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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

Latest Posts

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

How sendfile and splice Work: Pipe Buffers, Page References, and Why Zero-Copy Is Not Zero Work

A static file server that uses read() into a user buffer and write() onto a socket copies every byte twice through the CPU: page cache to ...

Sarthak Bystander 30 Sept, 2026

How Linux Interrupts Work: Hardware IRQs, Softirqs, and Why Threaded Handlers Exist

A NIC that just received a frame cannot wait for the current process to finish a syscall. The device raises a hardware interrupt. The CPU st...

Sarthak Bystander 29 Sept, 2026

How Linux Signals Work: Pending Masks, Delivery on Return to Userspace, and Why They Are Not Interrupts

A process that spends all its time in a tight userspace loop never notices SIGTERM until the kernel has a chance to put that process back on...

Sarthak Bystander 28 Sept, 2026

How the Linux Page Cache Works: Radix Trees, Writeback, and Why read() Hits DRAM

A process asks for a few bytes from a file. The kernel may return them without asking the storage device for anything at all—not because the...

Sarthak Bystander 27 Sept, 2026

How Futexes Work: Userspace Fast Path, Wait Queues, and Why Mutexes Avoid Syscalls

A mutex that takes a system call on every lock and unlock would dominate a hot critical section. The uncontended case is a few atomic instru...

Sarthak Bystander 25 Sept, 2026

How epoll Works: Readiness, Level vs Edge Trigger, and Why select Doesn't Scale

A process that accepts ten thousand TCP connections cannot afford to ask the kernel about each socket in turn. select(2) and poll(2) copy ...

Sarthak Bystander 24 Sept, 2026

How RCU Works: Grace Periods, Quiescent States, and Why Readers Skip Locks

A shared linked list in the kernel can be walked by thousands of cores at once. A writer still has to insert or delete a node. If every walk...

Sarthak Bystander 23 Sept, 2026

How Linux CFS Works: vruntime, Red-Black Trees, and Why Fairness Is Approximate

A CPU core runs one thread at a time. Everything else that looks concurrent is a lie the operating system maintains by switching. The policy...

Sarthak Bystander 22 Sept, 2026