performance optimization of C++

Tools for detect time killer

• OProfile
• PAPI

Tips for Performance Improvement Code Optimization

• Optimize Your Code using Appropriate Algorithm
• Optimize Your Code for Memory
• Using operators
• If Condition Optimization
  • if (a && b)， place b first if b is more likely to be false
• Problems with Functions
• Optimizing Loops
  • It is faster to test if something is equal to zero than to compare two
    different numbers.
• Reference
  • http://www.thegeekstuff.com/2015/01/c-cpp-code-optimization
  • http://stackoverflow.com/questions/2030189/general-c-performance-improvement-tips

memory allocate on stack or heap

Allocate memory on stack is more faster then heap cause of different architecture.
The heap is a far more complicated data structure than the stack.

Ref:

• http://stackoverflow.com/questions/2264969/why-is-memory-allocation-on-heap-much-slower-than-on-stack
• http://stackoverflow.com/questions/4974617/what-is-more-efficient-stack-memory-or-heap
• http://stackoverflow.com/questions/161053/which-is-faster-stack-allocation-or-heap-allocation

vector vs array

• Have same assembly instruction
  • index operation is same
  • dereference operation is same
  • increment operation is same
  • http://stackoverflow.com/questions/381621/using-arrays-or-stdvectors-in-c-whats-the-performance-gap
• But there are some attributes make vector slower than C array
  • Vector possible to store data in non-continuous chunk of memory
  • Vector allocate memory on heap always
  • http://assoc.tumblr.com/post/411601680/performance-of-stl-vector-vs-plain-c-arrays
• Another performance test between vector , boost array and C array
  • http://www.cnblogs.com/mudoot/articles/boost_array_0001.html

Use the right container

• more container compare and select
  • vector is good at read data
  • list is good at insert and remove data
  • deque has good balance for read, insert and remove data
  • http://www.cppblog.com/sailing/articles/161659.html
• reference
  • http://stackoverflow.com/questions/3664272/is-stdvector-so-much-slower-than-plain-arrays

Some tips when using C++

class Foo
{
    const BigObject & bar();
};

BigObject obj = foo.bar();  // OOPS!  This creates a copy!
const BigOject &obj = foo.bar();  // does not create a copy

some books

• Effective C++
• More Effective C++
• Effective STL
• C++ Coding Standards
• Efficient C++: Performance Programming Techniques

Know some compile and linker options

• gcc

Reference

• https://en.wikibooks.org/wiki/Optimizing_C++
• http://agner.org/optimize/optimizing_cpp.pdf
• http://www.artima.com/cppsource/how_to_go_slow.html
• https://github.com/fffaraz/awesome-cpp
• https://notabug.org/koz.ross/awesome-c
• https://github.com/jobbole/awesome-c-cn