A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities

Status Presentation2011-03-18

Matias Mora Kleinmmora@csrg.inf.utfsm.cl

UTFSM Computer Systems Research GroupAtacama Large Millimeter/submillimeter Array

Advisor: Dr. Mauricio Solar (UTFSM)Co-Advisor: Dr. Víctor Parada (USACH)

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 22

Problem Description

ObservationProposals

ObservationProposals

SchedulingPlan

SchedulingPlan

ExternalFactorsExternalFactors

ExecutionPrioritiesExecutionPriorities

Re-SchedulingRe-Scheduling

“Maximize the scientificthroughput of the

telescope” [Sessoms09]

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 33

Problem Description

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 44

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 withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 55

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 withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 66

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 ~10.000 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 withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 77

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 withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 88

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 withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 99

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 withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1010

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 withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1111

Validation

Algorithm implementation to verify the model ALMA Scheduling simulator (?) External reviews: ALMA Software Engineers and

Array Operators

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1212

Working Plan

Phase 1: State of the Art, technical research June – November 2009 (Done)(Done)

Phase 2: Problem description and modeling September 2010 – January 2011 (Done)(Done)

Phase 3: Algorithm design and implementation February – March 2011 (In progress)(In progress)

Phase 4: Implementation validation April – May 2011 (Pending)(Pending)

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1313

Working style (CSRG)

Overall project discussion and notes: TWiki https://csrg.inf.utfsm.cl/twiki4/bin/view/ACS/MatiasMoraMasterThesis

https://csrg.inf.utfsm.cl/twiki4/bin/view/ACS/DynamicPrioritiesModelDiscussion

https://csrg.inf.utfsm.cl/twiki4/bin/view/ACS/MatiasMoraThesisWorklog

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 E-mail

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1414

Current Status

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1515

Schematic description

Projects and Scheduling Blocks

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1616

Schematic description

Overall scheduling process

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1717

Schematic description

Short and long-term queues generation

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1818

Mathematical model

Static parameters

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 1919

Mathematical model

Dynamic variables (1)

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 2020

Mathematical model

Dynamic variables (2)

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 2121

Mathematical model

Objective functions Maximize the scientific value (grade) of completed

projects.

Minimize the array's idle time (maximize busy time).

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 2222

Mathematical model

Search space discussion Long-term queue Short-term queue

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 2323

Algorithm implementation

A Scheduling Algorithm withA Scheduling Algorithm withDynamic PrioritiesDynamic Priorities 2424

To be continued ...