如何在Linux上使用vmstat命令

╰+哭是因爲堅強的太久メ 2021-07-26 19:35 541阅读 0赞

![Terminal prompt on a Linux desktop][][Fatmawati Achmad Zaenuri/Shutterstock.com][Fatmawati Achmad Zaenuri_Shutterstock.com] [Fatmawati Achmad Zaenuri / Shutterstock.com][Fatmawati Achmad Zaenuri_Shutterstock.com]

Your Linux or macOS computer is using virtual memory. Discover how it’s affecting your system’s use of physical memory, CPU, and hard disk resources.

您的Linux或macOS计算机正在使用虚拟内存。 了解它如何影响系统对物理内存，CPU和硬盘资源的使用。

## 什么是虚拟内存？ **(**What Is Virtual Memory?**)** ##

Your computer is fitted with a finite amount of physical memory called [random access memory][] (RAM). This RAM needs to be managed by the kernel and shared between the operating system and whatever applications happen to be running. If these combined demands are asking for more memory than is physically installed in your computer, what can the kernel do?

您的计算机装有有限数量的物理内存，称为[随机存取内存][random access memory] (RAM)。 该RAM需要由内核管理，并在操作系统和任何正在运行的应用程序之间共享。 如果这些综合需求要求的内存比计算机中实际安装的内存更多，那么内核可以做什么？

Linux and [Unix-like][] operating systems such as macOS can use space on your hard disk to help them manage memory demands. A reserved area of hard drive space called “swap space” can be used as though it were an extension of RAM. This is virtual memory.

诸如macOS之[类的][Unix-like] Linux和[Unix之类的][Unix-like]操作系统可以使用硬盘上的空间来帮助他们管理内存需求。 可以将硬盘驱动器空间的保留区域称为“交换空间”，就像它是RAM的扩展一样。 这是虚拟内存。

The Linux kernel can write the contents of a block of memory into swap space, and free up that region of RAM for use by another process. The swapped out—also called “paged” out—memory can be retrieved from the swap space and restored to RAM when it is required.

Linux内核可以将一块内存的内容写入交换空间，并释放该RAM区供其他进程使用。 交换出的内存(也称为“分页”输出)可以从交换空间中检索出来，并在需要时恢复到RAM中。

Of course, the speed of access for paged out memory is slower than that of memory held in RAM. And that’s not the only trade-off. Whilst virtual memory does provide a way for Linux to manage its memory demands, using virtual memory places increased burdens elsewhere on the computer.

当然，分页内存的访问速度比RAM中保存的内存的访问速度慢。 这不是唯一的权衡。 尽管虚拟内存确实为Linux提供了一种管理内存需求的方法，但是使用虚拟内存给计算机的其他地方增加了负担。

Your hard drive must perform more reads and writes. The kernel—and hence, the CPU—must do more work as it swaps memory out, swaps memory in, and keeps all the plates spinning to satisfy the memory needs of the different processes.

您的硬盘驱动器必须执行更多读取和写入操作。 内核-因此，CPU-必须进行更多工作，因为它要交换内存，交换内存并保持所有板块旋转以满足不同进程的内存需求。

Linux provides a way for you to monitor all of this activity in the shape of the `vmstat` command, which reports on [virtual memory statistics][].

Linux提供了一种以`vmstat`命令的形式监视所有这些活动的方法，该命令报告[虚拟内存统计信息][virtual memory statistics] 。

## vmstat命令 **(**The vmstat Command**)** ##

If you type `vmstat` as a command with no parameters, it will show you a set of values. These values are the *averages* for each of the statistics since your computer was last rebooted. These figures are not a snapshot of the values “right now.”

如果键入`vmstat`作为不带参数的命令，它将显示一组值。 这些值是自上次重新启动计算机以来每个统计信息的*平均值* 。 这些数字不是“立即”值的快照。

vmstat

![vmstat in a terminal window][]

A short table of values is displayed.

将显示一个简短的值表。

![vmstat output in a terminal window][]

There are columns headed Procs, Memory, Swap, IO, System, and CPU. The final column (most right-hand column) contains the data relating to the CPU.

