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Simulation CPU cores usage

AllenD

Hi Friends,

Can I please ask a question concerning simulation CPU cores usage. 

When I was using ADS on a Windows PC for simulation, the software will automatically use all the cores and the CPU usage is close to 95%. 

However, now I am using CADENCE IC 617 and MMSIM151 on a Linux machine with 10 cores CPU (20 threads). The simulation setup is like this:

ADE L --> Setup --> High-Performance Simulation Options. Then I click APS. choose Error Preset: DO not override; Use ++aps; Multi_Threading Manual #Threads: 20  (0-19)

But when I try to simulate, the CPU usage is about 40%. Though this is way better when I chose Spectre instead of APS to simulate(that's 5% CPU usage, due to only one thread is working.) 

Can anyone help me? How can I setup the software to use all the CPU power to speed up the simulation?

Thanks

Allen.

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  • Allen,

    How big is your circuit? Perhaps you can post the "Circuit Inventory" section of the log file. It has to be pretty large (probably hundreds of thousands of devices) to benefit from that number of cores. There's something known as Amdahl's Law which is quite useful to understand here - adding more parallel resource does not necessarily mean you speed up because there are some things that cannot be parallelised or the cost of managing the threads exceeds the benefit gained.

    Regards,

    Andrew.

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  • Allen,

    How big is your circuit? Perhaps you can post the "Circuit Inventory" section of the log file. It has to be pretty large (probably hundreds of thousands of devices) to benefit from that number of cores. There's something known as Amdahl's Law which is quite useful to understand here - adding more parallel resource does not necessarily mean you speed up because there are some things that cannot be parallelised or the cost of managing the threads exceeds the benefit gained.

    Regards,

    Andrew.

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