---
title: "Write barrier"
chunk: 1/1
source: "https://en.wikipedia.org/wiki/Write_barrier"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T11:40:52.597051+00:00"
instance: "kb-cron"
---

In operating systems, write barrier is a mechanism for enforcing a particular ordering in a sequence of writes to a storage system in a computer system.  For example, a write barrier in a file system is a mechanism (program logic) that ensures that in-memory file system state is written out to persistent storage in the correct order.


== In garbage collection ==
A write barrier in a garbage collector is a fragment of code emitted by the compiler immediately before every store operation to ensure that (e.g.) generational invariants are maintained.


== In computer storage ==
A write barrier in a memory system, also known as a memory barrier, is a hardware-specific compiler intrinsic that ensures that all preceding memory operations "happen before" all subsequent ones.


== See also ==
Native Command Queuing


== References ==


== External links ==
Barriers and journaling filesystems (LWN.net, May 21, 2008)