9個必須掌握的Linux性能調(diào)優(yōu)命令和工具

時間：2020-11-15 23:15:36

關(guān)鍵字： Linux 嵌入式

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[導(dǎo)讀]本文介紹了Linux查看資源使用情況和性能調(diào)優(yōu)常用的命令，包括top、htop、ps、free、vmstat、iostat、netstat、df和du命令。

CPU使用率：數(shù)字1、2、...表示CPU有幾個核，后面的進度條用不同顏色來表示不同維度的CPU使用率，最后是CPU使用率；
內(nèi)存使用率：Mem后面的進度條用不同顏色來表示不同維度的內(nèi)存使用率（綠色：used，藍色：buffers，橙色：cache)，最后是內(nèi)存使用率（used / total);
Swap使用率：Swap后面的進度條顯示已用的Swap，最后是Swap使用率（used / total)，如果系統(tǒng)關(guān)閉了Swap，則進度條為空，Swap使用率為0K/0K；
進程和線程統(tǒng)計：Tasks：進程數(shù)，thr：線程數(shù)，running：正在運行的進程數(shù)；
系統(tǒng)平均負載統(tǒng)計：Load average：前1分鐘平均負載、前5分鐘平均負載和前15分鐘平均負載；負載越低說明CPU越空閑，負載越高說明CPU越忙：

負載低于0.7 * CPU核數(shù)：CPU使用率正常；（道路通暢）
負載高于0.7 * CPU核數(shù)：CPU使用率較高，需要關(guān)注；（道路堵車，需要交警到場疏導(dǎo)交通）
負載高于1 * CPU核數(shù)：CPU使用率過高，需要關(guān)注；（道路嚴重堵車，可能發(fā)生了交通事故，需要交警馬上到現(xiàn)場處理）
負載高于5 * CPU核數(shù)：系統(tǒng)超負荷運轉(zhuǎn)，無法正常響應(yīng)；（交通癱瘓，可能道路已經(jīng)被水淹無法通行，需要投入搶險力量恢復(fù)交通）

系統(tǒng)已連續(xù)運行時間：Uptime后面為系統(tǒng)從上次啟動后，已連續(xù)運行時間，可以倒推系統(tǒng)上次啟動時間；

詳細信息說明：

PID：進程ID；
USER：進程所有者；
PRI：進程優(yōu)先級；
NI：nice值，負值表示高優(yōu)先級，正值表示低優(yōu)先級；
VIRT：進程使用的虛擬內(nèi)存(virtual memory)；
RES：進程使用的物理內(nèi)存(physical memory)；
SHR：進程使用的共享內(nèi)存（shared memory);
S：進程狀態(tài)，R（Running）正在運行的進程、S（Sleeping）休眠的進程、T/S(Traced/Stopped) 已停止或中止的進程或 Z（Zommbie）僵尸進程；
CPU%：進程使用的CPU時間百分比；
MEM%：進程使用的內(nèi)存百分比；
TIME+：進程已連續(xù)運行時間；
Command：進程的執(zhí)行命令；

常用快捷鍵：

上下箭頭：上下滾動查看進程；
u：顯示指定用戶的進程；
P：按照進程使用的CPU時間百分比排序；
M：按照進程使用的內(nèi)存百分比排序；
T：按照進程已連續(xù)運行時間排序；

參考：

https://linuxtogether.org/htop-command-explanation/
https://www.softprayog.in/tutorials/htop-command-in-linux
https://scoutapm.com/blog/understanding-load-averages
htop官網(wǎng)

ps命令

#?查看java進程
#?e(every)?所有進程
#?f(full?format)?完整輸出格式
ps?-ef?|?grep?nginx

#?不顯示grep本身
ps?-ef?|?grep?nginx?|?grep?-v?grep

#?獲取指定進程的PID
ps?-ef?|?grep?java?|?grep?jenkins?|?grep?-v?grep?|?awk?'{print?$2}'

#?根據(jù)進程的PID中止進程
ps?-ef?|?grep?java?|?grep?jenkins?|?grep?-v?grep?|?awk?'{print?$2}'?|?xargs?kill?-9

#?查看進程堆棧
#?p(path)?顯示完整路徑
pmap??-p

#?查看9091端口是哪個容器進程
docker?ps?|?grep?9091

ps -ef格式：

UID：進程的UID（用戶）
PID：進程ID
PPID：父進程ID
C：CPU使用時間百分比
STIME
TTY
TIME
CMD：啟動進程的命令

free命令

free命令用來查看內(nèi)存和Swap的使用情況。

命令：

#?以適合閱讀的形式輸出(h:?human)
free?-h

#?以MB格式輸出（m:?MB)
free?-m

#?合計Mem和Swap(t:?total)
free?-h?-t

#?統(tǒng)計3次，每秒1次(c:?count)
free?-h?-c?3

#?統(tǒng)計5次，每2秒統(tǒng)計1次(s:?second)
free?-h?-t?-c?5?-s?2

說明：

Total: The amount of RAM installed in your system.
Used: Equal to? Total-( Free+ Buffers+ Cache).
Free: The amount of memory completely unused by anything.
Shared: Memory taken by the? tmpfs?file systems.
Buffer: The data structures that are maintained to provide an index for everything stored in? Cache.
Cache: Data read from the hard drive, modified data waiting to be written back to the hard drive, and other computed values.
Available: What’s really free. An estimate of the memory in? Free,? Buffer, and? Cache?that could be used to satisfy a memory request.

