프로세스가 시작한 시간 구하기

python으로 개발된 child 프로그램이 타임아웃이 잘 먹지 않아서 cron 을 이용해서 실행된 후에 일정 시간이 지난 프로그램을 kill 하려고 합니다.
ps 명령어를 실행시켜서 보면 START 부분이 프로세스가 실행된 시간인데, /proc/PID/stat를 읽어와서 뿌려주는 것 같은데, stat에서 어떤 부분이 start time인지 알 수가 없네요.

$ cat stat
20804 (python) S 29977 29975 29975 0 -1 0 2478 25668 955 3410 16 22 87 36 15 0 0 6000 77954307 8777728 997 4294967295 134512640 135281960 3221222864 3221220600 4294959106 0 2147221247 16781313 8194 3222461405 0 0 17 1 0 0 16 22 87 36

참고로 구글에서 찾은바로는,

  int           pid;                      /** The process id. **/
  char          exName [_POSIX_PATH_MAX]; /** The filename of the executable **/
  char          state; /** 1 **/          /** R is running, S is sleeping, 
                           D is sleeping in an uninterruptible wait,
                           Z is zombie, T is traced or stopped **/
  unsigned      euid,                      /** effective user id **/
                egid;                      /** effective group id */                                         
  int           ppid;                     /** The pid of the parent. **/
  int           pgrp;                     /** The pgrp of the process. **/
  int           session;                  /** The session id of the process. **/
  int           tty;                      /** The tty the process uses **/
  int           tpgid;                    /** (too long) **/
  unsigned int  flags;                    /** The flags of the process. **/
  unsigned int  minflt;                   /** The number of minor faults **/
  unsigned int  cminflt;                  /** The number of minor faults with childs **/
  unsigned int  majflt;                   /** The number of major faults **/
  unsigned int  cmajflt;                  /** The number of major faults with childs **/
  int           utime;                    /** user mode jiffies **/
  int           stime;                    /** kernel mode jiffies **/
  int           cutime;                   /** user mode jiffies with childs **/
  int           cstime;                   /** kernel mode jiffies with childs **/
  int           counter;                  /** process's next timeslice **/
  int           priority;                 /** the standard nice value, plus fifteen **/
  unsigned int  timeout;                  /** The time in jiffies of the next timeout **/
  unsigned int  itrealvalue;              /** The time before the next SIGALRM is sent to the process **/
  int           starttime; /** 20 **/     /** Time the process started after system boot **/
  unsigned int  vsize;                    /** Virtual memory size **/
  unsigned int  rss;                      /** Resident Set Size **/
  unsigned int  rlim;                     /** Current limit in bytes on the rss **/
  unsigned int  startcode;                /** The address above which program text can run **/
  unsigned int  endcode;                  /** The address below which program text can run **/
  unsigned int  startstack;               /** The address of the start of the stack **/
  unsigned int  kstkesp;                  /** The current value of ESP **/
  unsigned int  kstkeip;                 /** The current value of EIP **/
  int           signal;                   /** The bitmap of pending signals **/
  int           blocked; /** 30 **/       /** The bitmap of blocked signals **/
  int           sigignore;                /** The bitmap of ignored signals **/
  int           sigcatch;                 /** The bitmap of catched signals **/
  unsigned int  wchan;  /** 33 **/        /** (too long) **/
  int           sched,            /** scheduler **/
                sched_priority;           /** scheduler priority **/

인데, 항목을 찾아보면 starttime에 해당하는 값은 1이네요. :?
끝자리가 맞지 않아 좀 이상하긴 하지만...