( ESNUG 377 Item 18 ) ------------------------------------------- [09/19/01]
From: David Wang <wang@ati.com>
Subject: Two Users Question PrimeTime On Its Interface Logic Models (ILMs)
John,
Has anyone used PrimeTime's new ILM capability? I'm interested in other
people's experiences.
- David Wang
ATI
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From: [ A Modern Major General ]
John,
I need to remain anonymous please ... thanks!
I am closing out on a 2 M gate equivalent chip (mix of logic, memory and
cores) and I'm moving onto something nearly 4X the complexity.
I used Primetime for timing closure, both on a block and top level -- two
levels of hierarchy from a physical design perspective. One thing is clear
for the next chip -- there is no way I'll be able to run a full netlist in
PrimeTime, especially if I want to have results in a reasonable amount of
time.
To read in the full netlist, back annotate (DSPFs) and do an update_timing
took about 2 hours. Generating very detailed timing reports, including
full path, clock skew, histograms, etc, took nearly 18 hours -- on a 900
MHz P-III running Linux with sufficient memory. (The chip has a dozen+
different clock domains to deal with, plus scan, bist, jtag, etc.)
To get run time down in the highly iterative early stages of timing closure,
I created block level ILMs to use for top level timing. This brought the
top level runtime down to 5-6 hours.
Overall, the ILM procedure worked reasonably well, but of course, wasn't
without its problems. Synopsys helped work around the problems in the
2000.11 drop with a set of procs, and the 2001.08 drop due shortly is
supposed to fix these problems, so that the procs are no longer needed.
As I ramp toward the next project, I'm interested in the ESNUG community's
experience on 5-10 M gate ASICs, especially comments on ILM usage, if anyone
has succeeded in staying on 32-bit CPUs or if they've had to move to 64-bit
platform, or any other information that can be shared.
I was surprised to look on the Synopsys SolvNet pages and only find one
article related to ILMs. Does that mean it hasn't been hammered on by the
design community to any great extent?
I would also be interested in any user feedback on PrimeTime-SI.
- [ A Modern Major General ]
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