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Volume: 12, Issue: 9, Fri Dec  1 10:23:49 EST 1989

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| TODAY'S TOPICS |
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(1) Reducing Time Warp Overhead
(2) Call for Papers: DEVS & Advanced Modelling
(3) Time Warp
(4) Knowledge Based Simulation of Circuits

* Moderator: Paul Fishwick, Univ. of Florida
* Send topical mail to: simulation@bikini.cis.ufl.edu OR
  post to comp.simulation via USENET
* Archives available via FTP to bikini.cis.ufl.edu, login as
  'ftp', use your last name as the password, change
  directory to pub/simdigest.
* Simulation Tools available by doing above and changing the
  directory to pub/simdigest/tools.



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Date: Wed, 22 Nov 89 17:12:11 -0800
From: liny@cs.washington.edu (Yi-Bing Lin)
Return-Path: <liny>
To: fishwick@bikini.cis.ufl.edu
Subject: Reducing the state saving overhead of Time Warp

The following  technical report (TR 89-09-04) can be requested via
e-mail: tech-report@june.cs.washington.edu


THE OPTIMAL CHECKPOINT INTERVAL IN TIME WARP PARALLEL SIMULATION

	     Yi-Bing Lin and Edward D. Lazowska 
       Department of Computer Science and Engineering
		  University of Washington
	 	      Seattle, WA 98195

			   ABSTRACT

The Time Warp mechanism is the most common ``optimistic'' parallel
simulation protocol.  A process executes every message as soon as it
arrives.  If a message with a smaller timestamp subsequently arrives,
the process rolls back its state to the time of the earlier message
and re-executes from that point.

Clearly, the state of each process must be saved (checkpointed)
regularly in case rollback is necessary.  Although most existing Time
Warp implementations checkpoint after every state transition, this is
not necessary, and the checkpoint interval is in reality a tuning
parameter of the simulation.

This paper shows how to derive the optimal frequency of checkpointing
in Time Warp simulation. We express the optimal checkpoint interval as
a function of the average rollback distance, the average state saving
overhead, the ratio of the total number of executed messages to the
total number of undone messages, and the average cost of a simulation
step.  The result is consistent with the following intuition: A large
checkpoint interval should be chosen if and only if the state saving
overhead is large, and/or a large number of events are executed, on
the average, between two consecutive rollbacks.



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Date: Thu, 30 Nov 89 13:58 CDT
From: TKIM@kuhub.cc.ukans.edu
Subject: Ad for a call for papers
To: fishwick@fish.cis.ufl.edu
X-Vms-To: @fish

Call for papers
     
SIMULATION DIGEST's Special issue on 
"The DEVS Formalism and Advanced Modelling Simulation Methodology"
     
Authors are invited to submit abstracts of papers describing recent
advances on all aspects of the DEVS (Discrete Event System Specification)
formalism. These may include simulation environments implementing the
formalism and applications of the environments to modelling and simulation
of various discrete event systems.
     
Abstracts should be not more than two double-spaced pages.
Abstracts must be received not later than Jan 15 of 1990.
Accepted papers will be determined by Jan 31 of 1990.  Accepted
full papers will be due by March 15 of 1990 in order to be published 
in the special issue of the SIMULATION DIGEST for 1990.
     
Mail abstracts to:
     
Prof. Tag Gon Kim
Dept of Electrical and Computer Engineering
The University of Kansas
Lawrence, KS 66045
e-mail: "tkim@ukanvax"
(ph) 914-864-7740
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From: "cp.jobling eleceng staff" <eechris%pyramid.swansea.ac.uk@NSFnet-Relay.AC.UK>
Date: Thu, 30 Nov 89 20:40:18 GMT
To: simulation@bikini.cis.ufl.edu

Hi,

I've just become aware that 'time-warp' may be the answer to
something I want to do in object oriented techniques for
continuous systems simulation. I am therefore looking
for pointers to key references, preferably those that
are easy to get hold of. Is there anybody out there
who could mail me a bibliography?

The only references I've come across so far are a couple of
tech-reports from the Rand Corporation. Maybe someone from
that body could tell me how to get hold of these?

Thanks
	Chris
========================================================================
Chris Jobling, Department of Electrical and Electronic Engineering,
University College, Swansea, Singleton Park, Swansea SA2 8PP, UK
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Phone:	+44-792-295580	Fax:	+44-792-295532	Telex:	485358
email:	JANET:			eechris@uk.ac.swan.pyr
	Internet		eechris%pyr.swan.ac.uk@cunyvm.cuny.edu
	Earn/Bitnet		eechris%pyr.swan.ac.uk@UKACRL
	UUCP			eechris%pyr.swan.ac.uk@ukc.uucp
	EAN			eechris@pyr.swan.ac.uk
========================================================================



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From: Klaus Milzner <milzner@unidocv.informatik.uni-dortmund.de>
Date: Fri, 1 Dec 89 14:44:55 +0100
To: simulation@bikini.cis.ufl.edu

Hi out there !

I currently do some research in the area of circuit specific, knowledge 
based simulation support. The aim is the realization of a simulation 
assistant capable of automatically characterizing certain classes of 
circuits and providing estimations of the simulation and design results.

Though simulation is a central aspect of nearly every design cycle, 
surprisingly little attention seems to be payed to this topic in the 
past. To complete my studies of literature, i'm urgently looking for
any pointers, references etc. concerning this field.

ANY comments are appreciated...:-)

Thanks in advance,
                    Klaus
 
PS: Are there any information about NECTAR from UCB available ?

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|   Klaus Milzner          University of Dortmund     Lehrstuhl Informatik 1  | 
|   milzner@unidocv.uucp                                                      |
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