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Slow ncls in AMS

twen


Hi, I am in the process to convert a Spectre/APS testbench into an AMS/APS testbench. I can simulate my old pure analog testbench with AMS/APS with the expected results. After I added a very simple verilog/AMS view and connected it to the DUT in my testbench and press the run button in ADE, I noticed there is a ncls process running for about 10 minutes before elaboration. What does it do and why is it so much slow?

ncls -64bit -verilog -f /mytb/ams/config/netlist/findPackageOpt

// IC subversion:  IC6.1.6-64b.500.14
// IUS version: 15.20-s004

Thanks,
TJ

  • Hi TJ,

    This is a bug in INCISIVE15.1 s016 and INCISIVE15.2. It will be fixed in INCISIVE 15.1-s020 and INCISIVE 15.2-s005 - both due by end of May (the 15.2 fix is due in the next couple of days, and the 15.1 fix in about a week).

    The workaround is to switch back to an older version. An engineering hotfix can also be made available if this is urgent and switching to an older version is not an option.

    I was about to write up a support article for this (I've hit it twice in the last week) but a colleague has beaten me to it - here's the article.

    Regards,

    Andrew.

  • When I manually ran ncls with exactly the same arguments when Virtuoso invoked it, it finished in a jiffy:

    % cat /tb/ams/config/netlist/findPackageOpt
    -nowarn DLWNEW -depend mylib.mycell:systemVerilog

    % time ncls -verilog -f /tb/ams/config/netlist/findPackageOpt
    ncls(64): 15.20-s004: (c) Copyright 1995-2016 Cadence Design Systems, Inc.
            module mylib.mycell:systemVerilog (VST)
    0.003u 0.017s 0:00.10 10.0%     0+0k 0+16io 0pf+0w

    I also created a small testbench with only the newly created systemVerilog view instantiated and it also took about 10 minutes to do the ncls. I am running on a RHEL 6.4 with plenty of free memory and cpus.

  • Hi, Andrew,

    I switched back to INCISIVE 14.20.014 and ncls won't stall any more.

    Thank you very much,

    TJ

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