Book Image

Real-World SRE

By : Nat Welch
Book Image

Real-World SRE

By: Nat Welch

Overview of this book

Real-World SRE is the go-to survival guide for the software developer in the middle of catastrophic website failure. Site Reliability Engineering (SRE) has emerged on the frontline as businesses strive to maximize uptime. This book is a step-by-step framework to follow when your website is down and the countdown is on to fix it. Nat Welch has battle-hardened experience in reliability engineering at some of the biggest outage-sensitive companies on the internet. Arm yourself with his tried-and-tested methods for monitoring modern web services, setting up alerts, and evaluating your incident response. Real-World SRE goes beyond just reacting to disaster—uncover the tools and strategies needed to safely test and release software, plan for long-term growth, and foresee future bottlenecks. Real-World SRE gives you the capability to set up your own robust plan of action to see you through a company-wide website crisis. The final chapter of Real-World SRE is dedicated to acing SRE interviews, either in getting a first job or a valued promotion.
Table of Contents (13 chapters)

Units of scale

One last thing to consider when thinking about Linux and the cloud is the scale of things. Jeff Dean, a prominent computer scientist at Google, gave a talk in 2002 about latency numbers every engineer should know based on research from Peter Norvig (, another very prominent computer scientist at Google.

These numbers have been updated and represented by many since then. The most recent numbers I could find are from Colin Scott (, a software engineer at Google, who has been guessing how the numbers change based on historical trends in computer hardware. I got the following numbers from Jonas Bonér, the creator of akka and the CTO of Lightbend, and modified the table (





L1 cache reference

0.5 ns


L2 cache reference

7 ns


Mutex lock/unlock

25 ns