multitreading with asynchronous

7/28/2019 Multitreading with Asynchronous

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DSMThreads

PthreadsBIP/

TCP

Madeleine

Marcel(shallow binding)

Figure 1. Layering of Software Components

Table 1. Mapping TCP/IP onto Madeleine


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T0

fctT

fctT

T0

T0

fctT

T0

fctT

T0

T0

node 3

slave 2

node 2slave 1

CS

node 1master

CS

node 1master

CS

node 2slave 1

CS

node 3

slave 2dsm_exit

CS

CS

send a message

rsh $host program ... CS communication server

T main thread0

T thread that performs a user functionfct

program start

pthread_create

(function)

dsm_thread_create

dsm_thread_create

dsm_init dsm_init

dsm_init

dsm_init

dsm_exit

dsm_thread_create

dsm_thread_create

(function)

dsm_exit

dsm_exit

dsm_init

dsm_exit

dsm_init

dsm_exit

(a) Original Model (b) Modified Model

> program > dsmload program

Figure 2. Distributed Execution Models for DSM-Threads

4.1 Direct and Indirect Communication

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P1 P2

msg to T2

P1 P2

sending a message reception of a message notification of an user thread P 1/2 processes

T 1/2 user threads

CS communication server observes POC 1/2

POC x port/channel of a process/thread

msg to T1

POC2.1

T1 T2T2T1

POC1.1

POC2.2POC1.2

(a) Direct Reception of Messages on Distinct Ports/Channels (b) Indirect Message Reception via Demultiplexing on a Single Port/Channnel

T2CS

T1 msg to T2

CS T2

T1

msg to T1

POC2POC1

Figure 3. Connection Models for Message Passing

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4.2 MT-Safe Message Passing


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registerHandler( ReceiveMessage )

receive( buffer )

Handler

ReceiveMessage

process message basically

return

process message

suspends execution of the thread

msg available on the network

resume waiting thread

copy msg to buffer, etc.

Figure 4. Message Reception after Event Notification

while(!test( handle ))

handle := init( buffer )

sleep( x ms )

process message

wait x milliseconds; blocks thread;

other threads may become active

test != 0 msg available in buffer

Figure 5. Message Reception via Polling

4.3 Partial Message Processing

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CS communication server

receiving a message

actions of the CS

header, fixed size

for a page

temporary buffer

actual page

reads message header

allocates memory formessage body and storesit there

copies body (page) to

actual address

header, fixed size

actual page

reads message header

extracts page address

from header and

directly to actual address

copies body (page)

CS memorymemory

(b) ZeroCopy Overhead(a) Traditional Copy Overhead

CS

worker

Figure 6. Message Unpacking Models

5.1 Replacing Marcel

Table 2. Shallow Binding: Marcel to Pthreads

5.2 Adapting Madeleines BIP-Interface


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T

T: wait(c)

CSREQUESTCS

CS: signal(c)

T continues

DATA

ACK

sender receiver

ba

REQUEST

ACK

DATA

TCS

sender receiver

Figure 7. Models for Sending Large Messages under BIP

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Bsnd rcv

B

A

3 0

A Asnd rcv

B

3 0

Bsnd rcv

B

A

A Asnd rcv

B

3 30 0

2 03 1

0credits

backtoB

b

Bsnd rcv

B

A

A Asnd rcv

B

3 1 00credit

s

backtoA

2

1 03 2

da

Bsnd rcv

B

A

A Asnd rcv

B

2 30 1

backtoA

023 1

c

1credit

Figure 8. Credit Mechanism

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multitreading with asynchronous

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