Why CPU Time ≠ Wall Clock Time! - Computerphile

Why watch

Matt Godbolt explains the fundamental difference between CPU time (the processor cycles actually consumed by a program) and wall clock time (the total elapsed time from start to finish). Covers how operating systems track and report these metrics, why they differ (due to scheduling, I/O waits, and other processes), and practical implications for measuring program performance. Ideal for programmers seeking to accurately benchmark and profile their code.