CPU and Kernel Page Faults

More from The Backend Engineering Show with Hussein Nasser All episodes →

1. 

   17 Jun 2026 · 34 min

   Postgres is half as fast in Linux 7.0

   An aws engineer discovered a 50% regression in postgres throughput while testing the new Linux 7.0 kernel. The cause turns out to be massive TLB and page faults exacerbated by Postgres process-based design. In this backend engineering show episode I dive deep into how this was discovered, the root cause and the possible fixes and workarounds. Intermediate and Advanced Backend Engineering Course Bundlehttps://courses.husseinnasser.com/bundleMy Book, Root Cause: Stories and Lessons from Two Decades of Backend Engineering Bugs https://amzn.to/4cKfZhe 0:00 Intro2:30 The Discovery6:30…

2. 

   8 Jun 2026 · 32 min

   Don't let AI rob you

   A discussion about why many engineers still love the struggle, the mistakes, and the process of figuring things out themselves. This is how we grow and get better and stronger. Letting AI do everything (even though it can’t) robs us this feeling..

3. 

   15 Apr 2026 · 10 min

   New Book: Root cause

   I wrote a new book that has been in the works for years. It is called Root Cause , and it is for those who enjoy the art of backend engineering. Early in my career, 20 years ago, I built backend and database applications without fully grasping their inner mechanics. Performance issues, race conditions, bugs, and even data corruption often left me lost. Since that day, I resolved to truly understand how systems work. From networking protocols and intermediary proxies to backend services and various database engines. I made it a habit to follow every request on its journey through the dark…

4. 

   19 Jan 2026 · 46 min

   5 Backend Design Patterns for Managing Threads and Sockets

   In this video I introduce 5 different design patterns for building backend applications. Each mode explains how a socket listener is established, a connections are established and how threads and connections are managed to read, write and process requests.

5. 

   15 Dec 2025 · 47 min

   Page Tables

   Page tables provide the mapping between virtual memory and physical memory for each process. This means it needs to be as efficient and as fast as possible. I explore the inner workings of page tables in this episode. 0:00 Intro 2:00 Virtual Memory ⁃ ⁃ 8:00 MMU 10:00 Page Tables ⁃ ⁃ ⁃ ⁃ ⁃ ⁃ ⁃ 11:30 Single Table Byte Addressability ⁃ ⁃ ⁃ ⁃ ⁃ ⁃ ⁃ ⁃ 16:00 Single Table Page addressability ⁃ ⁃ ⁃ ⁃ ⁃ 19:00 Multi-level Paging (Radix tree) ⁃ ⁃ 31:00 Huge Tables ⁃ ⁃ 33:00 TLB ⁃ ⁃ Summary

6. 

   31 Oct 2025 · 24 min

   Amazon US-EAST-1 Outage in Details

   On October 19 2025 AWS experienced an outage that lasted over a day, 10 days later we finally got the root cause analysis and we know exactly what caused the DNS to fail0:00 Summary 5:30 How did Dynamo lost its DNS?13:41 EC2 Errors 16:16 Network Load Balancer ErrorsRCA here https://aws.amazon.com/message/101925/

7. 

   17 Oct 2025 · 26 min

   Graceful shutdown in HTTP

   There are cases where the backend may need to close the connection to prevent unexpected situations, prevent bad actors or simply just free up resources. Closing a connection gracefully allows clients and backends to clean up and finish any pending requests. In this episode of the backend engineering show I discuss graceful connections in both HTTP/1.1 via the connection header and HTTP/2 via the GOAWAY frame. 0:00 Intro 4:58 Why shutdown connection? 6:46 HTTP/1.1 Graceful shutdown 12:26 Cost of HTTP/2 17:40 HTTP/2 GoAWAY frame 23:40 Summary Links…

8. 

   3 Oct 2025 · 41 min

   Postgres 18 gets Async IO

   Postgres 18 has been released with many exciting features such as UUIDv7, Over explain module, composite index skip scans, and the most anticipated asynchronous IO with worker and io_uring mode which I uncover in this show. Hope you enjoy it 0:00 Intro 1:30 Synchronous vs Asynchronous calls 3:00 Synchronous IO 6:30 Asynchronous IO 10:00 Postgres 17 synchronous io 17:20 The challenge of Async IO in Postgres 18 20:00 io_method worker23:00 io_method io_uring 29:30 io_method sync 31:08 Async IO isn’t done! 3 1:30 Support for backend writers 32:36 Improve worker io_method 33:00 direct io support…

9. 

   13 Jun 2025 · 23 min

   Kernel level TLS

   Fundamentals of Operating Systems Course https://oscourse.winktls is brilliant.TLS encryption/decryption often happens in userland. While TCP lives in the kernel. With ktls, userland can hand the keys to the kernel and the kernel does crypto. When calling write, the kernel encrypts the packet and send it to the NIC.When calling read, the kernel decrypts the packet and handed it to the userspace. This mode still taxes the host’s CPU of course, so there is another mode where the kernel offloads the crypto to the NIC device! Host CPU becomes free. Incoming packets to the NIC are decrypted in…

10. 

    9 May 2025 · 10 min

    The beauty of the CPU

    If you are bored of contemporary topics of AI and need a breather, I invite you to join me to explore a mundane, fundamental and earthy topic. The CPU. A reading of my substack article https://hnasr.substack.com/p/the-beauty-of-the-cpu