Skip to content

lscpu Command Cheat Sheet

lscpu gathers CPU architecture information from sysfs and /proc/cpuinfo. It displays the number of threads, cores, sockets, and NUMA nodes, as well as CPU caches and family/model.

Synopsis

lscpu [OPTIONS]

Basic Output

lscpu
Key Fields Explained: - Architecture: x86_64 (64-bit) or aarch64 (ARM). - CPU(s): Total logical CPUs (Threads). - Thread(s) per core: Hyper-threading (usually 1 or 2). - Core(s) per socket: Physical cores per CPU package. - Socket(s): Number of physical CPU chips. - Virtualization: VT-x or AMD-V (Important for VMs). - Hypervisor vendor: If you are inside a VM (e.g., KVM, VMware).

Specific Information

Extended Readable Output (-e)

Shows a table of all online CPUs with their assignments.

lscpu -e
Columns: - CPU: Logical CPU ID. - CORE: Physical Core ID. - SOCKET: Physical Socket ID. - NODE: NUMA Node ID. - CACHE: L1/L2/L3 cache sharing group.

Parseable Output (-p)

CSV-friendly format, easier for scripts.

lscpu -p
Output: # CPU,Core,Socket,Node,,L1d,L1i,L2,L3 0,0,0,0,,0,0,0,0

JSON Output (-J)

Modern JSON format for automation.

lscpu -J

Filtering

Show Online/Offline CPUs

In hot-pluggable systems, some CPUs might be offline.

lscpu --online    # Default
lscpu --offline

Show Caches

Displays sizes of L1, L2, L3 caches.

lscpu | grep -i cache
Typical hierarchy: - L1d/L1i: Fastest, per core (Data/Instruction). - L2: Fast, per core. - L3: Large, shared across all cores in a socket.

Practical Examples

Calculate Physical Cores

Total logical CPUs is simpler to find, but for licensing or performance, you often need physical cores.

lscpu | grep "Core(s) per socket"
lscpu | grep "Socket(s)"
(Multiply them = Total Physical Cores).

Check Virtualization Support

Can I run KVM/VirtualBox?

lscpu | grep Virtualization
# Output: Virtualization: VT-x

Notes

  • Byte Order: Shows Little Endian (Intel/AMD) or Big Endian.
  • Flags: The "Flags" section lists instruction sets supported (e.g., avx, sse, aes).
  • Bogomips: A meaningless metric for speed, used only for kernel calibration.