Editor's note: Followup question with optimization enabled that times only the loop: Why is iterating though `std::vector` faster than iterating though `std::array`? where we can see the effect of ...

I'm working on a maven project. I'm trying to integrate jmh benchmarking into my project. The pom.xml of my maven project... <parent> <groupId>platform</groupId> <artifactId...

I have a few questions on STREAM (http://www.cs.virginia.edu/stream/ref.html#runrules) benchmark. Below is the comment from stream.c. What is the rationale about the requirement that arrays shoul...

How do I enable C++ demangling for the perf callgraph? It seems to demangle symbols when I go into annotate mode, but not in the main callgraph. Sample code (using Google Benchmark): #include &lt...

This code is an adaptation of this other one... It is an ugly code but the question is about "how to do a benchmark". The new console.time function measure the "real execution time" or is it not...

In Chandler Carruth's CppCon 2015 talk he introduces two magical functions for defeating the optimizer without any extra performance penalties. For reference, here are the functions (using GNU-sty...

According to JEP 230: Microbenchmark Suite, there exists a microbenchmark suite built-in to Java 12. The JEP explains that it's basically JMH, but without needing to explicitly depend on it using M...

I've encountered an interesting scenario. For some reason strip() against blank string (contains whitespaces only) significantly faster than trim() in Java 11. Benchmark public class Test { pub...

First I have the below setup on an IvyBridge, I will insert measuring payload code in the commented location. The first 8 bytes of buf store the address of buf itself, I use this to create loop-car...

I'm on an IvyBridge. I found the performance behavior of jnz inconsistent in inner loop and outer loop. The following simple program has an inner loop with fixed size 16: global _start _start: m...

I'm on IvyBridge, I wrote the following simple program to measure the latency of mov: section .bss align 64 buf: resb 64 section .text global _start _start: mov rcx, 1000000000 xor rax, rax loo...

I am trying to profile a code for execution time on an x86-64 processor. I am referring to this Intel white paper and also gone through other SO threads discussing the topic of using RDTSCP vs CPUI...

Out of this SO post resulted a discussion when benchmarking the various solutions. Consider the following code # global environment is empty - new session just started # set up set.seed(20181231) ...

I'm trying to understand better how memory works in .NET, so I'm playing with BenchmarkDotNet and diagnozers. I've created a benchmark comparing class and struct performance by summing array items....

I am checking on Celero git repository the meaning of DoNotOptimizeAway. But I still don't get it. Could you please help me understand it in layman's terms please. As much as you can. The celero...

For many years x86 CPUs supported the rdtsc instruction, which reads the "time stamp counter" of the current CPU. The exact definition of this counter has changed over time, but on recent CPUs it i...

Consider the following x86 assembly: ; something that sets rax mov rcx, [rdi] xor rax, rcx xor rax, rcx At the end of the sequence, rax has the same value as it had on entry, but from the point ...

I've recently discovered a huge difference between two macros: @benchmark and @time in terms of memory allocation information and time. For example: @benchmark quadgk(x -> x, 0., 1.) BenchmarkT...

I'm willing to write a code that makes my CPU execute some operations and see how much time does he take to solve them. I wanted to make a loop going from i=0 to i<5000 and then multiplying i by...

I want to understand what kind of optimizations Java does to consecutive for loops. More precisely, I'm trying to check if loop fusion is performed. Theoretically, I was expecting that this optimiz...

I want to get an accurate execution time in micro seconds of my program implemented with C++. I have tried to get the execution time with clock_t but it's not accurate. (Note that micro-benchmarkin...

I'm trying to measure the memory consumed when running the benchmark. I found out on the internet that I can use GC profiler to measure that. I tried but I don't understand the answer as well as se...

I'm using JMH to benchmark DOM parser. I got really weird results as the first iteration actually run faster than later iterations Can anyone explain why this happens? Also, what do percentil...

On an x86-64 Intel system that supports syscall and sysret what's the "fastest" system call from 64-bit user code on a vanilla kernel? In particular, it must be a system call that exercises the sy...

Let's say I have a function that I plan to execute as part of a benchmark. I want to bring this code into the L1 instruction cache prior to executing since I don't want to measure the cost of I$ mi...