Improve performance of large simulations on Sun/Solaris

Starting with the ModelSim 5.5b you can improve simulation performance on Sun/Solaris by enabling shared memory. Up to a 2x improvement has been seen in large Verilog gate-level simulations, though the feature should speed up any simulation that consumes a large amount of memory.

Follow these steps to use the feature:

1. Enable a large shared memory segment by adding the following line to the /etc/system file:

set shmsys:shminfo_shmmax=0xffffffff 

2. Reboot your machine.
3. Immediately after the machine has been rebooted, run the program vshminit (found in the modeltech tree). The program takes a single parameter which is the amount of memory in megabytes to reserve for use by the simulator. For example, running vshminit like this:

<modeltech-tree>/sunos5/vshminit 700 

would reserve 700mb of space for use by the simulator. The next time you run the simulator it will automatically detect the reserved memory and use it.

Important: vshminit must be run immediately after you reboot the machine. (You might want to add the program to the system startup scripts.) There may be no performance benefit if you don't run it immediately after reboot.

The amount of memory you supply as a parameter to vshminit depends on the configuration of your system. Typically you might want to reserve 50-80% of the system memory for the simulator, depending on whether the machine is multi-use or is dedicated to running simulations.

To free the memory reserved by vshminit, execute the following command:

/bin/ipcrm -M 0x10761364 

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