簡單來說，total是系統(tǒng)總內(nèi)存，used就是系統(tǒng)已用內(nèi)存，total - used 就是系統(tǒng)可用內(nèi)存。

參考：

https://www.howtogeek.com/456943/how-to-use-the-free-command-on-linux/

vmstat命令

vmstat命令用來統(tǒng)計進程、內(nèi)存、Swap、IO和CPU等信息。

命令：

#?運行vmstat
vmstat

#?每5秒統(tǒng)計1次
vmstat?5

#?每5秒統(tǒng)計1次，共統(tǒng)計4次
vmstat?5?4

#?以MB格式輸出內(nèi)存使用情況
vmstat?5?4?-S?M

#?顯示統(tǒng)計概要信息
vmstat?-s

說明：

Proc

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.
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.

Memory

swpd: the amount of virtual memory used. In other words, how much memory has been swapped out.,
free: the amount of idle (currently unused) memory.
buff: the amount of memory used as buffers.
cache: the amount of memory used as cache.

Swap

si: Amount of virtual memory swapped? in?from swap space.
so: Amount of virtual memory swapped? out?to swap space.

bi: Blocks received from a block device. The number of data blocks used to swap virtual memory back into RAM.
bo: Blocks sent to a block device. The number of data blocks used to swap virtual memory out of RAM and into swap space.

System

in: The number of interrupts per second, including the clock.
cs: The number of context switches per second. A context switch is when the kernel swaps from system mode processing into user mode processing.

CPU

These values are all percentages of the total CPU time.

us: Time spent running non-kernel code. That is, how much time is spent in user time processing and in nice time processing.
sy: Time spent running kernel code.
id: Time spent idle.
wa: Time spent waiting for input or output.
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.

參考：

https://www.howtogeek.com/424334/how-to-use-the-vmstat-command-on-linux/
https://www.tecmint.com/linux-performance-monitoring-with-vmstat-and-iostat-commands/

iosat命令

iostat命令用來統(tǒng)計磁盤IO和CPU等信息。

命令：

#?運行iostat
iostat

#?以MB格式輸出
iostat?-m

#?查看指定磁盤（分區(qū)）
iostat?-m?-p?vda

#?每2秒統(tǒng)計一次，共統(tǒng)計3次
iostat?-m?2?3

說明：

CPU信息：

%user :?It shows the percentage of CPU being utilization that while executing at the user level.
%nice :?It shows the percentage of CPU utilization that occurred while executing at the user level with a nice priority.
%system :?It shows the percentage of CPU utilization that occurred while executing at the system (kernel) level.
%iowait :?It shows the percentage of the time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request.
%steal :?It shows the percentage of time being spent in involuntary wait by the virtual CPU or CPUs while the hypervisor was servicing by another virtual processor.
%idle :?It shows the percentage of time that the CPU or CPUs were idle and the system did not have an outstanding disk I/O request.

磁盤信息：

Device :?The device/partition name is listed in? /dev?directory.
tps :?The number of transfers per second that were issued to the device. Higher tps means the processor is busier.
Blk_read/s :?It shows the amount of data read from the device expressed in a number of blocks (kilobytes, megabytes) per second.
Blk_wrtn/s :?The amount of data written to the device expressed in a number of blocks (kilobytes, megabytes) per second.
Blk_read :?It shows the total number of blocks read.
Blk_wrtn :?It shows the total number of blocks written.

參考：

https://www.geeksforgeeks.org/iostat-command-in-linux-with-examples/
https://www.techrepublic.com/article/how-to-use-the-linux-iostat-command-to-check-on-your-storage-subsystem/

netstat命令

netstat命令用來統(tǒng)計網(wǎng)絡(luò)連接和端口等信息。

命令：

#?顯示在偵聽的TCP/UDP網(wǎng)絡(luò)連接，包括程序和端口信息
#?u(UDP)
#?t(TCP)
#?n(port)
#?l(listen)
#?p(program)
netstat?-utnlp

#?只顯示在偵聽的TCP網(wǎng)絡(luò)連接，包括程序和端口信息
netstat?-tnlp

#?查看某個端口被哪個進程使用
#?a(all)
netstat?-anp?|?grep?6379

#?查看某個進程在哪個端口
netstat?-anp?|?grep?redis

#?查看docker啟動的進程在哪個端口
docker?ps?|?grep?jenkins

df命令

df命令用來統(tǒng)計磁盤使用情況。

命令：

#?查看全部文件系統(tǒng)的磁盤使用情況
df?-h

#?查看指定目錄所在的文件系統(tǒng)的磁盤使用情況
df?-h?~

#?不顯示docker文件系統(tǒng)
df?-h?|?grep?-v?docker

du命令

du命令用來統(tǒng)計指定目錄的大小。

命令：

#?統(tǒng)計某個目錄大小
du?-sh?~

#?統(tǒng)計目錄下各個子目錄和文件的大小
du?-h?~

#?統(tǒng)計目錄下各個子目錄和文件的大小，并顯示合計大小
du?-ch?~

#?只統(tǒng)計下一級目錄大小
du?-h?--max-depth?1

#?只統(tǒng)計下一級目錄大小，單位為MB，從大到小排序
du?-m?--max-depth?1?|?sort?-rn

#?只統(tǒng)計下一級目錄大小，單位為MB，從大到小排序，返回最大的10個文件（目錄）
du?-m?--max-depth?1?|?sort?-rn?|?head?-11