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Nandish Mehta

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Multi Threading and Turbo options in SPECTRE
Feb 24^th, 2011, 10:01pm

Hi friends,

I am using MMSIM 7.2 (with SPECTRE) for my simulations. My circuit has around 56 nodes but the simulations takes lot of time because of large .tran stop period required.

My questions is, when I use Turbo with multi-threading it reports me that multi threading is disabled as circuit is too small. I think I need atleast 500 or more nodes.

It seems with smaller nodes & longer .tran simulation time there is no way to speed up my simulation.

Can any one please comment on this? How do I make my .tran run faster without sacrificing accuracy.

Thanks
Nandish

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Geoffrey_Coram Senior Fellow Offline Posts: 1999 Massachusetts, USA	Re: Multi Threading and Turbo options in SPECTRE Reply #1 - Feb 25^th, 2011, 6:11am Do you need the full tran, or could you use envelope following?
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Nandish Mehta Junior Member Offline Posts: 22	Re: Multi Threading and Turbo options in SPECTRE Reply #2 - Feb 26^th, 2011, 12:30am Hi Geoffrey, Unfortunately I cannot do envelop following. I have to do full .tran. Can you please suggest any alternate? Regards Nandish
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Geoffrey_Coram

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Re: Multi Threading and Turbo options in SPECTRE
Reply #3 - Feb 28^th, 2011, 5:29am

There's some overhead involved in creating the various threads and splitting up the work; I guess Cadence has decided that one generally gets a *slower* simulation with multi-threading unless the circuit is "big enough."

Do you have access to APS? I think Cadence advertises that as having better multi-threading.

Do you need one long tran? Or are you computing the response to a long set of inputs, such that you could split it up into 10 simulations, each of which takes 1/10 of the set of input transitions?

I don't think I can give you any further suggestions without understanding why you need very accurate results for such a long transient.

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If at first you do succeed, STOP, raise your standards, and stop wasting your time.

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fom

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Re: Multi Threading and Turbo options in SPECTRE
Reply #4 - Mar 2^nd, 2011, 7:28pm

First, you can add 500 dummy silent nodes to force multithreading switch ON.
Second, you can use skippoint option to speed up your simulation. If skippoint is very large the simulation result can lost some short pulses. But actually simulator will catch this pulses and circuit behavior will be correct.

Frankly speaking I thougt only APS support multithreading.

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aThomas

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Re: Multi Threading and Turbo options in SPECTRE
Reply #5 - Apr 18^th, 2011, 10:46am

Just to clarify....

Spectre Turbo - multi threads only device models. matrix solving not multi-threaded

APS - Fully multi threads both models and matrix solving. Also even without multi-threading, APS in MMSIM10.1.1 has been enhanced for faster performance when running with single thread.

If you have access to APS, use it instead of Turbo.

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