转自： http://blog.csdn.net/ligt0610/article/details/7265903
1、用top命令找到CPU利用率最高的进程
root@XXX:/# top
top - 09:36:26 up 22 min, 2 users, load average: 6.02, 5.10, 3.58
Tasks: 43 total, 1 running, 42 sleeping, 0 stopped, 0 zombie
Cpu(s): 1.0%us, 12.6%sy, 0.0%ni, 86.4%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 514336k total, 53156k used, 461180k free, 6776k buffers
Swap: 0k total, 0k used, 0k free, 24072k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1145 root 20 0 539m 6008 2940 S 65.9 1.2 2:40.77 test.out
6 root 15 -5 0 0 0 S 0.3 0.0 0:00.13 khelper
1327 root 20 0 3352 1372 1136 S 0.3 0.3 0:02.01 run
12465 root 20 0 8432 2300 1932 S 0.3 0.4 0:00.07 sshd
1 root 20 0 2436 704 616 S 0.0 0.1 0:00.73 init
2 root 15 -5 0 0 0 S 0.0 0.0 0:00.00 kthreadd
2、找到对应进程占用CPU时间最长的线程
root@XXX:/#ps -efL | grep test.out | grep -v grep
UID PID PPID LWP C NLWP STIME TTY TIME CMD
root 1145 1 1145 0 62 09:14 ? 00:00:03 /home/ligt/bin/test.out
root 1145 1 1148 0 62 09:14 ? 00:00:01 /home/ligt/bin/test.out
root 1145 1 1149 0 62 09:14 ? 00:00:03 /home/ligt/bin/test.out
root 1145 1 1151 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1152 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1153 0 62 09:14 ? 00:00:06 /home/ligt/bin/test.out
root 1145 1 1154 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1155 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1157 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1158 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1159 0 62 09:14 ? 00:00:06 /home/ligt/bin/test.out
root 1145 1 1160 0 62 09:14 ? 00:00:01 /home/ligt/bin/test.out
root 1145 1 1161 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1162 10 62 09:14 ? 00:02:41 /home/ligt/bin/test.out
root 1145 1 1163 0 62 09:14 ? 00:00:01 /home/ligt/bin/test.out
root 1145 1 1164 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1165 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1166 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1167 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1169 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1170 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1171 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1172 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1173 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1174 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1175 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1176 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1177 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1178 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1179 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1180 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1181 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1182 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1183 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1186 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1187 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1188 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1189 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1192 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1193 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1194 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1195 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1196 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1197 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1198 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1199 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1200 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1201 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1202 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1203 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1204 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1205 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1206 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1207 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
root 1145 1 1208 0 62 09:14 ? 00:00:00 /home/ligt/bin/test.out
3、 attach到对应的线程上
root@XXX:/#gdb attach 1162
GNU gdb (Wind River Linux Sourcery G++ 4.3a-274) 6.8.50.20080821-cvs
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "powerpc-wrs-linux-gnu".
For bug reporting instructions, please see:
<support@windriver.com>...
attach: No such file or directory.
Attaching to process 1162
warning: process 1162 is a cloned process
Reading symbols from /common/home/ligt/bin/test.out...done.
Reading symbols from /lib/libcrypt.so.1...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /usr/lib/libmscm_auth.so...done.
Loaded symbols for /usr/lib/libmscm_auth.so
Reading symbols from /usr/lib/libmscm_ldap.so...done.
Loaded symbols for /usr/lib/libmscm_ldap.so
Reading symbols from /usr/lib/libmscm_cfgparse.so...done.
Loaded symbols for /usr/lib/libmscm_cfgparse.so
Reading symbols from /usr/lib/libldap-2.4.so.2...done.
Loaded symbols for /usr/lib/libldap-2.4.so.2
Reading symbols from /usr/lib/liblber-2.4.so.2...done.
Loaded symbols for /usr/lib/liblber-2.4.so.2
Reading symbols from /lib/libdl.so.2...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /usr/lib/libstdc++.so.6...done.
Loaded symbols for /usr/lib/libstdc++.so.6
Reading symbols from /lib/libm.so.6...done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libgcc_s.so.1...done.
Loaded symbols for /lib/libgcc_s.so.1
Reading symbols from /lib/libpthread.so.0...done.
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /lib/libc.so.6...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/libresolv.so.2...done.
Loaded symbols for /lib/libresolv.so.2
Reading symbols from /lib/ld.so.1...done.
Loaded symbols for /lib/ld.so.1
Reading symbols from /lib/libnss_files.so.2...done.
Loaded symbols for /lib/libnss_files.so.2
0x0ff1dbf0 in select () from /lib/libc.so.6
(gdb) bt
#0 0x0ff1dbf0 in select () from /lib/libc.so.6
#1 0x101396cc in OSAL_TaskDelay (ulMillSecs=<value optimized out>)
at /home/ligt/IPMI/src/vos/ipmi_osal_task.c:498
#2 0x101307a8 in VOS_TaskDelay (ulMillSecs=<value optimized out>) at /home/ligt/IPMI/src/vos/ipmi_v_task.c:3512
#3 0x10089ed4 in CIPMB_Processor::OnSend (this=0x103cc0a8) at /home/ligt/IPMI/src/ipmi/ipmbproc.cpp:3422
#4 0x10132db8 in VOS_TaskEntry (pulArg=0x1000d) at /home/ligt/IPMI/src/vos/ipmi_v_task.c:3459
#5 0x0fdf6d8c in ?? () from /lib/libpthread.so.0
#6 0x0ff25a90 in clone () from /lib/libc.so.6
(gdb) q
The program is running. Quit anyway (and detach it)? (y or n) y
Detaching from program: /home/ligt/bin/test.out, process 1162
通过以上三步分析，基本可以定位哪些代码造成CPU占用率高的问题，希望对遇到同样问题的朋友有所帮助。