有标题为Procs，Memory，Swap，IO，System和CPU的列。 最后一栏(最右边的一栏)包含与CPU有关的数据。

![vmstat output right-hand columns in a terminal window][]

Here is a list of the data items in each column.

这是每列中数据项的列表。

Proc

程序

*  *r*: The number of runnable processes. These are processes that have been launched and are either running or are waiting for their next time-sliced burst of CPU cycles.
    
    *r* ：可运行的进程数。 这些是已启动并且正在运行或正在等待下一个时间片突发的CPU周期的进程。
 *  *b*: The number of processes in uninterruptible sleep. The process isn’t sleeping, it is performing a blocking system call, and it cannot be interrupted until it has completed its current action. Typically the process is a device driver waiting for some resource to come free. Any queued interrupts for that process are handled when the process resumes its usual activity.
    
    *b* ：不间断睡眠的进程数。 该进程没有处于Hibernate状态，它正在执行阻塞系统调用，并且在完成当前操作之前不能中断该进程。 通常，该过程是等待某些资源释放的设备驱动程序。 当该进程恢复其正常活动时，将处理该进程的所有排队中断。

Memory

记忆

*  *swpd*: the amount of virtual memory used. In other words, how much memory has been swapped out.,
    
    *swpd* ：使用的虚拟内存量。 换句话说，已换出多少内存。
 *  *free*: the amount of idle (currently unused) memory.
    
    *free* ：空闲(当前未使用)的内存量。
 *  *buff*: the amount of memory used as buffers.
    
    *buff* ：用作缓冲区的内存量。
 *  *cache*: the amount of memory used as cache.
    
    *cache* ：用作缓存的内存量。

Swap

交换

*  *si*: Amount of virtual memory swapped *in* from swap space.
    
    *SI：*从交换空间*中*交换虚拟内存量。
 *  *so*: Amount of virtual memory swapped *out* to swap space.
    
    *因此* ：交换*出*虚拟空间以交换空间。

*  *bi*: Blocks received from a block device. The number of data blocks used to swap virtual memory back into RAM.
    
    *bi* ：从块设备接收的块。 用于将虚拟内存交换回RAM的数据块数。
 *  *bo*: Blocks sent to a block device. The number of data blocks used to swap virtual memory out of RAM and into swap space.
    
    *bo* ：发送到块设备的块。 用于将虚拟内存交换出RAM并交换空间的数据块数。

System

系统

*  *in*: The number of interrupts per second, including the clock.
    
    *in* ：每秒的中断数，包括时钟。
 *  *cs*: The number of context switches per second. A context switch is when the kernel swaps from system mode processing into user mode processing.
    
    *cs* ：每秒上下文切换数。 上下文切换是指内核从系统模式处理切换到用户模式处理时。

CPU

中央处理器

These values are all percentages of the total CPU time.

这些值都是总CPU时间的百分比。

*  *us*: Time spent running non-kernel code. That is, how much time is spent in user time processing and in nice time processing.
    
    *us* ：花费在运行非内核代码上的时间。 即，在用户时间处理和好时光处理中花费了多少时间。
 *  *sy*: Time spent running kernel code.
    
    *sy* ：运行内核代码所花费的时间。
 *  *id*: Time spent idle.
    
    *id* ：空闲时间。
 *  *wa*: Time spent waiting for input or output.
    
    *wa* ：等待输入或输出所花费的时间。
 *  *st*: Time stolen from a virtual machine. This is the time a virtual machine has to wait for the hypervisor to finish servicing other virtual machines before it can come back and attend to this virtual machine.
    
    *st* ：从虚拟机盗取的时间。 这是虚拟机必须等待虚拟机管理程序完成对其他虚拟机的服务之后，才能返回并参与该虚拟机的时间。

## 使用时间间隔 **(**Using a Time Interval**)** ##

We can have `vmstat` provide regular updates to these figures by using a `delay` value. The `delay` value is provided in seconds. To have the statistics updated every five seconds, we’d use the following command:

我们可以让`vmstat`通过使用`delay`值来定期更新这些数据。 `delay`值以秒为单位。 为了使统计信息每五秒钟更新一次，我们将使用以下命令：

vmstat 5

![vmstat 5 in a terminal window][]

Every five seconds `vmstat` will add another line of data to the table. You’ll need to hit Ctrl+C to stop this.

