a scheduling algorithm with dynamic priorities status presentation 2011-03-18 matias mora klein...

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)

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Problem Description

ObservationProposals

ObservationProposals

SchedulingPlan

SchedulingPlan

ExternalFactorsExternalFactors

ExecutionPrioritiesExecutionPriorities

Re-SchedulingRe-Scheduling

“Maximize the scientificthroughput of the

telescope” [Sessoms09]

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Problem Description

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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

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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)

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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

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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.

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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.

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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.

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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.

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Validation

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

Array Operators

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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)

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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

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Current Status

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Schematic description

Projects and Scheduling Blocks

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Schematic description

Overall scheduling process

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Schematic description

Short and long-term queues generation

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Mathematical model

Static parameters

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Mathematical model

Dynamic variables (1)

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Mathematical model

Dynamic variables (2)

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Mathematical model

Objective functions Maximize the scientific value (grade) of completed

projects.

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

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Mathematical model

Search space discussion Long-term queue Short-term queue

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Algorithm implementation

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To be continued ...