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C Speed Optimization Checklist

This is a list of general-purpose optimizations for C programs, from the most impactful to the tiniest low-level micro-optimizations to squeeze out every last bit of performance. It is meant to be read top-down as a checklist, with each item being a potential optimization to consider. Everything is in order of speed gain.

Algorithm && Data Structures

Choose the best algorithm and data structure for the problem at hand by evaluating:

time complexity

What is an "arena" in memory allocation?

I first leanred about "arena" when I was trying to understand the internal of [glibc malloc][glibc-alloc] around 2010, but I [later realized][trend] the concept is narrowly defined [in][arena1] [other][arena2] [context][arena3]. This blog post explains the difference in definition and the limitations in the so-called "arena allocators" we use today.

Background: why is malloc needed?

Every atomic object has a timeline (TL) of writes:
- A write is either a store or a read-modify-write (RMW): it read latest write & pushed new one.
- A write is either tagged Relaxed, Release, or SeqCst.
- A read observes some write on the timeline:
  - On the same thread, future reads can't go backwards on the timeline.
  - A read is either tagged Relaxed, Acquire, or SeqCst.
  - RMWs can also be tagged Acquire (or AcqRel). If so, the Acquire refers to the "read" portion of "RMW".
Each thread has its own view of the world:

Shared write timelines but each thread could be reading at different points.

How to use channels across different processes in Go

A couple of code samples to show how a named pipe can be used to extend Go's channel paradigm for use between different processes running on a system.

interprocess1.go details a single byte channel.
interprocess2.go details a channel that passes slices of bytes.

Note that opening a write channel will return two channels -

PostgreSQL is Enough

Background and Cron Jobs

Automating Daily Reports, because fuck it, really...

Each day at our company, developers are required to document their activities, painstakingly jotting down their daily work and future plans. A monotonous chore that I just really dislike.

So now, there's a scribe for that :

	// defer.h
	// [email protected]
	// © 2025 Crash Override, Inc.
	// Licensed under the BSD 3-Clause license

	#pragma once
	#include <stdint.h>

	typedef struct n00b_defer_ll_t n00b_defer_ll_t;

	{
	"meta": {
	"theme": "professional"
	},
	"basics": {
	"name": "Serhii Ivanov",
	"phone": "+48572260756",
	"label": "Senior Software Engineer \| Golang \| Kubernetes \| SRE \| DevOps",
	"image": "https://avatars.githubusercontent.com/u/11349489?v=4",
	"summary": "Proactive software engineer with Golang as language of choice. I am used to wearing many hats and generally very flexible when investigating new roles.",

	#!/usr/bin/env bash
	set -ex

	PACKAGES=(
	neovim-git
	)

	# All this is basically to get around makepkg calling pacman with sudo
	# Otherwise we could just call `aur sync` and be done with it

	#!/bin/bash

	FW_MARK="$((RANDOM%2147483646 + 1))"
	if [ "$(ip -4 rule show fwmark ${FW_MARK})" ] \|\| [ "$(ip -6 rule show fwmark ${FW_MARK})" ]; then
	while [ "$(ip -4 rule show fwmark ${FW_MARK})" ] \|\| [ "$(ip -6 rule show fwmark ${FW_MARK})" ]; do
	FW_MARK="$((RANDOM%2147483646 + 1))"
	done
	fi
	TABLE="$((RANDOM%2147483396 + 1))"
	if [ ! "$(ip -4 route show table ${TABLE} 2>/dev/null \|\| echo 1)" = "1" ] \|\| [ ! "$(ip -6 route show table ${TABLE} 2>/dev/null \|\| echo 1)" = "1" ]; then