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How Linux Namespaces and cgroups Work: Isolation, Resource Limits, and Why a Container Is Not a Virtual Machine

A process that calls unshare(CLONE_NEWPID) and then fork does not get a private machine. It gets a private view of process IDs. The child se...

Sarthak Bystander 13 Oct, 2026

Latest Posts

How Linux Namespaces and cgroups Work: Isolation, Resource Limits, and Why a Container Is Not a Virtual Machine

A process that calls unshare(CLONE_NEWPID) and then fork does not get a private machine. It gets a private view of process IDs. The child se...

Sarthak Bystander 13 Oct, 2026

How DMA and the IOMMU Work: Addresses, Translation, and Why Devices Cannot Touch Arbitrary Host Memory

A network interface that just received a frame does not interrupt the CPU so the processor can copy the payload. The device writes the frame...

Sarthak Bystander 12 Oct, 2026

How BGP Works: AS Paths, Path Attributes, and Why the Internet Is Not Shortest-Path

A packet from a laptop in Mumbai to a server in Frankfurt does not ask the Internet for the shortest path. It follows a route that some netw...

Sarthak Bystander 9 Oct, 2026

How Memory Ordering Works: Store Buffers, Barriers, and Why x86 Is Not Sequentially Consistent

Two threads can each write a flag and then read the other thread's flag, and both reads can return the old value. Nothing in the source ...

Sarthak Bystander 8 Oct, 2026

How UTF-8 and Unicode Work: Code Points, Bytes, and Why Length Is Three Numbers

A string that looks like one character can be one byte, two bytes, or several code points that a font draws as a single glyph. len in one l...

Sarthak Bystander 7 Oct, 2026

How IEEE 754 Floating Point Works: Formats, Rounding, and Why 0.1 Is Not Exact

A statement like 0.1 + 0.2 == 0.3 fails in Python, JavaScript, Java, Go, and C for the same reason. None of those languages stored the deci...

Sarthak Bystander 6 Oct, 2026

How the Linux Buddy and SLUB Allocators Work: Orders, Partial Slabs, and Why malloc Is Not a Page Fault

A driver that calls kmalloc(256, GFP_ATOMIC) from an interrupt handler and a process that calls malloc(256) are not talking to the same al...

Sarthak Bystander 5 Oct, 2026

How NAND Flash and the FTL Work: Pages, Erase Blocks, and Why a Small Write Rewrites a Block

A database that updates a 4 KiB page does not update a 4 KiB cell on the SSD. The host sends a logical block address. The drive's flash ...

Sarthak Bystander 4 Oct, 2026

How Dynamic Linking Works: PLT, GOT, and Why the First Call Is Indirect

A call to puts in a normal C binary is not a direct jump to libc. The machine code in the executable names a procedure-linkage-table stub. ...

Sarthak Bystander 3 Oct, 2026

How fork and Copy-on-Write Work: Page Tables, Shared Pages, and Why the Child Is Not Free

A prefork server that looked cheap in RSS before the first request can double its memory after workers start handling traffic. fork did not...

Sarthak Bystander 2 Oct, 2026

How the Linux VFS Works: Inodes, Dentries, and Why Paths Are Not Files

An open("/var/log/app.log", O_RDONLY) does not hand the kernel a file. It hands the kernel a string. The Virtual File System (VFS...

Sarthak Bystander 1 Oct, 2026