8.14 process accounting

8.14 process accounting

Process accounting是将每一个进程的启动，退出，时间，用户，命令，资源使用，等信息做出记录，写在一个记录文件上的系统服务，可以用来查询，该记录是2进制文件。有的系统并没有安装这一项服务。系统每次fork出一个进程，都会在process table里增加一个entry，然后当该进程退出的时候，将该信息记录在系统的记录文件中。

typedef  u_short comp_t;   /* 3-bit base 8 exponent; 13-bit fraction */

struct  acct

{

  char   ac_flag;     /* flag (see ) */

  char   ac_stat;     /* termination status (signal & core flag only) */

                      /* (Solaris only) */

  uid_t  ac_uid;      /* real user ID */

  gid_t  ac_gid;      /* real group ID */

  dev_t  ac_tty;      /* controlling terminal */

  time_t ac_btime;    /* starting calendar time */

  comp_t ac_utime;    /* user CPU time (clock ticks) */

  comp_t ac_stime;    /* system CPU time (clock ticks) */

  comp_t ac_etime;    /* elapsed time (clock ticks) */

  comp_t ac_mem;      /* average memory usage */

  comp_t ac_io;       /* bytes transferred (by read and write) */

                      /* "blocks" on BSD systems */

  comp_t ac_rw;       /* blocks read or written */

                      /* (not present on BSD systems) */

  char   ac_comm[8];  /* command name: [8] for Solaris, */

                      /* [10] for Mac OS X, [16] for FreeBSD, and */

                      /* [17] for Linux */

};