( ESNUG 416 Item 8 ) -------------------------------------------- [07/30/03]
From: [ A Little Bird ]
Subject: User Concerned About DC/PhysOpt 2003.06-1 Poor Quality Of Results
Hi, John,
Please keep me anon.
We are facing some QoR issues on the new Synopsys version. We're comparing
the 2002.05-SP2, 2003.03-1, 2003.06-1 versions of DC/PhysOpt using the exact
same compile scripts. We are trying both the rtl2pg and the gates2pg
synthesis methodologies.
Together with another team, we found QoR degradation on all 8 of the designs
we were testing in regression. I do not have on 6 of them, they're running
on other site, but on the 2 we were testing here, we found that we have a
5-10% path delay difference with 2002.05-SP2 to 2003.03-1 & 2003.06-1
versions using the exact same compile scripts!
We are trying both the rtl2pg and the gates2pg synthesis methodologies. We
tested the gates2PG flow, although we already know that currently Synopsys
admits that the compile_physical will give poorer results. We saw that the
results at the end of Design Compiler runs are very close between the 3
versions -- but the starting point of the PhysOpt, after the create
placement is showing a 10-15% degradation in WNS.
I will be glad to hear if other users do see this bizarre trend. We are
familiar with the fact that each version released by Synopsys must have a
testing to find all the hidden changes and affects, but this is way beyond
our expectations. We see the improved runtime - but it comes in place of
good timing results. Is anyone else seeing this, too?
- [ A Little Bird ]
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