In the Linux operating system, memory is a key resource used to store data for running programs and the operating system itself. If the system's memory usage is too high, it may result in poor performance, application crashes, or system crashes. Therefore, it is very important to know how to check if Linux memory usage is exhausted. Below are some common methods that can help you check if your Linux memory usage is exhausted.
1. Use the free command
The free command is a tool for viewing system memory usage. The free command can be run with:
free -h
This command will display the memory usage of the system, including information such as used memory, available memory, and cached memory. You can focus on the following fields:
- total: Indicates the total memory capacity of the system.
- used: Indicates the amount of memory used, including memory used by applications and the kernel.
- free: Indicates the amount of memory currently free in the system.
- cached: Indicates the amount of memory cached by the system, including the file system and data cached by the kernel.
If the used field is close to or equal to the total field, then the system may have run out of memory.
2. Use the top command
The top command is a tool for monitoring system resource usage in real time, including memory. The top command can be run with:
top
In the top command interface, you can see the current memory usage of the system. Pay attention to the following fields:
- %MEM: Indicates the proportion of physical memory used by the process.
- VIRT: Indicates the size of virtual memory used by the process.
- RES: Indicates the actual physical memory size used by the process.
You can press Shift + M to sort the processes by memory usage to find out which processes take up more memory.
3. Using the /proc/meminfo file
The Linux kernel saves the memory information of the system in the /proc/meminfo file, which can be read to obtain the memory usage of the system. The contents of the /proc/meminfo file can be viewed with the following command:
cat /proc/meminfo
This file contains various memory information of the system, such as total memory capacity, free memory, cache memory, etc. You can focus on the following fields:
- MemTotal: Indicates the total memory capacity of the system.
- MemFree: Indicates the amount of free memory currently in the system.
- Cached: Indicates the amount of memory cached by the system, including the file system and data cached by the kernel.
If the value of the MemFree field is low and the value of the Cached field is high, it may indicate that the system's memory is being used by the cache rather than real free memory. At this time, you can consider freeing memory by clearing the cache.
4. Use the htop command
htop is a more powerful and interactive top-like tool that helps you monitor system resource usage, including memory, more intuitively. You can install and run htop with the following command:
sudo apt-get install htop
htop
In the htop command interface, you can view the memory usage of each process more clearly through colors and graphics, including real-time memory usage charts.
5. Use the ps command
The ps command is a tool for viewing system process information. You can view the memory usage of each process by matching parameters. The ps command can be run with:
ps aux
In the output results, you can pay attention to the following fields:
- %MEM: Indicates the proportion of physical memory used by the process.
- RSS: Indicates the actual physical memory size used by the process.
The output can be sorted, filtered, or formatted as needed to find processes that take up more memory.
in conclusion
The above are several commonly used methods that can help you check whether the memory usage of your Linux system is exhausted. By using these tools and commands, you can monitor the memory usage of the system in real time, discover the situation of memory exhaustion in time, and take corresponding measures, such as clearing the cache, optimizing the process, increasing memory, etc., to ensure the stability and performance of the system . In practice, choose the appropriate method based on your needs and system environment, and follow best practices for system administrators.