A Scheduling Algorithm with Dynamic Priorities Status Presentation Matias Mora Klein UTFSM Computer Systems Research Group Atacama Large Millimeter/submillimeter Array Advisor: Dr. Mauricio Solar (UTFSM)‏ ‏Co-Advisor: Dr. Víctor Parada (USACH)

A Scheduling Algorithm with Dynamic Priorities 2 Problem Description Observation Proposals Observation Proposals Scheduling Plan Scheduling Plan External Factors External Factors Execution Priorities Execution Priorities Re-Scheduling “Maximize the scientific throughput of the telescope” [Sessoms09]

A Scheduling Algorithm with Dynamic Priorities 3 Problem Description

A Scheduling Algorithm with Dynamic Priorities 4 State of the Art The (dynamic) scheduling problem Basic “job shop” problem Dynamic “on-line” approach (CSP) Astronomical observations problem Proposal → Observing time → Observation block(s) Long-term plan:  source visibility, sky brightness Short-term plan:  atmospheric conditions, technical failure

A Scheduling Algorithm with Dynamic Priorities 5 State of the Art: Current Approaches Hubble Space Telescope (HST) Zweben, et al. (1994), Muscettola, et al. (1996) Very Large Telescope (VLT) Johnston (1988), Silva (2002) Subaru Telescope Sasaki, et al. (2000) Gemini Observatory Puxley (1997) Stratospheric Observatory for Infrared Astronomy (SOFIA) Frank (2006) Green Bank Telescope (GBT) Clark, et al. (2009), O'Neil, et al. (2009), Balser, et al. (2009), Sessoms, et al. (2009) Hubble Space Telescope  SPIKE (1987)  CSP  Trial assignment heuristic (min-conflicts times)  Repair heuristic (neural network)  De-conflict (priority selection) Green Bank Telescope  Dynamic Scheduling System (2008)  Scoring algorithm  Sudoku-solver (fixed, windowed sessions)  Knapsack algorithm (remaining time intervals)

A Scheduling Algorithm with Dynamic Priorities 6 ALMA Scheduling Subsystem 66 antennas operating as one or more array(s) Execute interactive / dynamic scheduling blocks Operate “exclusively” in service mode Performance requirements: Handle ~ SBs per period (12 months) Rescheduling process <<1/2 SB length (~30 min.) Currently: Construction phase, Early Science (2011/2012) with very basic DSA

A Scheduling Algorithm with Dynamic Priorities 7 Hypothesis It is possible to model the scheduling problem of observing proposals with dynamic priorities, for a radio telescope array(s), and generate feasible and sufficiently fast solutions.

A Scheduling Algorithm with Dynamic Priorities 8 General Goals Create a mathematical model for a scheduling system with dynamic priorities, and extend it to the ALMA Scheduling problem. Apply an algorithm to one of the identified instances to validate the model.

A Scheduling Algorithm with Dynamic Priorities 9 Specific Objectives Design a model for the dynamic priorities scheduling problem. Use that model to be applied to the ALMA Scheduling problem. Characterize instances of the ALMA Scheduling problem, and identify one suitable for a relatively easy resolution. Develop an algorithm for the identified instance. Evaluate the algorithm's performance, and compare it to the ALMA Scheduling performance requirements.

A Scheduling Algorithm with Dynamic Priorities 10 Expected Results A model for the dynamic priorities scheduling problem, applied to the ALMA Scheduling problem. An implemented algorithm for one of the identified instances. Test results obtained by running the implemented algorithm, which are expected to comply with the performance requirements.

A Scheduling Algorithm with Dynamic Priorities 11 Validation Algorithm implementation to verify the model ALMA Scheduling simulator (?) External reviews: ALMA Software Engineers and Array Operators

A Scheduling Algorithm with Dynamic Priorities 12 Working Plan Phase 1: State of the Art, technical research (Done) June – November 2009 (Done) Phase 2: Problem description and modeling (Done) September 2010 – January 2011 (Done) Phase 3: Algorithm design and implementation (In progress) February – March 2011 (In progress) Phase 4: Implementation validation (Pending) April – May 2011 (Pending)

A Scheduling Algorithm with Dynamic Priorities 13 Working style (CSRG) Overall project discussion and notes: TWiki Document editing: LaTeX Development environment: GNU/Linux Development IDE: Eclipse Docs + code version control: Subversion (SVN) svn co csrg.inf.utfsm.cl/repos/docs/scheduling-thesis/ Advisor coordination: Meetings and

A Scheduling Algorithm with Dynamic Priorities 14 Current Status

A Scheduling Algorithm with Dynamic Priorities 15 Schematic description Projects and Scheduling Blocks

A Scheduling Algorithm with Dynamic Priorities 16 Schematic description Overall scheduling process

A Scheduling Algorithm with Dynamic Priorities 17 Schematic description Short and long-term queues generation

A Scheduling Algorithm with Dynamic Priorities 18 Mathematical model Static parameters

A Scheduling Algorithm with Dynamic Priorities 19 Mathematical model Dynamic variables (1)

A Scheduling Algorithm with Dynamic Priorities 20 Mathematical model Dynamic variables (2)

A Scheduling Algorithm with Dynamic Priorities 21 Mathematical model Objective functions Maximize the scientific value (grade) of completed projects. Minimize the array's idle time (maximize busy time).

A Scheduling Algorithm with Dynamic Priorities 22 Mathematical model Search space discussion Long-term queue Short-term queue

A Scheduling Algorithm with Dynamic Priorities 23 Algorithm implementation

A Scheduling Algorithm with Dynamic Priorities 24 To be continued...