`vmstat`每隔五秒钟将向表中添加另一行数据。 您需要按Ctrl + C才能停止。

![output from vmstat 5 in a terminal window][]

## 使用计数值 **(**Using a Count Value**)** ##

Using too low a `delay` value will put additional strain on your system. If you need to have rapid updates to try to diagnose a problem, it is recommended that you use a `count` value as well as a `delay` value.

使用太低的`delay`值会给您的系统带来额外的压力。 如果需要快速更新以尝试诊断问题，建议您使用`count`数值和`delay`值。

The `count` value tells `vmstat` how many updates to perform before it exits and returns you to the command prompt. If you do not provide a `count` value, `vmstat` will run until it is stopped by Ctrl+C.

`count`数值告诉`vmstat`在退出前将执行多少次更新并使您返回命令提示符。 如果不提供`count`数值，则`vmstat`将一直运行，直到被Ctrl + C停止为止。

To have `vmstat` provide an update every five seconds—but only for four updates—use the following command:

要使`vmstat`每五秒钟提供一次更新(但仅提供四次更新)，请使用以下命令：

vmstat 5 4

![vmstat 5 4 in a terminal window][]

After four updates `vmstat` stops of its own accord.

经过四次更新后， `vmstat`停止。

![output from vmstat 5 4 in a terminal window][]

## 更改单位 **(**Changing the Units**)** ##

You can choose to have the memory and swap statistics displayed in kilobytes or megabytes using the `-S` (unit-character) option. This must be followed by one of `k` , `K` , `m`,  or `M`. These represent:

您可以使用`-S` (单位字符)选项选择以千字节或兆字节为单位显示内存和交换统计信息。 随后必须是`k` ， `K` ， `m`或`M` 。 这些代表：

*  *k*:1000 bytes
    
    *k* ：1000字节
 *  *K*: 1024 bytes
    
    *K* ：1024字节
 *  *m*: 1000000 bytes
    
    *m* ：1000000字节
 *  *M*: 1048576 bytes
    
    *M* ：1048576字节

To have the statistics updated every 10 seconds with the memory and swap statistics displayed in megabytes, use the following command:

要使统计信息每10秒更新一次，以兆字节为单位显示内存和交换统计信息，请使用以下命令：

vmstat 10 -S M

![vmstat 10 -S M ina terminal window][]

The memory and swap statistics are now shown in megabytes. Note that the `-S` option does not affect the IO block statistics. These are always displayed in blocks.

现在以兆字节显示内存和交换统计信息。 请注意， `-S`选项不会影响IO块统计信息。 这些总是以块显示。

![output from vmstat 10 -S M ina terminal window][]

## 活动和非活动内存 **(**Active and Inactive Memory**)** ##

If you use the `-a` (active) option the buff and cache memory columns are replaced by the “inact” and “active” columns. As they would suggest, these show the amount of inactive and active memory.

如果使用`-a` (活动)选项，则buff和缓存内存列将由“ inact”和“ active”列替换。 正如他们所暗示的那样，它们显示了非活动和活动内存的数量。

To see these two columns instead of the buff and cache columns, include the `-a` option, as shown:

要查看这两列而不是buff和cache列，请包括`-a`选项，如下所示：

vmstat 5 -a -S M

![vmstat 5 -a -S M in a terminal window][]

The inact and active columns *are* affected by the -S (unit-character) option.

所述INACT和活性列*由* \-S(单位字符)选项的影响。

![output from vmstat 5 -a -S M in a terminal window][]

## 前叉 **(**Forks**)** ##

The `-f` switch displays the number of forks that have happened since the computer was booted up.

`-f`开关显示自启动计算机以来发生的派生数。

In other words, this shows the number of tasks that have been launched (and, for the bulk of them, closed again) since the system was booted. Every process launched from the command line would increase this figure. Each time a task or process spawns or clones a new task, this figure will increase.

