Designer’s Guide Community

John O Donovan

Junior Member

Offline

Posts: 29
San Jose, CA

Re: Multi-thread Circuit Simulator
Reply #15 - Sep 25^th, 2007, 10:16pm

Hi,

On the subject of crashing, could you provide some more details, such as the version of Spectre used, when the crash occured, what type of models are being used, etc ... Multi-threading of device evaluation, while not simple, is not fundamentally very complicated, and should not lead to any crashes since by the time devices are being evaluated, all required memory is allocated, hence no memory related issue should exist.

John

Back to top

IP Logged

JoRobins

New Member

Offline

Give and it shall be
given unto you!

Posts: 6
San Diego, CA

Re: Multi-thread Circuit Simulator
Reply #16 - Sep 29^th, 2007, 7:58am

Andrew Beckett wrote on Aug 27^th, 2007, 1:52pm:

To reply to the original question, Spectre from Cadence has multithreading capability, both for device model evaluation, and also in the harmonic balance engine in SpectreRF.

Regards,

Andrew.

Just a quick comment on my experience with the multithreading option in spectre. Typically for a top level PLL sim transient sim (>500 devices?), a colleague and I saw a speedup of about 2x on a 4-core CPU machine using the multithread option. I remember that for extracting the max. benefit out of multithread sims, Cadence had some recommendations like not to have current probes inserted and such... The spectreRF shooting engine based pss does not use the multithread option which is a bummer.... I'm yet to warm up to the harmonic balance version...

Back to top

IP Logged

byang

Community Member

Offline

Posts: 46

Re: Multi-thread Circuit Simulator
Reply #17 - Sep 29^th, 2007, 11:56am

Hi, Jorobins,

2x speedup on 4-core computer is kind of low. This is especially true if device model evaluation of a simulator is slow. In that case, device model evaluation should benefit a lot from multi-threading. (Current probe can add more nodes in the circuit, which causes the circuit matrix to become bigger and slower to solve. Unfortunately matrix parallelization is much harder to do.)

The best next-generation multi-threaded circuit simulator should have:

* fast device model evaluation and yet high multi-threading efficiency

* efficient parallel matrix solver

which covered the two most important areas in circuit simulation: device model evaluation and matrix solving.

Baolin Yang, Ph.D.
Founder and President
Gemini Design Technology, Inc.
www.gemini-da.com

Back to top

IP Logged

IainC

New Member

Offline

Posts: 1

Re: Multi-thread Circuit Simulator
Reply #18 - Aug 8^th, 2008, 6:31am

I'm really quite doubtful that a mixed signal design could be simulated faster multi-threaded.

Given that it's transient you would likely lose as much time synchronising at each timepoint as you gained in parallel processing - not to mention the major headache you would have if the results of one process affected the (on-going) calculations handed to another thread. e.g. something in the circuit switches.

Not an expert in this by any means but I can't see for a typical design how this could be made to work.

Back to top

IP Logged

schehrazi Community Member Offline Posts: 45 University of CA, LA	Re: Multi-thread Circuit Simulator Reply #19 - Sep 9^th, 2009, 5:35pm On the same subject: http://www.cadence.com/Community/blogs/ii/archive/2009/07/31/dac-report-gpus-or-...
Back to top	IP Logged

ywguo Community Fellow Offline Posts: 943 Shanghai, PRC	Re: Multi-thread Circuit Simulator Reply #20 - Sep 12^th, 2009, 12:53am 4x speed up on 4-CPU computer for Corner Analysis in ADE.
Back to top	IP Logged

schehrazi Community Member Offline Posts: 45 University of CA, LA	Re: Multi-thread Circuit Simulator Reply #21 - Sep 12^th, 2009, 1:21am That's different though since the corner simulations are independent of each other. If one gets 4X speed up in transient simulation on a 4 CPU machine, that will be something.
Back to top	IP Logged

Andrew Beckett

Senior Fellow

Offline

Life, don't talk to
me about Life...

Posts: 1742
Bracknell, UK

Re: Multi-thread Circuit Simulator
Reply #22 - Jan 4^th, 2010, 1:09pm

I'd quite forgotten about this thread, and things have moved on a lot since it started.

Cadence's APS simulator (which is essentially a mode of spectre) parallelizes both the device evaluation and matrix solve, and does a number of other things to get large speed improvements without compromising accuracy; some of which is the result of having an improved matrix solver - so we see speed improvements even on single core. Don't want to make this a sales pitch, but if you're already using spectre and are unaware of APS, it's worth contacting Cadence to find out more. It's in use by a lot of happy users now...

It was introduced in MMSIM71, and in MMSIM72 APS is extended to most of the analyses in spectre, including the RF analyses.

Regards,

Andrew.

Back to top

IP Logged

schehrazi Community Member Offline Posts: 45 University of CA, LA	Re: Multi-thread Circuit Simulator Reply #23 - Jan 4^th, 2010, 1:26pm Thank you Andrew. I have heard of the APS but have never tried it. I will give it a try and will let you know of my experience if I have it installed.
Back to top	IP Logged