The Ninety-Ninth Percentile: Operating System Internals

From Atlas, CTSS, Multics and Unix to Linux; system calls and Meltdown mitigations; scheduling from multilevel feedback queues to CFS, EEVDF and schedext; page tables, TLBs, page faults and copy on write; transparent huge pages and compaction stalls; epoll and iouring; eBPF, XDP and Cilium; DPDK, SPDK, RDMA and Seastar; fsyncgate and direct I/O; namespaces, cgroups and CPU throttling; hypervisors and nested paging; file systems, blk-mq, NVMe and flash translation layers; allocators and NUMA; the USE method, flame graphs and coordinated omission. Cross-references: ep163 (caches), ep166, ep174 (cloud outages), ep180 (write-ahead logs). Chapters 00:00:00 Cold open: the ninety-ninth percentile 00:02:22 What an operating system is for 00:06:00 Scheduling: who runs next 00:11:18 Virtual memory: the great illusion 00:14:17 Huge pages and the culprit 00:18:37 Input and output: from blocking calls to iouring 00:22:51 eBPF: programs inside the kernel 00:26:50 Kernel bypass: when the kernel is too slow 00:30:58 The page cache and the fsync problem 00:34:34 Containers are just processes 00:38:59 Virtual machines and the hypervisor 00:42:24 Measuring the machine 00:45:02 File systems and the storage stack 00:49:17 Allocators, NUMA and the cost of sharing 00:51:33 Interrupts, timers and the noisy neighbour inside the machine 00:54:02 The kernel as a security boundary 00:58:43 Dawn: a flat line Created by Sankalp Thakur. A Transient Labs production. Website: https://transientlabs.ai GitHub: https://github.com/sankalpsthakur X / Twitter: https://x.com/sankalpsthakur LinkedIn:   / sankalpthakur   Hugging Face: https://huggingface.co/sankalpsthakur Scripts generated with Claude Opus. Synthetic narration generated with Kokoro. Reviewed, listened to, and approved by Sankalp Thakur.