换句话说，这显示了自系统启动以来已启动的任务数量(对于大多数任务而言，再次关闭)。 从命令行启动的每个进程都会增加这个数字。 每次任务或进程产生或克隆新任务时，此数字都会增加。

vmstat -f

![vmstat -f in a terminal window][]

The forks display does not update.

货叉显示不会更新。

## 显示Slabinfo **(**Displaying Slabinfo**)** ##

The kernel has its own memory management to worry about as well as the memory management for the operating system and all of the applications.

内核具有自己需要担心的内存管理以及操作系统和所有应用程序的内存管理。

As you might imagine the kernel is allocating and deallocating memory over and over for the many different types of data object that it must handle. To make this as efficient as possible, it uses a system called slabs. This is a form of caching.

就像您想象的那样，内核会为它必须处理的许多不同类型的数据对象一遍又一遍地分配和释放内存。 为了尽可能提高效率，它使用了一个称为平板的系统。 这是一种缓存形式。

Memory allocated, used, and no longer required for a specific type of kernel data object can be re-used for another data object of the same type without the memory being deallocated and reallocated. Think of slabs as pre-allocated, made to measure, segments of RAM for the kernel’s own needs.

可以为特定类型的内核数据对象分配，使用和不再需要的内存可用于同一类型的另一个数据对象，而无需重新分配和重新分配内存。 可以将slab视为预先分配的，可度量的，可满足内核自身需求的RAM段。

To see the statistics for the slabs, use the `-m` (slabs) option. You will need to use `sudo`, and you will be prompted for your password. As the output can be quite lengthy, we are piping it through `less`.

要查看平板的统计信息，请使用`-m` (平板)选项。 您将需要使用`sudo` ，并且将提示您输入密码。 由于输出可能会很长，因此我们正在通过`less`管道进行输出。

sudo vmstat -m | less

![sudo vmstat -m | less in a terminal window][sudo vmstat -m _ less in a terminal window]

The output has five columns. These are:

输出有五列。 这些是：

*  *Cache*: Name of the cache.
    
    *缓存* ： *缓存的*名称。
 *  *num*:  The number of currently active objects in this cache.
    
    *num* ：此缓存中当前活动对象的数量。
 *  *total*:  The total number of available objects in this cache.
    
    *total* ：此缓存中可用对象的总数。
 *  *size*:  The size of each object in the cache.
    
    *size* ：缓存中每个对象的大小。
 *  *pages*:  The total number of memory pages that have (at least) one object currently associated with this cache.
    
    *pages* ：具有(至少)当前与此高速缓存关联的对象的内存页面总数。

![output from sudo vmstat -m | less ina terminal window][output from sudo vmstat -m _ less ina terminal window]

Press `q` to leave `less`.

按`q`留下`less` 。

## 显示事件计数器和内存统计信息 **(**Displaying Event Counters and Memory Statistics**)** ##

To display a page of event counters and memory statistics, use the `-s` (stats) option. Note that’s a lowercase “s.”

要显示事件计数器和内存统计信息的页面，请使用`-s` (stats)选项。 请注意，这是一个小写的“ s”。

vmstat -s

![vmstat -s in a terminal window][]

Although the statistics that are reported are largely the same as the information that makes up the default `vmstat` output, some of them are split out in more detail.

尽管报告的统计信息与构成默认`vmstat`输出的信息基本相同，但其中的一些信息会更详细地拆分。

For example, the default output combines both the nice and the non-nice user CPU time into the “us” column. The -s (stats) display lists these statistics separately.

例如，默认输出将“ nice”和“ nice”用户的CPU时间都合并到“ us”列中。 -s(统计信息)显示单独列出这些统计信息。

![output from vmstat -s in aterminal window][]

## 显示磁盘统计信息 **(**Displaying Disk Statistics**)** ##

You can obtain a similar listing of disk statistics using the `-d` (disk) option.

您可以使用`-d` (磁盘)选项获得类似的磁盘统计信息列表。

vmstat -d | less

![vmstat -d | less in a terminal window][vmstat -d _ less in a terminal window]

For each disk, three columns are displayed, these are Reads, Writes, and IO.

对于每个磁盘，将显示三列，分别是读取，写入和IO。

![output from vmstat -d | less in a terminal window][output from vmstat -d _ less in a terminal window]

IO is the rightmost column. Note that the sec column in IO is measured in seconds but the time-based statistics in the read and write columns are measured in milliseconds.

