Command
cat /proc/cpuinfo
processor : 0
BogoMIPS : 48.00
Features : fp asimd evtstrm crc32 atomics fphp asimdhp cpuid asimdrdm lrcpc dcpop asimddp
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x2
CPU part : 0xd05
CPU revision : 0
processor : 1
BogoMIPS : 48.00
Features : fp asimd evtstrm crc32 atomics fphp asimdhp cpuid asimdrdm lrcpc dcpop asimddp
CPU implementer : 0x41
CPU architecture: 8
CPU variant : 0x2
CPU part : 0xd05
CPU revision : 0
<span>processor</span>: Indicates the CPU core number, starting from 0<span>BogoMIPS</span>: Abbreviation for “Bogus Million Instructions Per Second”, not a real performance metric.- This is a rough estimate used by Linux at startup to gauge CPU latency (mainly for timing).
- A higher value indicates that the CPU can execute empty instruction loops faster, but it cannot be used to compare performance.
<span>Features</span>: The hardware features (instruction set extensions) supported by this CPU- fp: Floating-point operations
- asimd: ARM SIMD (similar to NEON, vector instructions)
- crc32: CRC32 instruction
- atomics: Support for atomic operations
- fphp, asimdhp: Half-precision floating-point support
- cpuid: CPUID instruction support (can query features)
- asimddp, lrcpc, dcpop etc.: ARMv8.2 or higher instruction extensions
<span>CPU implementer</span>: Vendor identifier- 0x41 indicates ARM Holdings (i.e., official ARM cores, not customized cores from Qualcomm, Apple, etc.)
<span>CPU architecture</span>: Indicates the ARM architecture version- 8 is ARMv8 (64-bit architecture, supports AArch64 mode)
<span>CPU variant</span>: Indicates different variants of the same CPU model (e.g., different process versions)<span>CPU part</span>: Specific CPU model- 0xd05 is Cortex-A55, a high-performance, low-power ARMv8.2-A architecture core, commonly found in embedded or mobile chips.
<span>CPU revision</span>: Indicates the revision version of this core
CPU Usage
Command
top
top - 00:25:34 up 25 min, 1 user, load average: 0.00, 0.00, 0.02
Tasks: 108 total, 1 running, 107 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.3 us, 0.3 sy, 0.0 ni, 99.2 id, 0.0 wa, 0.2 hi, 0.0 si, 0.0 st
MiB Mem : 855.4 total, 267.6 free, 344.3 used, 243.5 buff/cache
MiB Swap: 0.0 total, 0.0 free, 0.0 used. 435.2 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
384 root 20 0 365092 72716 36888 S 0.7 8.3 0:11.84 mxapp2
407 root 20 0 1432752 80108 35220 S 0.7 9.1 0:07.74 dockerd
System Load
top - 00:25:34 up 25 min, 1 user, load average: 0.00, 0.00, 0.02
- 00:25:34: Current time
- up 25 min: The system has been running for 25 minutes
- 1 user: Current number of logged-in users
- load average: 0.00, 0.00, 0.02
<span>1 minute</span>,<span>5 minutes</span>,<span>15 minutes</span>average load (number of processes in the run queue per core)- A value close to 0 indicates that the system is idle. This machine is very idle.
Task Status
Tasks: 108 total, 1 running, 107 sleeping, 0 stopped, 0 zombie
- 108 total: A total of 108 processes
- 1 running: Currently, 1 process is running (using CPU)
- 107 sleeping: The rest are waiting (most system or daemon processes are in this state)
- 0 zombie: No zombie processes (processes that have ended but have not yet been collected)
CPU Usage
%Cpu(s): 0.3 us, 0.3 sy, 0.0 ni, 99.2 id, 0.0 wa, 0.2 hi, 0.0 si, 0.0 st
<span>us</span>: User space usage 0.3% (running normal programs)<span>sy</span>: Kernel space usage 0.3% (running system calls)<span>ni</span>: Processes with nice values occupy 0.0%<span>id</span>: CPU idle time 99.2%<span>wa</span>: Waiting for I/O (disk/network) time 0.0%<span>hi</span>: Hardware interrupt time 0.2%<span>si</span>: Software interrupt time 0.0%<span>st</span>: Steal Time time stolen by the virtual machine 0.0%
Overall, the CPU is almost idle, and the system is under very little pressure.
