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• Visibility: Public
• Change Control: Stable
• Details:
  • Upon startup PBS server will start all schedulers which have their scheduling attribute set to "True"
    • "PBS_START_SCHED" pbs.conf variable is now deprecated and it's value will get overridden by schedulers "scheduling" attribute.
  • PBS server will connect to these schedulers on their respective host names and port number.
  • Scheduling cycles for all configured schedulers are started by PBS server when a job is queued, finished, when scheduling attribute is set to True or when scheduler_iteration is elapsed.
    • When a job gets queued or finished, server will check it's corresponding queue and try to connect to it's corresponding scheduler to run a scheduling cycle.
    • If a scheduler is already running a scheduling cycle while server will just wait for the previous cycle to finish before trying to start another one.
    • If job_accumulation_time is set then server will wait until that time has passed after the submission of a job before starting a new cycle.
  • Each scheduler queries whole universe of all schedulers, server, queues, nodes information(This is to avoid IFL changes) etc. from server. Thereafter it does the following.
    • It filters all the running, queued, exiting jobs from the queues it is associated with its partition/s.
    • It filters all the list of nodes which are associated with the partition/s managed by the scheduler.
    • It filters the list of all the global policies like run soft/hard limits set on the server object.
  • PBS's init script will now be reporting status of pbs server only. Schedulers will be managed by server and their status can be fetched using a qmgr command.
    • When pbs_server daemon is stopped using "qterm -s" then, it will also stop all the running scheduler processes.
    • pbs init script while shutting down pbs_server will use the "-s" option to qterm so that all schedulers also come down along with server.

Interface 8: Changes to pbs_rsub commandReservations

• Visibility: Public
• Change Control: Stable
• Details:
  • Reservations can now be submitted to a specific partition using a new "-p" option with pbs_rsub command.
  • "-p" option in pbs_rsub command takes partition name as input and makes pbs_server to trigger a scheduling cycle of the scheduler that is servicing the partition.
  • If a scheduler servicing the requested partition isn't up and running then pbs server will store the reservation with itself and mark it as "UNCONFIRMED" until it is able to trigger a scheduling cycle of the said schedulerIn a Multi-sched environment, reservations can be confirmed by any scheduler servicing their respective partitions.
  • After the reservations are confirmed they are assigned the partition their node solution came from.
  • A scheduler servicing 2 partitions P1, P2 would try to confirm a reservation on nodes from either P1 or P2 but not a mix of both. Once the reservation is confirmed, it has a partition attribute set on it to identify where it was confirmed. Similarly, the reservation queue also gets a partition attribute set on it (matching the reservation).
    • example,

      % pbs_rsub -lselect=1:ncpus=2 -R 1030 -D1200 -I 5
      R865.centos CONFIRMED

      % pbs_rstat -f R865
      Resv ID: R865.centos
      Reserve_Name = NULL
      Reserve_Owner = root@centos
      reserve_type = 2
      reserve_state = RESV_CONFIRMED
      reserve_substate = 2
      reserve_start = Mon Feb 03 10:30:00 2020
      reserve_end = Mon Feb 03 10:50:00 2020
      reserve_duration = 1200
      queue = R865
      Resource_List.ncpus = 2
      Resource_List.nodect = 1
      Resource_List.select = 1:ncpus=2
      Resource_List.place = free
      Resource_List.walltime = 00:20:00
      schedselect = 1:ncpus=2
      resv_nodes = (vnode2:ncpus=2)
      Authorized_Users = root@centos
      server = centos
      ctime = Mon Feb 03 10:08:55 2020
      mtime = Mon Feb 03 10:09:03 2020
      interactive = 5
      Variable_List = PBS_O_LOGNAME=root,PBS_O_HOST=centos,PBS_O_MAIL=/var/spool/mail/arung,PBS_TZID=America/Los_Angeles
      euser = root
      egroup = root
      partition = P3

      % qmgr -c "l q R865"
      Queue R865
      queue_type = Execution
      total_jobs = 0
      state_count = Transit:0 Queued:0 Held:0 Waiting:0 Running:0 Exiting:0 Begun:0
      acl_user_enable = True
      acl_users = root@centos
      resources_max.ncpus = 2
      resources_available.ncpus = 2
      enabled = True
      started = False
      partition = P3

  • Once a reservation is confirmed and partition is assigned to it, it can not be re-confirmed or altered in any other partition.

  • Reservations (and their queues) confirmed by the default scheduler are marked under partition "pbs-default".

  • PBS assigns a default partition name "pbs-default" to all the reservations (and their queues) confirmed by the default scheduler. If an admin tries to assign a scheduler/queue/node partition name "pbs-default", qmgr command throws error - "Default partition name is not allowed".

Interface 9: Deleted

Interface 10: Fairshare

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