Big O notation is commonly used to describe algorithm performance. But modern hardware makes performance analysis much harder than it used to be. In this short article we give three interesting examples to illustrate the limits of big O notation.
All posts tagged performance
2-minute read: What is faster, std::endl or ‘\n’?
A few days ago I wrote a small app to illustrate one of the articles I was preparing. Basically the program was loading a file from the hard disk, sorting it, and then outputting to another file only unique values (by omitting duplicates). The function for writing unique values to a file looks like this:…
Talk: The Price of Dynamic Memory in C and C++
Ivica Bogosavljević from Johny’s Software Lab gave a talk on November 26th, 2020 as part of C++ User Group Osnabrück related to the performance price the developers pay when they are using dynamic memory in C and C++.
Use explicit data prefetching to faster process your data structure
When processing (searching, inserting etc) your data structure, if you are accessing it in random-access fashion, the performance will suffer due to many data cache misses. Read on how to use the explicit data prefetching to speed up access to your data structure.
Multitime: a small utility to measure your program’s runtime
Multitime is a tool that you can use to repeat a command several times, and get additional information about its runtime: mean, standard deviation etc. Read this short article to get you started,
Excessive copying in C++ and your program’s speed
We talk about C++ and its weakness for temporary objects and excessive copying. We also give some tips on how to avoid them and make your program faster.
Make your programs run faster: avoid expensive instructions
We will talk about expensive instructions in modern CPUs and how to avoid them to speed up your program.
Tune your program’s speed with profile guided optimizations
Profile guided optimizations are a compiler-supported optimization technique that is easy to use and will make your program run faster with little effort. Here you will learn how to enable it on your project and what kind of improvements you can expect.
Process polymorphic classes in lightning speed
We investigate what is the best way to store polymorphic objects in a container for fast access
The price of dynamic memory: Memory Access
If your program uses dynamic memory, its speed will depend on allocation time but also on memory access time. Here we investigate how memory access time depends on the memory layout of your data structure. We also investigate ways to speed up your program by laying out your data structure optimally.