IO是最右边的列。 请注意，IO中的sec列以秒为单位，而读和写列中基于时间的统计信息以毫秒为单位。

![output vmstat -d | less in a terminal window][output vmstat -d _ less in a terminal window]

This is what the columns mean:

这是列的含义：

Reads

读

*  *total*: The total count of disk reads.
    
    *total* ：磁盘读取总数。
 *  *merged*: The total count of grouped reads.
    
    *合并的* ：分组读取的总数。
 *  *sectors*: The total count of sectors that have been read in.
    
    *ectors* ：已读入的扇区总数。
 *  *ms*: Total count of time in milliseconds that were used reading data from the disk.
    
    *ms* ：从磁盘读取数据所用的总时间(以毫秒为单位)。

writes

写

*  *total*: The total count of disk writes.
    
    *total* ：磁盘写入总数。
 *  *merged*: The total count of grouped writes.
    
    *merged* ：分组写入的总数。
 *  *sectors*: The total count of sectors written to.
    
    *扇区* ：写入的扇区总数。
 *  *ms* = Total count of time in milliseconds that were used writing data to the disk.
    
    *ms* =用于将数据写入磁盘的总时间(以毫秒为单位)。

*  *cur:* Number of current disk reads or writes.
    
    *cur：*当前磁盘读取或写入的次数。
 *  *sec: *Time spent in seconds for any in-progress reads or writes.
    
    *sec：*正在进行的任何读取或写入所花费的时间(以秒为单位)。

## 显示摘要磁盘统计信息 **(**Displaying Summary Disk Statistics**)** ##

To see a quick display of summary statistics for your disk activity, use the `-D` (disk-sum) option. Note the uppercase “D.”

要快速查看磁盘活动的摘要统计信息，请使用`-D` (磁盘和)选项。 注意大写字母“ D”。

vmstat -D

![vmstat -D in a terminal window][]

The number of disks might look abnormally high. The computer used to research this article is running Ubuntu. With Ubuntu, each time you install an application from a Snap, a `squashfs` pseudo-filesystem is created which is attached to a /dev/loop device.

磁盘数量可能看起来异常高。 用于研究本文的计算机正在运行Ubuntu。 使用Ubuntu，每次从Snap安装应用程序时，都会创建一个`squashfs`伪文件系统，该文件系统附加到/ dev / loop设备。

Annoyingly these device entries are counted as hard drive devices by many of the Linux commands and utilities.

令人讨厌的是，许多Linux命令和实用程序都将这些设备条目算作硬盘设备。

![output from vmstat -D in a terminal window][]

## 显示分区统计信息 **(**Displaying Partition Statistics**)** ##

To see statistics related to a specific partition, use the `-p` (partition) option and provide the partition identifier as a command line parameter.

要查看与特定分区相关的统计信息，请使用`-p` (分区)选项，并提供分区标识符作为命令行参数。

Here we are going to look at the partition `sda1`. The digit one indicates this is the first partition on device `sda`, which is the main hard drive for this computer.

在这里，我们将看一下分区`sda1` 。 数字1表示这是设备`sda`上的第一个分区，它是此计算机的主硬盘驱动器。

vmstat -p sda1

![vmstat -p in a terminal window][]

The information returned shows the total count of disk reads and disk writes to and from that partition, and the number of sectors included in disk read and disk write actions.

返回的信息显示了对该分区进行磁盘读取和磁盘写入的总数，以及磁盘读取和磁盘写入操作中包含的扇区数。

![output from vmstat -p sda1 in a terminal window][]

## 偷看之下 **(**A Peek Under The Hood**)** ##

It’s always good to know how to lift the hood and see what’s going on underneath. Sometimes you’ll be trying to problem solve, sometimes it’ll be out of interest because you want to know how your computer ticks.

知道如何抬起引擎盖并查看下方的状况总是很高兴。 有时您会尝试解决问题，而有时则可能会因为您想了解计算机的运行状况而失去兴趣。

`vmstat` can provide you with a ton of useful information. Now you know how to access it and what it means. And forewarned is forearmed—when you do need to roll your sleeves up and do some diagnostics, you’ll know you’ve got `vmstat` on your side.

