14:29:30 statfs("/u01/app/oracle/sqlplus/admin/glogin.sql", {f_type="EXT2_SUPER_MAGIC", f_bsize=4096, f_blocks=174170552, f_bfree=147038317, f_bavail=138190970, f_files=44236800, f_ffree=44019066, f_fsid={1821877354, 763674030}, f_namelen=255, f_frsize=4096}) = 0
14:29:30 open("/u01/app/oracle/sqlplus/admin/glogin.sql", O_RDONLY) = 7
4、跟踪执行进程方式
除了上面介绍的方法外，strace还可以直接跟踪监控正在执行的系统进程。下面我们来观察一下strace对Oracle后台CKPT进程的监控。
[oracle@XXX-Standby-Asm ~]$ ps -ef | grep ckpt
grid 15950 1 0 Jun05 ? 00:01:02 asm_ckpt_+ASM
oracle 18608 17848 0 17:35 pts/0 00:00:00 grep ckpt
oracle 21395 1 0 Jun08 ? 00:04:27 ora_ckpt_xxxstb
从root角度，跟踪进程编号21395的后台进程。
[root@XXX-Standby-Asm ~]# strace -t -p 21395
Process 21395 attached - interrupt to quit
17:36:42 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608271
17:36:42 semtimedop(6062085, {{16, -1, 0}}, 1, {1, 840000000}) = -1 EAGAIN (Resource temporarily unavailable)
17:36:44 getrusage(RUSAGE_SELF, {ru_utime={125, 122978}, ru_stime={142, 730301}, ...}) = 0
17:36:44 getrusage(RUSAGE_SELF, {ru_utime={125, 122978}, ru_stime={142, 730301}, ...}) = 0
17:36:44 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608455
17:36:44 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608455
17:36:44 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:44 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:44 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608455
17:36:44 semtimedop(6062085, {{16, -1, 0}}, 1, {3, 0}) = -1 EAGAIN (Resource temporarily unavailable) –三秒差异
17:36:47 getrusage(RUSAGE_SELF, {ru_utime={125, 123978}, ru_stime={142, 731301}, ...}) = 0
17:36:47 getrusage(RUSAGE_SELF, {ru_utime={125, 123978}, ru_stime={142, 731301}, ...}) = 0
17:36:47 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608755
17:36:47 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608755
17:36:47 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:47 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:47 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:47 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:47 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:47 read(16, "MSA\0\2\0\10\0P\0\0\0\0\0\0\0\20?P\r\0\0\0\0\0\200\330\266\177\177\0\0"..., 80) = 80
17:36:47 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608756
17:36:47 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608756
17:36:47 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608756
17:36:47 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608756
17:36:47 times({tms_utime=12512, tms_stime=14273, tms_cutime=0, tms_cstime=0}) = 645608756
17:36:47 semtimedop(6062085, {{16, -1, 0}}, 1, {3, 0}^C
Process 21395 detached
从里面，我们可以看到ckpt的动作方式。
5、结论
Strace是Linux环境下的一个非常有用的工具。用好这个工具，可以让我们更加接近内核细节，丰富知识能力。