( ESNUG 387 Item 13 ) -------------------------------------------- [01/23/02]
Subject: ( ESNUG 385 #14 ) Get The Absolute Minimum PLI With Cadence NC-SIM
> By running VCS with only the Signalscan PLI compiled in VCS (but not used),
> I got a speed-up of 8 to 10 percent on a 3 Mgate RTL design and close to
> 20 percent on a 500 kgate RTL design.
>
> By not compiling in any PLI routines I got a speed-up of 42 to 48 percent
> on both my small and large design.
>
> - Anders Nordstrom
> Nortel Networks, Ltd. Ottawa Canada
From: "Kathleen Meade" <meade@cadence.com>
Hello John,
Thought I'd respond to ESNUG 385 #14 and explain how to use the options in
NC-Sim to limit access control for optimal performance but allow access
that is required for Tcl scripts and PLI applications.
In general, NC-Sim runs with minimal debugging capability. To access signals,
modules and lines of code during simulation, global options can be applied
for read, write and connectivity access:
% ncelab -access r|w|c <other_options>
% ncverilog +access+[rwc] <other_options>
If you want to allow/limit access for specific objects, modules or instances,
you create an access file and specify access for those objects. Then you
use the -afile option when running the elaborator.
% ncelab -afile access.txt test.top <other_options>
If you know that your simulation run will require some access for Tcl, PLI
or probing that aren't known in advance (i.e. the PLI calls or probes that
aren't in your code) but you don't know which objects are affected, you can
automatically generate an access file. To do this, use the -genafile option
when you invoke the elaborator. When you simulate, the objects that are
accessed by Tcl or PLI applications are monitored along with the types of
access required for each object, and when you exit the simulation, an access
file is created. For example:
% ncelab -genafile access.txt test.top <other_options>
% ncsim test.top <other options>
After the simulation completes, the access.txt file is generated. You then
use the -afile option in future runs to control access (like above):
% ncelab -afile access.txt test.top <other_options>
If you are using ncverilog, the command line options are:
+ncgenafile+access_filename and +ncafile+access_filename.
I hope this helps your readers!
- Kathleen Meade
Cadence Design Systems Atlanta, GA
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