Code tuning strategies
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The document discusses strategies for code tuning to improve performance. It covers identifying areas of inefficiency through profiling, focusing on "hot spots" that consume the most runtime. Common sources of inefficiency include input/output, paging, system calls and interpreted languages. The document recommends an iterative process of measurement, optimization of hot spots, and remeasurement to evaluate improvements. It also cautions that code tuning should only be done after establishing correctness, quality and design to avoid detracting from the primary goals of development.
![Contd….
Consider the following code that initializes a 10-element
array:
(a) for i = 1 to 10
a[ i ] = I
end for
(b) a[ 1 ] = 1
a[ 2 ] = 2
a[ 3 ] = 3
a[ 4 ] = 4
a[ 5 ] = 5
a[ 6 ] = 6
a[ 7 ] = 7
a[ 8 ] = 8
a[ 9 ] = 9
a[ 10 ] = 10
Prof. Asha N
6](https://image.slidesharecdn.com/code-tuningstrategies-140217024622-phpapp01/85/Code-tuning-strategies-6-320.jpg)
![Contd…
C++ Example of Straightforward Code to
Sum the Elements in a Matrix
sum = 0;
for ( row = 0; row < rowCount; row++ ) {
for ( column = 0; column < columnCount; column++ ) {
sum = sum + matrix[ row ][ column ];
}
}
Prof. Asha N
11](https://image.slidesharecdn.com/code-tuningstrategies-140217024622-phpapp01/85/Code-tuning-strategies-11-320.jpg)
![Contd…
C++ Example of an Attempt to Tune Code
to sum the Elements in a Matrix
sum = 0;
elementPointer = matrix;
lastElementPointer = matrix[ rowCount - 1 ][ columnCount - 1 ] + 1;
while ( elementPointer < lastElementPointer ) {
sum = sum + *elementPointer++;
}
Prof. Asha N
12](https://image.slidesharecdn.com/code-tuningstrategies-140217024622-phpapp01/85/Code-tuning-strategies-12-320.jpg)
Code tuning strategies
- 1. Code-Tuning Strategies Code Complete Author : Steven C. McConnell. Prof. Asha N 1
- 2. Code-Tuning Strategies 1. 2. 3. 4. 5. Performance Overview Introduction to Code Tuning Kinds of Fat and Molasses Measurement Iteration Prof. Asha N 2
- 3. 1. Performance Overview Code tuning is one way of improving a program’s performance Quality Characteristics and Performance “Performance is only loosely related to code speed”. To the extent that you work on your code’s speed, you’re not working on other quality characteristics. work on speed may hurt performance rather than help it Performance and Code Tuning When efficiency is chosen as a priority - think about efficiency from each of these view points Program Requirements Program Design Class and Routine Design Operating-System Interactions Code Compilation Hardware Code Tuning Prof. Asha N 3
- 4. 2. Introduction to Code Tuning Code Tuning - mastering the art of writing efficient code, One attraction is that a routine that executes in 20 microseconds, tweak a few lines, and reduce the execution speed to 2 microseconds Prof. Asha N 4
- 5. Contd… The Pareto Principle The Pareto Principle also known as the 80/20 rule, states that you can get 80 percent of the result with 20 percent of the effort. The principle applies to a lot of areas other than programming, but it definitely applies to program optimization. Old Wives’ Tales some common misapprehensions about code tuning Reducing the lines of code in a high-level language improves the speed or size of the resulting machine code—false! Prof. Asha N 5
- 6. Contd…. Consider the following code that initializes a 10-element array: (a) for i = 1 to 10 a[ i ] = I end for (b) a[ 1 ] = 1 a[ 2 ] = 2 a[ 3 ] = 3 a[ 4 ] = 4 a[ 5 ] = 5 a[ 6 ] = 6 a[ 7 ] = 7 a[ 8 ] = 8 a[ 9 ] = 9 a[ 10 ] = 10 Prof. Asha N 6
- 7. Contd…. Certain operations are probably faster or smaller than others—false! What was true on one machine with one set of tools can easily be false on another machine with a different set of tools. You should optimize as you go—false! Focusing on optimization during initial development detracts from achieving other program objectives. A fast program is just as important as a correct one—false! When to Tune It’s hardly ever true that programs need to be fast or small before they need to be correct Use a high-quality design. Make the program right. Make it modular and easily modifiable so that it’s easy to work on later. When it’s complete and correct, check the performance. If the program lumbers, make it fast and small. Don’t optimize until you know you need to. Prof. Asha N 7
- 9. 3. Kinds of Fat and Molasses In code tuning you have to profile the program to know with any confidence which parts are slow and fat Common Sources of Inefficiency Input/output operations Paging System calls Interpreted languages Errors Prof. Asha N 9
- 10. 4. Measurement small parts of a program usually consume a disproportionate share of the run time, So measure your code to find the hot spots. Once you’ve found the hot spots and optimized them, measure the code again to assess how much you’ve improved it Prof. Asha N 10
- 11. Contd… C++ Example of Straightforward Code to Sum the Elements in a Matrix sum = 0; for ( row = 0; row < rowCount; row++ ) { for ( column = 0; column < columnCount; column++ ) { sum = sum + matrix[ row ][ column ]; } } Prof. Asha N 11
- 12. Contd… C++ Example of an Attempt to Tune Code to sum the Elements in a Matrix sum = 0; elementPointer = matrix; lastElementPointer = matrix[ rowCount - 1 ][ columnCount - 1 ] + 1; while ( elementPointer < lastElementPointer ) { sum = sum + *elementPointer++; } Prof. Asha N 12
- 13. 5. Iteration keep trying until u improve to an extent. Prof. Asha N 13