distributed simulation in spectre RF.

[amitbhaiji]

simulation time spectre rf machin

can any one suggest me how to run a distributed simulation in spectre.
Regards
Amit

 

[eda4you]

cadence distributed simulation spectre

can any one suggest me how to run a distributed simulation in spectre.
Regards
Amit

Do you need for vhld/verilog simulation or analog simulation. For digital simulation there is as Ican remind something like load sharing facility. For mixed-signal there is also some tool which I can't remember (one machine simulates the vhdl part, one the analog, etc..). Also for corners there is a tool for distributing simulation.


However, I'm also interested if there is a cadence tool which supports distributed simulation of one analog design.

 

[HCM_bucat]

how to run distributed simulation cadence

I don't think that Spectre RF support Multithread simulation. Hspice does

 

[eda4you]

spectre distributed simulation howto

I don't think that Spectre RF support Multithread simulation. Hspice does

Hi HCM_bucat!

Could you explain the multithread simulation in more detail? Does this implement that ONE analog design can be distributed to several machines --> parallel simulation or that one design can be splitted into several ones and than cosimulated on several machine. I would be very interested about this.

Thanks

 

[HCM_bucat]

spectre multithread

Yes, they are all parallel operation. Distribution means divide the work to different system. Multithreading means sdividing the work to different CPUs ( remember nowaday most of the workstation is a multi-CPU machine).
Here is the excerp from Hspice Manual:
Improving Simulation Performance Using Multithreading
Star-Hspice simulations involve both model evaluations and matrix solutions. Running model evaluations concurrently on multiple CPUs using multithreading can significantly improve simulation performance. In most cases, the model evaluation will dominate. To determine how much time is spent in model evaluation and solving, specify .option acct = 2 in the netlist. Using multithreading results in faster simulations with no loss of accuracy.

Multithreaded (MT) Star-Hspice is supported on Sun Solaris 2.5.1 (SunOS 5.5.1) and on Windows NT as a prerelease version using win32 threads.

Running Star-Hspice-MT
You can run Star-Hspice-MT using the syntax described below.

Sun Solaris Platform
Enter on the command line:

hspice -mt #num -i input_filename -o output_filename

Windows NT Platform
Under the Windows NT DOS prompt type:

hsp_mt -mt #num -i input_filename -o output_filename


--------------------------------------------------------------------------------
NOTE: If the #num is omitted, the number of threads will be set to the number of online CPUs.
If you omit the -o output_file option, the result will be printed to the standard output.
--------------------------------------------------------------------------------

Under Windows NT explorer:

1. Double click the hsp_mt application icon.

2. Select the File/Simulate button to select the input netlist file.

In Windows, the program will automatically detect and use the number of online CPUs.

Under the Avant! HSPUI interface:

1. Select the correct version of hsp_mt.exe in the Version Combo Box.

2. Select the correct number of processors in the MT Option Box.

3. Click the Open button to select the input netlist file.

4. Click the Simulate button to start the simulation.

Performance Improvement Estimations
For multithreaded Star-Hspice, the CPU time is:

Tmt = Tserial + Tparallel/Ncpu + Toverhead

where:

Tserial Represents the Star-Hspice calculations that are not threaded

Tparallel Represents the threaded Star-Hspice calculations

Ncpu The number of CPUs used. Toverhead is the overhead from multithreading. Typically, this represents a small fraction of the total run time.

For example, for a 151-stage nand ring oscillator using LEVEL 49, Tparallel is about 80% of T1cpu (the CPU time associated with a single CPU), if you run with two threads on a multi-CPU machine. Ideally, assuming Toverhead = 0 , you can achieve a speedup of:

T1cpu/(0.2T1cpu + 0.8T1cpu/2cpus) = 1.67

For six CPUs the speedup is:

T1cpu/(0.2T1cpu + 0.8T1cpu/6cpus) = 3.0

The typical value of Tparallel is 0.6 to 0.7 for moderate to large circ

 

[eda4you]

hspice mt

Puhh!

That's absolut cool. I hope we have a license in our company for mt. Do you have some experience with this tool?

 

[Teddy]

lets suppose that you mean distributed simulations started from analog artist environment.
If this is the case you need:
a) to add all the possible servers and login info to the rhosts or etc/hosts files to make sure that you can rlogin to those machines without always putting in login and password.
b) create queue config file which looks like this:
queue_name number_of_machines_inthis_queue (ie. queue1 3)
machine_name1 #processes_to_run_on_it_at_same_time (ie: srv1 3)
machine_name2 #processes_to_run_on_it_at_same_time (ie: srv2 3)
machine_name3 #processes_to_run_on_it_at_same_time (ie: srv3 3)
- this is generaly how the file looks like - more in cadence docs
c) need to start cdsqmgr
- I recommend quit cadence and logout/in
- to start it: cdsqmgr cdsqueue_config_file_name
d) restart cadence
e) in analog artist : Setup -> Simulator/Directory/Host
change host mode to distribute and hit check setup - all items in check setup log must be "OK"
f) ok in simulator/directory/host
Now when you run simulation you will have to name the run and some other stuff.
to view results you need to use result browser or any extrernal viewer

have fun!

 

[Teddy]

Also - multithread works (depending on version of cadence) but just for MOS devices (BSIM3 and higher) and at least 256 active devices.
It does not give 2x3x etc speed up though. If you need speed up on 1 processor use Analog Options -> accelerated models (MOS ONLY) or any of the "speed" buttons (latest version of CDS)
You go down with precision a bit !

 

[Teddy]

Also - multithread works (depending on version of cadence) but just for MOS devices (BSIM3 and higher) and at least 256 active devices.
It does not give 2x3x etc speed up though. If you need speed up on 1 processor use Analog Options -> accelerated models (MOS ONLY) or any of the "speed" buttons (latest version of CDS)
You go down with precision a bit !