RAM Memory Usage
MiB Mem : 855.4 total, 267.6 free, 344.3 used, 243.5 buff/cache
MiB Swap: 0.0 total, 0.0 free, 0.0 used. 435.2 avail Mem
Physical Memory
<span>total</span>: Total system memory 855.4 MiB.<span>free</span>: Free memory 267.6 MiB.<span>used</span>: Memory used by programs.<span>buff/cache</span>: Memory used by the system for cache or buffers, which can be reclaimed.
Swap Space
<span>total</span>: Swap is not enabled<span>avail Mem</span>: Approximately 435.2 MiB available (free + reclaimable)
Process List
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
384 root 20 0 365092 72716 36888 S 0.7 8.3 0:11.84 mxapp2
407 root 20 0 1432752 80108 35220 S 0.7 9.1 0:07.74 dockerd
...
| Field | Meaning |
|---|---|
| PID | Process ID |
| USER | Owner user (root) |
| PR | Priority |
| NI | Nice value (compensation for scheduling priority) |
| VIRT | Total virtual memory (including mmap, shared libraries, etc.) |
| RES | Actual physical memory usage (resident memory) |
| SHR | Shared memory |
| S | Status (S=Sleeping) |
| %CPU | CPU usage rate |
| %MEM | Memory usage rate |
| TIME+ | Total running time |
| COMMAND | Process name |
Example Explanation
- mxapp2 (PID 384): uses 8.3% memory, 0.7% CPU, running time 11.84 seconds.
- dockerd (PID 407): is the Docker daemon, using 9.1% memory, CPU usage is also very low.
CPU Temperature
Command
cat /sys/class/thermal/thermal_zone0/temp
48500
- This path is the thermal sensor interface of the Linux kernel, used to read the current temperature of the CPU or SoC (may vary slightly depending on the platform).
<span>thermal_zone0</span>: Indicates the first thermal sensor (usually the CPU).<span>temp</span>: Indicates the current temperature, in milli-degrees Celsius (1/1000 degrees Celsius).
CPU Stress Testing
yes Command
<span>yes</span> is a very simple but useful command-line tool for stress testing, which continuously outputs a string (default is y) until forcibly stopped. Because yes continuously performs output operations (string + newline), it will continuously occupy the CPU, making it very suitable for simple CPU usage testing.
Test Command
yes > /dev/null &
- Each yes instance fully occupies 1 CPU core; run as many instances as there are cores.
- Using & indicates running in the background.
- To terminate the test:
<span>killall yes</span>
View Metrics
| Metric Category | Parameter Name | Method of Acquisition | Description |
|---|---|---|---|
| 🔧 CPU Usage | Per-core usage rate | <span>top</span>, <span>htop</span> |
The goal is for each core usage rate to approach 100% |
| 🔁 Load Average | 1/5/15 minute load | <span>cat /proc/loadavg</span> |
<span>loadavg</span> ≈ number of CPU cores indicates the load is just right |
| 🌡 Temperature | CPU temperature | <span>cat /sys/class/thermal/thermal_zone*/temp</span> |
Check if it exceeds the temperature limit (e.g., 85℃) |
| 🕓 Response Latency | System response speed | Estimate command response time using <span>time ls</span>, <span>ping localhost</span> |
|
| 📈 Context Switches | <span>ctxt</span> |
<span>cat /proc/stat</span> before and after comparison |
Check if context switches spike under high load |
| ⏱ Interrupts | <span>intr</span> |
<span>cat /proc/stat</span> |
Frequent interrupts may indicate system overload or hardware issues |
| 💾 Free Memory | <span>free -m</span>, <span>cat /proc/meminfo</span> |
Ensure memory is not being abnormally occupied | |
| 🚫 Errors/Warnings | <span>dmesg</span> |
Check for warnings about CPU temperature, frequency limits, etc. |
High-Precision π Calculation
time echo "scale=5000; 4*a(1)" | bc -l -q
- time: Tests the execution time of the command
- scale=5000: Calculates π to 5000 decimal places.
- a(1) is the arctangent function, resulting in π/4.
- 4*a(1) approximates π.
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