB – Result Write-Back
Instruction-Execution
Phases
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4. CS 286 Computer Architecture & Organization
Another performance metric: CPI (Cycles Per Instruction)
CPI = The (average) number of the processor clock cycles required to complete
one processor instruction.
Example
CPI = ( )/3 = 6.0
Number of Processor Cycles (time)
Number of Instructions
1 instruction IF ID EX EX ME WB 3 2 IF ID EX EX EX ME WB IF ID EX ME WB 1
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5. CS 286 Computer Architecture & Organization
What does “average CPI” mean?
= The average number of processor clock-cycles per instruction
These numbers
are different for
each processor
Each processor has many different instructions
How can we calculate the average?
Types of Instructions
Examples
Cycles Reqd.
Frequency
Memory Access Instructions
LOAD
, STORE 5 4 24 8 6 10
0.32 (32%)
0.21
0.18
0.05
0.10
0.12
0.02
Integer Arithmetic Instructions
ADD
, SUB
Logic Calculation Instructions
AND
, OR
, XOR
Floating-Point Arithmetic Instructions
FP-MULT
Jump and Branch Instructions JP
, BRZ
, BRNZ
Bit-Manipulation Instructions LS
, RS
Other Instructions
NOP
, HLT
, DI
Average CPI = (50.32)+(40.21)+(40.18)+(240.05)
+(80.1)+(60.12)+(100.02)
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