`vmstat`可以为您提供大量有用的信息。 现在，您知道如何访问它及其含义。 可以预先警告，当您确实需要卷起袖子并进行一些诊断时，您会知道`vmstat`在您身边。

> 翻译自: [https://www.howtogeek.com/424334/how-to-use-the-vmstat-command-on-linux/][https_www.howtogeek.com_424334_how-to-use-the-vmstat-command-on-linux]

[Terminal prompt on a Linux desktop]: /images/20210726/ebcdcb3debc14276ae92d0365bb7fab4.png
[Fatmawati Achmad Zaenuri_Shutterstock.com]: https://www.shutterstock.com/image-vector/linux-interface-screen-notebook-world-map-321627716
[random access memory]: https://en.wikipedia.org/wiki/Random-access_memory
[Unix-like]: https://www.howtogeek.com/182649/htg-explains-what-is-unix/
[virtual memory statistics]: http://man7.org/linux/man-pages/man8/vmstat.8.html
[vmstat in a terminal window]: /images/20210726/41ea9bf7079d44c1926f185d63ecd8e8.png
[vmstat output in a terminal window]: /images/20210726/22a992a6367e4c64b3179d5d54979ca7.png
[vmstat output right-hand columns in a terminal window]: /images/20210726/d0ed0e6955434012895b6bbe34335353.png
[vmstat 5 in a terminal window]: /images/20210726/e8b61f0c469a431ea55260cc4de428f9.png
[output from vmstat 5 in a terminal window]: /images/20210726/c08016c6880e4f32b32b20be5a334145.png
[vmstat 5 4 in a terminal window]: /images/20210726/93a33c9177574148a4ff0e7148147d9e.png
[output from vmstat 5 4 in a terminal window]: /images/20210726/cd2f4c20a6e846bb8f56003a40c44c74.png
[vmstat 10 -S M ina terminal window]: /images/20210726/6bc8cc4eed98446988d6bbe47baf05ef.png
[output from vmstat 10 -S M ina terminal window]: /images/20210726/ad17c153c1af4806a070f8923e695d36.png
[vmstat 5 -a -S M in a terminal window]: /images/20210726/9cffad8736e447c3b5822c56830c2407.png
[output from vmstat 5 -a -S M in a terminal window]: /images/20210726/2657c9dd963f4e589498ca0057329bd5.png
[vmstat -f in a terminal window]: /images/20210726/109fee5ffc1d4a70a0806fd02e6730de.png
[sudo vmstat -m _ less in a terminal window]: /images/20210726/9e205ba8111f4941bc8780f6d88e128c.png
[output from sudo vmstat -m _ less ina terminal window]: /images/20210726/22b4364f2e9d43ce8c360a9a7a92a069.png
[vmstat -s in a terminal window]: /images/20210726/60bdc4cca8704a1ca2a6050d996e1351.png
[output from vmstat -s in aterminal window]: /images/20210726/3f6f4e73a6c348bf80f457ece6ea583c.png
[vmstat -d _ less in a terminal window]: /images/20210726/7a7dc0603714407799c9f589a71f222b.png
[output from vmstat -d _ less in a terminal window]: /images/20210726/5ebf713b7dc34034bf8ced3ce60a7773.png
[output vmstat -d _ less in a terminal window]: /images/20210726/8f68cf8ea3c5412899777d3c6c6771a8.png
[vmstat -D in a terminal window]: /images/20210726/6b535ca14d5c4447a8b4dccf16d04d84.png
[output from vmstat -D in a terminal window]: /images/20210726/58614c9a633e4444b1bb8568d75c60fe.png
[vmstat -p in a terminal window]: /images/20210726/ca132014411442658a935a0ee7f065fa.png
[output from vmstat -p sda1 in a terminal window]: /images/20210726/108e78f023c44099a6e4d264104d68c7.png
[https_www.howtogeek.com_424334_how-to-use-the-vmstat-command-on-linux]: https://www.howtogeek.com/424334/how-to-use-the-vmstat-command-on-linux/