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Visitor moreaub
Visitor
10,125 Views
Registered: ‎09-10-2013

Modelsim - changing resolution during simulation

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Hi,

 

I want to know if it is possible with Modelsim to change the simulation resolution at strategic moments to speed up a very long simulation ? Indeed, most of my simulation doesn't have to be very accurate (1 ns resolution would be enough), but short parts of the simulation have to be accurate at 1 ps.

So for the moment, I run the simulation at 1 ps... and I wait for a long time.

 

Thanks in advance for your suggestions !

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Xilinx Employee
Xilinx Employee
18,719 Views
Registered: ‎05-07-2015

Re: Modelsim - changing resolution during simulation

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Hi @moreaub

 

It is suggested practice that you should choose the coarsest resolution limit possible that does not result in undesired rounding of your delays. In your case it seems to be 1ps.

Modelsim has a 64bit unsigned integer for keeping simulation time . so even with 1 ps  resolution, a simulation can run 2^64 *10^-12  seconds (> 5000 hrs).

As mentioned earlier, in event driven simulators,  the simulator resolution per se does not take much toll on simulator performance.



Thanks
Bharath
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Xilinx Employee
Xilinx Employee
10,119 Views
Registered: ‎05-07-2015

Re: Modelsim - changing resolution during simulation

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hi moreaub,


There is no simulator performance gain by using coarser resolution with the Xilinx simulation models. Because much simulation time is spent in delta cycles, and delta cycles are not affected by simulator resolution, no significant simulation performance can be obtained


Thanks
Bharath
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Xilinx Employee
Xilinx Employee
10,079 Views
Registered: ‎10-24-2013

Re: Modelsim - changing resolution during simulation

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Hi @moreaub

 

MentorGraphics forums is the correct place for this topic. Please get in touch with them.

Thanks,Vijay
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Xilinx Employee
Xilinx Employee
18,720 Views
Registered: ‎05-07-2015

Re: Modelsim - changing resolution during simulation

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Hi @moreaub

 

It is suggested practice that you should choose the coarsest resolution limit possible that does not result in undesired rounding of your delays. In your case it seems to be 1ps.

Modelsim has a 64bit unsigned integer for keeping simulation time . so even with 1 ps  resolution, a simulation can run 2^64 *10^-12  seconds (> 5000 hrs).

As mentioned earlier, in event driven simulators,  the simulator resolution per se does not take much toll on simulator performance.



Thanks
Bharath
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Give Kudos to a post which you think is helpful.
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