vmstat命令用於監(jiān)控系統(tǒng)虛擬內(nèi)存、CPU使用率、進(jìn)程和I/O活動(dòng)。其核心用途包括：1. 查看運(yùn)行或等待資源的進(jìn)程數(shù)，通過r（等待CPU時(shí)間的進(jìn)程）和b（不可中斷睡眠的進(jìn)程）列判斷系統(tǒng)負(fù)載；2. 監(jiān)控內(nèi)存使用情況，swpd（交換到磁盤的內(nèi)存）、free（空閒內(nèi)存）、buff/cache（內(nèi)核緩沖和緩存）可反映RAM是否充足；3. 觀察CPU使用率，us（用戶進(jìn)程）、sy（系統(tǒng)進(jìn)程）、id（空閒時(shí)間）、wa（I/O等待時(shí)間）幫助識(shí)別性能瓶頸；4. 跟蹤分頁(yè)和交換行為，si（從交換區(qū)讀?。┖蛃o（寫入交換區(qū)的內(nèi)存）顯示內(nèi)存壓力。頻繁交換可能導(dǎo)致性能下降，需考慮增加RAM或優(yōu)化程序內(nèi)存使用。

The vmstat command is used to monitor and report information about your system's virtual memory, CPU usage, processes, and I/O activity. It gives you a snapshot of how well your system is performing, especially when troubleshooting performance issues or checking resource utilization.

Checking System Processes

One of the main uses of vmstat is to show how many processes are currently running or waiting for resources.
When you run vmstat , the first line of output shows averages since the last reboot, and subsequent lines (if you specify an interval) show real-time data.

Key columns here include:

• r : Number of processes waiting for CPU time
• b : Number of processes in uninterruptible sleep (usually waiting for disk or network I/O)

If you see high values in either of these columns over time, it could mean your system is overloaded or waiting on slow hardware.

Monitoring Memory Usage

vmstat also provides details about free and used memory, including swap space.
It breaks down memory into categories like:

• swpd : How much memory has been swapped out to disk
• free : Amount of idle memory
• buff/cache : Memory used by kernel buffers and cache

High swap usage (swpd) might indicate that your system is low on RAM and offloading memory to disk, which can significantly slow things down.

Watching CPU Activity

By using vmstat with a delay and count — like vmstat 2 5 — you can observe CPU usage over time.
Each line after the first shows CPU activity broken down into:

• us : User processes
• sy : System (kernel) processes
• id : Idle time
• wa : Time spent waiting for I/O

If you notice high wa time consistently, your system might be bottlenecked by disk or network operations.

Tracking Paging and Swapping

Another key feature of vmstat is showing memory paging and swapping behavior through columns like:

• si : Memory read from swap (swap in)
• so : Memory written to swap (swap out)

Frequent swapping can hurt performance, so watching these numbers helps identify if your system needs more RAM or if some processes are using too much memory.

基本上就這些。
You don't need to memorize every column, but knowing what each one roughly represents makes vmstat a powerful tool for quick system checks.

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