Linux 下各种监控系统的命令小结

最新推荐文章于 2025-12-26 11:06:25 发布

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#操作系统

Linux 下各种监控系统的命令小结

linux 里面监控了各种系统资源，也采取了不同的命令，这里说下几种常用的命令

1、 top 命令

以下是 top 命令中，几个关键字段的含义

Table 17-1. top Column headers

Header Meaning

PID Tasks process ID. This unique identifier allows you to manipulate a task.

USER The user name of the tasks owner, the account it runs as.

PR The task priority.

NI The task niceness, an indication of how willing this task is to yield CPU cycles to other tasks. A lower or negative niceness means a high priority.

VIRT The total amount of memory used by the task, including shared and swap memory.

RES The total amount of physical memory used by the task, excluding swap memory.

SHR The amount of shared memory used by the task. This memory is usually allocated by libraries and also usable by other tasks.

S Task status. This indicates whether a task is running (R), sleeping (D or S), stopped (T),or zombie (Z).

%CPU Percentage of available CPU cycles this task has used since the last screen update.

%MEM Percentage of available RAM used by this task. --记住，这里不包括 swap

TIME+ Total CPU time the task has used since it started.

COMMAND The name of the task being monitored.

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还有一点要记住，top 命令对于 cpu 不是叠加的，也就是说，如果有 8个 cpu，那么，有可能 top 出来的某个 pid 的 cpu 占有率已经 100% 了，我们只能说这个程序耗掉了一个 cpu 的资源，其它 cpu 可能是空闲的。

2、 vmstat

以下是从 man vmstat 里面摘抄出来的 vmstat 的解释：

Procs --process

r: The number of processes waiting for run time.

b: The number of processes in uninterruptible sleep.

Memory

swpd: the amount of virtual memory used.

free: the amount of idle memory.

buff: the amount of memory used as buffers.

cache: the amount of memory used as cache.

inact: the amount of inactive memory. (-a option)

active: the amount of active memory. (-a option)

Swap

si: Amount of memory swapped in from disk (/s).

so: Amount of memory swapped to disk (/s).

bi: Blocks received from a block device (blocks/s).

bo: Blocks sent to a block device (blocks/s).

System

in: The number of interrupts per second, including the clock.

cs: The number of context switches per second.

CPU

These are percentages of total CPU time.

us: Time spent running non-kernel code. (user time, including nice time)

sy: Time spent running kernel code. (system time)

id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.

wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.

st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.

这里，我重点说下 swap 、IO 和 CPU 这三个值

首先说下 swap 和 CPU 的 wa

当 os 出现性能下降时，我们通过 vmstat 观察发现 swap 的 si和 so 两项值特别高时，我们就应该注意，是不是 os 的内存不够用，导致了过度的 swap 的 page in 和page out，而当 swap 的si 和so 值较高时，往往 CPU 的wa 值也很高，这个 wa 值表示cpu 花在等待 swap 数据的时间。所以，一旦这三个指标都很高时，就要注意，应用是否占用了过多的内存，导致了 swap 不断得 page in 和page out