Simulation of the Fresh BreezeStorage System

Xiaoxuan MengJack Dennis

MIT CSAIL University of Delaware

Funded by NSF HECURA Grant CCF-0937832

Project Goals

• Implement fine-grain management of tasks and memory.• Provide a base for cpability-based access control and security.• Support composability of arbitrary parallel program components.• Achieve high efficiency in operation.

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Computer Systems that:

The Fresh Breeze Memory Model

• Fan-out as large as 16

Data

Chunkse.g. 128 Bytes

Master

Chunk

• Write-Once then Read Only

Cycle-Free Heap Arrays as Trees of Chunks

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• Arrays: Three levels yields 4096 elements (longs)

Storage System Architecture

Execution System

Top Storage

Level

4

AD

Main Storage

Level

CUSU

SUAD CU

SU

SU

AD CUSU

SU

AD – Associative Directory

CU - Control Unit

SU – Storage Unit

Spawn and Join

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Master Task

spawn (n)

join_fetch Join

Worker 0 Worker n-1

join_update join_update

Spawned Tasks

Continuation Task

Spawn - Join Implementation

Results from

Spawned Tasks

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Join TicketJoin Data

Count/Limit

Continuation

Task

System for Simulation

L1P

MainMemory

Switch

Processors

40Up to 64IndependentStorage Units

EUs TSUs MSUs

L1P

Fresh Breeze Simulation

X-Bar Switch

EUs – Task Execution TSUs – CacheImplementation

MSUs – Main Storage Implementation

Cyclops TUs

The Dot Product

A

B

* Sum

A B

5 levels:Vector length =165 = 1,048,576

* +

scalar result

* *

Each Task:Dot Product of two16-element vectors:16 multiplies; 15 adds

Spawn – Join Programming

void DotProd ( a, b ) {join_init (16, Accumulate ( ) );for ( i = 0; i < 16; i++)

spawn_one ( i, DotProd ( a[i], b[i] )quit ();

}

void Accumulate ( ) {handle = join_fetch ();sum = 0;for ( j = 0; j < 16; j++ )

sum += handle [j];join_update ( sum );

}

Findings

• Using fine-grain tasks and a hardware scheduler can effectively distribute concurrent tasks over a large number of processors.

• Task stealing can achieve high utilization of many processors.

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Further Work

• Model a Three-Level Storage System: L1, L2, Main.• Task distribution to exploit data locality.• Further benchmark applications for testing: MM, FFT, LUD.• FunJava Compiler: DFG transformations and code

generation.

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