linux主机cpu 占用过高分析

原文地址：http://blog.sina.com.cn/s/blog_48eef8410101fl4p.html

1.用top命令查看哪个进程占用CPU高

gateway网关进程14094占用CPU高达891%，这个数值是进程内各个线程占用CPU的累加值。

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

14094 root 15 0 315m 10m 7308 S 891% 2.2 1:49.01 gateway

20642 root 17 0 17784 4148 2220 S 0.5 0.8 2:39.96 microdasys

1679 root 18 0 10984 1856 1556 R 0.3 0.4 0:22.21 sshd

22563 root 18 0 2424 1060 800 R 0.3 0.2 0:00.03 top

1 root 18 0 2156 492 460 S 0.0 0.1 0:01.59 init

2.用top -H -p pid命令查看进程内各个线程占用的CPU百分比

top -H -p 14094

top中可以看到有107个线程，但是下面9个线程占用CPU很高，下面以线程14086为主，分析其为何high CPU

PID USER PR NI VIRT RES SHR S %CPU MEM TIME+ COMMAND

14086 root 25 0 922m 914m 538m R 101 10.0 21:35.46 gateway

14087 root 25 0 922m 914m 538m R 101 10.0 10:50.22 gateway

14081 root 25 0 922m 914m 538m S 99 10.0 8:57.36 gateway

14082 root 25 0 922m 914m 538m R 99 10.0 11:51.92 gateway

14089 root 25 0 922m 914m 538m R 99 10.0 21:21.77 gateway

14092 root 25 0 922m 914m 538m R 99 10.0 19:55.47 gateway

14094 root 25 0 922m 914m 538m R 99 10.0 21:02.21 gateway

14083 root 25 0 922m 914m 538m R 97 10.0 21:32.39 gateway

14088 root 25 0 922m 914m 538m R 97 10.0 11:23.12 gateway

3.使用gstack命令查看进程中各线程的函数调用栈

gstack 14094 > gstack.log

在gstack.log中查找线程ID14086，由于函数栈会暴露函数细节，因此只显示了两个函数桢，线程ID14086对应线程号是37

Thread 37 (Thread 0x4696ab90 (LWP 14086)):

0 0x40000410 in __kernel_vsyscall ()

1 0x40241f33 in poll () from /lib/i686/nosegneg/libc.so.6