BOINC Workshop 10

BOINC Workshop 10

Hien Nguyen, Eshwar Rohit

University of Houston

Supervisors:

Dr. Jaspal Subhlok

University of Houston

Dr. David P. Anderson

SSL – U.C, Berkeley

Enabling interprocess communication for BOINC applications

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RESEARCH GOAL

Hien Nguyen University of Houston

•Enable BOINC to efficiently support apps that require interprocess communication.

Goals: Easier programming for communicating applicationsReduce execution time (not increase throughput)

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Example Applications


REMD Protein Folding applicationEach process runs a standard molecular simulation at different temperature

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P1 P2 P3 P4 P5 P6 P7 P8

STEP-1

STEP-2

STEP-3

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Example Applications


Or many other applications:

Differential equation solvers (grid) (synchronous)Game playing with alpha/beta pruning (asynchronous)Search application.…..

Suitable applications: moderate amount of communication.

Synchronization point

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DIFFICULTIES


Job execution

Fast host

Slow host

X

X

Slow down overall execution speed

X

XWorse as number of

host increases

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OUTLINE


1. Volpex Dataspace Overview• IPC for volunteer environment

2. Integration With BOINC• Process management• Host selection

3. Future and Related Work

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Volpex Dataspace


•Dataspace: global shared space that processes can use for information exchange without a temporal or spatial coupling.

Volpex Dataspace Server

Put(ABC, 800)

Get(ABC,?) (800)

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Volpex Dataspace – Fault Tolerance


Put(ABC, 800)

Get(ABC,?) (800)

replicated

X

Volpex DSS is designed to support redundant Put/Get operations unlike Linda & variants

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Volpex Dataspace


•Why centralized? Scale issues

•But: firewalls, no incoming connections

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INTEGRATION WITH BOINC


•Mechanics: Process managementSimultaneous process startingFault toleranceCheckpoint/restart

•Policy: Host selection.

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Job execution scheme


X

BOINC Scheduler


Get work

Put data item

Get data item

Get checkpoint

Put checkpoint

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PROCESSES MANAGEMENT


•Simultaneous process starting:All processes start computation together: reduce wasted resources because processes will have to wait for eachothers.

Volpex jobs have highest (infinite) priority: uninterruptible by other jobs.

While waiting for all processes of a Volpex job to be ready: host can do other finite priority volunteer jobs.

Use of boinc_temporary_exit()

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•Fault tolerance

Dead instance spotted by heartbeat mechanism: process instances regularly send heartbeat to Volpex DSS.

BOINC scheduler recruits a new volunteer host to replace the dead one.

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•Hot spare policy: BOINC Scheduler


XFast replacement

Hot spare group

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•Checkpointing:

Process instance commits and uploads checkpoints to Volpex DSS (only stores latest checkpoint for each process).

Restarted process instance requests checkpoint from Volpex DSS.

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HOST SELECTION


•Volpex job: consists of processes that form a job, submitted by scientist.•Has requirements on:

DeadlineNumber of processes

•Has estimates of:Total flops per process.Flops between 2 consecutive checkpoints.Memory usage, disk usage

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HOST SELECTION POLICY


Criteria for selecting volunteer hosts to assign to a Volpex job: Speed and Availability.

Availability: the interval that a host is available w/o interruption (BOINC client allowed to compute).

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HOST SELECTION POLICY


Job’s minimum requirements:

•Minimum speed : Fast enough to meet job’s deadlineMin speed = Total flops / Deadline

•Minimum expected availability : host is continuously available for x hours to commit at least 1 checkpoint.

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Evaluate Host's Availability


•We want to predict host's length of availability interval.

•Method based on : Exploiting Non-Dedicated Resources for Cloud Computing Artur Andrzejak, Derrick Kondo, David P. Anderson. (NOMS10)

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Last value predictor: simplistic predictor which uses the availability value in the last hourly interval before prediction as the prediction of availability for the next x hours interval.

Combined with ranking hosts by predictability: number availability changes per week.

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In essence: select hosts which change availability very rarely.

A process assigned to a host with high predictability does not necessarily need to be replicated.

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IMPLEMENTATION STATUS


•Volpex utilities: for scientists to submit, abort or query status of a Volpex job.

•Modified BOINC scheduler: includes host selection for Volpex job.

•Modified Volpex DSS: handling new type of requests.

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IMPLEMENTATION STATUS


BOINC Server

submit job specs

Database

Create job & WU


X

Hot spare group

Scheduler request

Scheduler reply

dynamically create result from WU

BOINC Scheduler

heartbeat

checkpoint

request procID

get procID

procID of failed instance

replacement

Scientist

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FUTURE WORK


Experiment and evaluate with different degrees of freedom:

•Number of processes 10-1M•Communication pattern (local/global, synch/asynch)•Size and frequency of communication

Goal: study (via live experiment or simulation) the performance of Volpex/BOINC over this space

Application: Eratosthenes, REMD Protein Folding

Enhance host selection policy

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OTHER WORK


Volpex MPI: •An MPI library designed for executing parallel applications in volunteer environment.•Direct communication between processes.•Key Features

Controlled redundancy Receiver based direct communication Distributed sender based logging

More detail: “VolpexMPI: an MPI Library for Execution of Parallel Applications on Volatile Nodes” by Troy LeBlanc, Rakhi Anand, Edgar Gabriel, and Jaspal Subhlok.

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If you have application?


We would be happy to cooperate with you.

Our team contacts:•Dr. Jaspal Subhlok: [email protected]•Dr. David Anderson: [email protected]•Dr. Edgar Gabriel: [email protected]•Hien Nguyen: [email protected]•Eshwar Rohit: [email protected]•Rakhi Anand: [email protected]

Our Website: http://www2.cs.uh.edu/~jsteach/volpex/index.htm

Documents

BOINC Workshop 10