job - Linux Jobs kernel module overiew


DESCRIPTION

       A job is a group of related processes all descended from a
       point of entry process and  identified  by  a  unique  job
       identifier  (jjiidd).   A  job  can  contain multiple process
       groups or sessions, and all processes in one of these sub­
       groups can only be contained within a single job.

       The  primary  purpose  for  having  jobs is to provide job
       based resource limits.  The  current  implementation  only
       provides  the  job  container  and resource limits will be
       provided in a later implementation.  When  an  implementa­
       tion  that provides job limits is available, this descrip­
       tion will be expanded to provide  further  explanation  of
       job based limits.

       Not  every  process  on the system is part of a job.  That
       is, only processes which are started by a login  initiator
       like  login, rlogin, rsh and so on, get assigned a job ID.
       In the Linux environment, jobs are created via a PAM  mod­
       ule.

       Jobs on Linux are provided using a loadable kernel module.
       Linux jobs have the following characteristics:

       ·   A job is an inescapable container.  A  process  cannot
           leave the job nor can a new process be created outside
           the job without explicit action,  that  is,  a  system
           call with root privilege.

       ·   Each  new  process  inherits  the jjiidd and limits [when
           implemented] from its parent process.

       ·   All point of entry processes (job initiators) create a
           new  job  and  set  the  job limits [when implemented]
           appropriately.

       ·   Job initiation on Linux is performed via a PAM session
           module.

       ·   The job initiator performs authentication and security
           checks.

       ·   Users can raise and lower their own job limits  within
           maximum  values  specified by the system administrator
           [when implemented].

       ·   Not all pocesses on a system need be members of a job.

       ·   The  process control initialization process (init(1M))
           and startup scripts called by init are not part  of  a
           job.

       batch processes.  Limit domain names are  defined  by  the
       system  administrator when the user limits database (ULDB)
       is created.  [The ULDB will be implemented in  conjunction
       with future job limits work.]

       NNoottee:: The existing command jobs(1) applies to shell "jobs"
       and it is not related to the  Linux  Kernel  Module  jobs.
       The  at(1),  atd(8),  atq(1), batch(1), atrun(8), atrm(1))
       man pages refer to  shell  scripts  as  a  job.   a  shell
       script.


SEE ALSO

       job(1), jwait(1), jstat(1), jkill(1)


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