Config view sweeps - time of netlist creation for all corners in a multi-corner simu;ation

Hello cadence,

In Assembler (ICADV12.30.ISR15).

When using config view sweeps in a multi corner simulation, say in a 128 corner simulation as an extreme case, when do ALL the 128 netlists get created ?

  1)  All  start of the simulation ?  or

  2) As the simulation progresses ? In other words when the simulation gets around to each corner.

The reason why I ask is because, for a top-level block where many designers are poking around all the time and the simulation can span a few days, the netlist that will be created at the time of the simulation launch may not be the same as the one created a few days later. Obviously this would render the simulation results useless.  

If such is the case, are the settings or environment variables that can force the netlist creation of ALL 128 corners at the time of the simulation launch ?

Regards,

Frank

Hi Frank,

You can put:

adexl.simulation ignoreDesignChangesDuringRun boolean t

into your ~/.cdsenv file or

envSetVal("adexl.simulation" "ignoreDesignChangesDuringRun" 'boolean t)

in your .cdsinit. Note that typing the above into the CIW won't be sufficient because it has to be picked up by the ICRP too.

This does come with a penalty - it has to spend more time creating netlists up front which could have been done in parallel otherwise. For anyone using design management to version control their design, I tend to suggest running long simulations in a separate workspace than the one where you're editing the design so that you can be isolated from changes in your workspace (of course, it means that all the reference libraries that could change are also versioned in your workspace so that you don't see live edits). If you do this, then you don't need to resort to ignoreDesignChangesDuringRun.

Regards,

Andrew

Thanks Andrew. That was exactly what I was looking for.

As for working in a separate workspace for long simulations ... you hit the nail right on the head! I can't do that all the time because the reference libraries are not always versioned in my workarea.

Frank  

Hello Andrew,

When setting ignoreDesignChangesDuringRun to t, and running a simulation using a config sweep variable the following message is displayed:

  You are running a simulation with config variables and
  'ignoreDesignChangesDuringRun' or 'singleNetlistForAllPoints'
  variables set to t.
  ADE Assembler will ignore the settings for the variables.
  Any modifications to the design during the run will be taken into
  consideration and seperate netlists will be generated for all
  the points.

Furthermore as to confirm the message, the simulation generates the corner netlists as the simulation progresses. It does not generate ALL the corner netlists at simulation launch.

Comments ?

Thank you. Frank

Hi Frank,

There are technical reasons for this, which is why we tell you that it's not supported. The ignoreDesignChangesDuringRun was a later addition and doesn't directly fit with the underlying infrastructure which means that not all sweep situations are supported. There is some architectural work going on which will hopefully mean that ignoreDesignChangesDuringRun will ultimately be unnecessary, but I can't say when that will be available.

Regards,

Andrew.