lscpu

Overview

The lscpu command displays detailed information about the CPU architecture, including processor type, cores, threads, cache sizes, and various CPU features.

Syntax

lscpu [options]

Common Options

Option Description
-a Include offline CPUs
-b Online CPUs only
-c Compatible format
-e Extended readable format
-p Parsable format
-s directory Use specific sysfs directory
-x Include hex and binary flags
-y Show physical IDs

Key Information Displayed

Field Description
Architecture CPU architecture (x86_64, ARM, etc.)
CPU op-mode(s) 32-bit, 64-bit
Byte Order Little Endian, Big Endian
CPU(s) Total number of logical CPUs
Thread(s) per core Hyperthreading info
Core(s) per socket Physical cores per CPU
Socket(s) Number of CPU sockets
Model name CPU brand and model
CPU MHz Current frequency
CPU max MHz Maximum frequency
CPU min MHz Minimum frequency
Cache sizes L1, L2, L3 cache information

Key Use Cases

  1. System inventory
  2. Performance analysis
  3. Virtualization planning
  4. Hardware compatibility checks
  5. System monitoring setup

Examples with Explanations

Example 1: Basic CPU Information

lscpu

Shows complete CPU information in human-readable format

Example 2: Parsable Format

lscpu -p

Outputs CPU information in comma-separated format for scripting

Example 3: Extended Format

lscpu -e

Shows extended information including NUMA topology

Understanding CPU Topology

Key relationships: - Socket: Physical CPU package - Core: Physical processing unit - Thread: Logical processing unit (with hyperthreading) - NUMA Node: Memory locality group

Calculation:

Total CPUs = Sockets × Cores per socket × Threads per core

Common Usage Patterns

  1. Check CPU count:

    lscpu | grep "CPU(s):"

  2. Get CPU model:

    lscpu | grep "Model name"

  3. Check virtualization support:

    lscpu | grep Virtualization

Performance Analysis

Information useful for performance: - Cache sizes (L1, L2, L3) - CPU frequency ranges - Thread/core ratios - NUMA topology - CPU flags and features

Scripting Examples

  1. Extract CPU count:

    CPU_COUNT=$(lscpu | grep "^CPU(s):" | awk '{print $2}')

  2. Check architecture:

    ARCH=$(lscpu | grep "Architecture:" | awk '{print $2}')

  3. Get CPU model:

    MODEL=$(lscpu | grep "Model name:" | cut -d':' -f2 | xargs)

Parsable Output Format

Using -p option provides CSV-like output:

# CPU,Core,Socket,Node,,L1d,L1i,L2,L3
0,0,0,0,,32K,32K,256K,8192K
1,1,0,0,,32K,32K,256K,8192K

Additional Resources

Best Practices

  1. Use parsable format for scripts
  2. Check virtualization capabilities
  3. Monitor CPU frequency scaling
  4. Understand NUMA topology for optimization
  5. Verify CPU features for software requirements

Virtualization Information

CPU virtualization features: - VT-x/AMD-V: Hardware virtualization - VT-d/AMD-Vi: I/O virtualization - EPT/NPT: Extended/Nested page tables

Check support:

lscpu | grep -E "(vmx|svm)"

NUMA Topology

For multi-socket systems:

lscpu | grep NUMA

Shows: - NUMA node count - CPU-to-node mapping - Memory locality information

CPU Flags and Features

Important flags: - sse, sse2, sse3: SIMD instructions - aes: AES encryption support - avx, avx2: Advanced vector extensions - rdrand: Hardware random number generator

Frequency Information

Modern CPUs show: - Base frequency - Maximum turbo frequency - Current frequency - Scaling governor information

Integration Examples

  1. System monitoring:

    echo "CPU: $(lscpu | grep 'Model name' | cut -d':' -f2 | xargs)"

  2. Performance tuning:

    CORES=$(lscpu | grep "Core(s) per socket" | awk '{print $4}')
make -j$CORES

  3. Capacity planning:

    lscpu -p | grep -v "^#" | wc -l

Troubleshooting

  1. Missing CPU information
  2. Incorrect core counts
  3. Frequency scaling issues
  4. Virtualization detection problems
  5. NUMA topology confusion

Output Filtering

  1. Get specific information:

    lscpu | grep -i cache

  2. Extract numeric values:

    lscpu | grep "CPU(s):" | grep -o '[0-9]*'

  3. Format for reports:

    lscpu | grep -E "(Architecture|CPU\(s\)|Model name)"