CPU (Central Processing Unit)

Slug

cpu-central-processing-unit

Short definition

The CPU is the primary component of a computer that executes instructions, performs calculations, and controls system operations.

Full definition (rich content)

What is a CPU?

The Central Processing Unit (CPU) is the main processing component of a computer or server. It executes program instructions, processes data, and coordinates the activities of all other hardware components.

The CPU is often referred to as the "brain" of the system.

Why the CPU matters

The CPU is critical because it:

• Executes operating system and application code
• Performs arithmetic and logical operations
• Manages task scheduling and process execution
• Impacts overall system performance and responsiveness
• Determines how workloads scale and behave

CPU performance directly affects user experience and system capacity.

Core CPU components

A modern CPU is composed of:

• Cores -- independent processing units within the CPU
• Threads -- execution paths per core (via SMT/Hyper-Threading)
• Clock speed -- number of cycles per second (GHz)
• Cache -- fast internal memory (L1, L2, L3)
• Instruction set -- supported operations (x86, ARM, etc.)

These components work together to process instructions efficiently.

CPU cores and threads

• Single-core CPU -- one execution unit
• Multi-core CPU -- multiple cores for parallel processing
• Simultaneous multithreading (SMT) -- multiple threads per core

More cores and threads generally improve multitasking and parallel workloads.

CPU cache

CPU cache is high-speed memory used to store frequently accessed data:

• L1 cache -- fastest, smallest
• L2 cache -- balanced speed and size
• L3 cache -- shared across cores

Efficient cache usage significantly improves performance.

CPU vs GPU

Aspect	CPU	GPU
Purpose	General-purpose processing	Parallel computation
Cores	Few, powerful	Many, lightweight
Workloads	OS, apps, logic	Graphics, AI, compute
Flexibility	High	Specialized

CPUs handle control and logic; GPUs excel at massively parallel tasks.

CPU in servers and virtualization

In enterprise environments, CPUs:

• Run multiple virtual machines or containers
• Share cores across workloads
• Affect consolidation ratios
• Influence licensing and cost models

CPU allocation is a key factor in virtualization performance.

CPU in cloud environments

In cloud platforms:

• CPUs are abstracted as virtual CPUs (vCPUs)
• Performance depends on instance type and architecture
• CPU selection impacts cost and scalability
• Burstable and dedicated CPU models exist

Understanding CPU characteristics is essential for right-sizing.

CPU performance factors

CPU performance depends on:

• Clock speed and core count
• Cache size and efficiency
• Instruction set optimizations
• Thermal limits and power consumption
• Workload characteristics (single-threaded vs parallel)

Raw GHz alone does not define performance.

Common misconceptions

• "Higher clock speed always means better performance"
• "More cores always improve performance"
• "CPU performance is the only system bottleneck"
• "All CPUs behave the same in virtual machines"