linux主機cpu 佔用過高分析
1.用top命令檢視哪個程序佔用CPU高
gateway閘道器程序14094佔用CPU高達891%，這個數值是程序內各個執行緒佔用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命令檢視程序內各個執行緒佔用的CPU百分比
top -H -p 14094
top中可以看到有107個執行緒，但是下面9個執行緒佔用CPU很高，下面以執行緒14086為主，分析其為何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命令檢視程序中各執行緒的函式呼叫棧
gstack 14094 > gstack.log
在gstack.log中查詢執行緒ID14086，由於函式棧會暴露函式細節，因此只顯示了兩個函式楨，執行緒ID14086對應執行緒號是37
Thread 37 (Thread 0x4696ab90 (LWP 14086)):
0 0x40000410 in __kernel_vsyscall ()
1 0x40241f33 in poll () from /lib/i686/nosegneg/libc.so.6