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Subject: Isn't the Library Manager actually the problem with DM?

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svenn
Posts: 7
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9/07/2007 2:19 PM
I've been using Composer for about 10 years now and in my honest opinion the way the Library manager is working is the problem. Or to be more precise, the way it is not working, at least for 5.1.41. As the design goes on, a particular cellName will get a lot of cellViews: schematic, config, symbol, layout, av_extracted and so on, and now we can also have the ADE states saved as cellViews. This fills up the cellView column pretty fast, and if you want to have a little backup of a view, specially the av_extracted and layout views are very often duplicated as layouters experiment to reduce parasitics. Configs also tend to get plentiful as schematics are replaced with av_extracted views. If you use something like DesignSync then earlier revisions get suffixes added with _1_2 etc. and needless to say no engineer can guess just from such a name what to use if he is instantiating somebody elses design. The Library Manager need at least one more column where the viewVariants are listed. That way it would be possible to list variants of a cellView in a more user friendly way. Adding the possibility to place a comment on each variant that shows up in a text field inside the Library Manager somewhere would make "visual scanning" of design data easier. With such a viewVariants list you could "grey" out the versions of the cellView that are on DM and a right click on a particular variant could offer the possibility to check it out or to ask for a diff vs. the current version. Talking about diff reminds me that there is no real good way to "diff" views unless they are text. At least not in vanilla Cadence. Normally you would not check out a new version of a colleagues design unless he has made a lot of serious changes. Often you use the block of somebody elses design as a "load" or a "source" for your own design, and you wouldn't like to have that "schematic has been changed since last extraction" error if he is sleeping in Japan while you sweat in Europe and tape/out is tomorrow. Juat to exagerate. Library Manager hasn't changed much in 10 years and that is the core problem. If Cadence has fixed that for IC66.x then fine, then nothing will happen on DM until industry has migrated in about 5 years (or 1 year after EOL message for 5.1.x series from Cadence) -- Svenn

Britta
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Posts: 6
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9/14/2007 2:52 PM
Hi Svenn, I don't think the library manager is the problem for DM, it just makes an underlying problem more visible. I have worked on projects, where I counted in total 126 different 'layout' view names. Some cells had up to 10 different layout view names like layout_new, layout_save, layout_good, layout_2 etc. This is working style, personal preference, being afraid of loosing things... Data management does require a complete new way of thinking. If I am following the DM paradigm, then I check-in my work at stages, where it means something to me e.g first part of a functionality is implemented. I put useful comments in the log message, that hopefully still mean something to me in 6 months from now and hopefully somebody else does understand them too. I can go back to any earlier version that I checked in. This is nothing else then having layout_new or layout_save, just that they are named differently now. How many of those versions you see, depends on the work model you use. If you use a shared work model where many people work in the same work area, then yes, that can be plenty. If you work in a private work model, where the configuration only belongs to you, then you are the owner of what you see. A good way to deal with exploding views is to come up with naming conventions. You can enforce them with access controls if you want.You can not prevent them from being created, but you can prevent the users from checking them into your data base. I personally would not like to see something to be greyed out. You limit users what they can use or do and if somebody really wants to use schematic_1_2, why not? BTW, Only the DM tool could determine if something is managed or not. The library manager is coming from Cadence. Yes, it can be customized or completely re-written. That would have to be done from the DM vendor though. Cheers, Britta

svenn
Posts: 7
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9/25/2007 1:33 PM
Hi Britta, I have been doing some computer programming and have learned to like a good revision management for source code. Take project hosting sites like Sourceforge, for example, it would have been impossible for contributors and maintainers to keep the overview over even the smallest project without. CVS and SVN make it very easy for a programmer to check out the work of others or, before updating a local version, check what is the changes between the local and the remote version of a source code file. I think most CAD support people know this and try to be evangelists in their own companies. In the fight vs. hardheaded designers CAD support can only win if they deny a check-in programmatically. Designers are used to Cadence (the software) behaving in a special way and to core dump if you are trying to be too clever on something. If I understand your last paragraph right, the library manager should actually be written by the company that provides the DM. I agree with that as the design management in a vanilla Cadence setup is depending on the entire designer team having the same understanding of naming conventions, referencing rules etc. Vanilla Cadence does not offer an easy way to check the library referencing in designer views. When not using DM, you need to have intermediate libraries for work that is good enough for integration in a chip to avoid that the top-level designer has to check and save the hierarchy too many times a day due to designers working on their cells. Too often I see that local playground cellviews are referenced in intermediate releases. That happens to me, too, every now and then. Specially when something has to go very quick, and that is most often the case close to tape-out. When using design sync, it is very handy to use the DS tools to view the structure of the DM. As a designer I would like to have a possibility to just use that tool instead of the Library Manager just like I use the Hierarchy Editor when I start using extracted views. Since extracted views are normally not put into DM (at least my experience) you will have to take care of the setup for the extraction that you needed for that particular config. This is getting into the area of configuration management which adds another layer of abstraction on top of the data. Digital designers and software programmers are mostly fine with these tools as they handle text based design representation very well. Analog designers using Virutoso Schematic Capture have been waiting for a schematic diff for years as well as a feasible configuration management dashboard. The ADE could have been that, the VSdE could have been that, but frankly, the versions that are used currently by the industry, IC5.1.41 and VSDE41, throws windows at the user like no other software I have ever used. Then take into the fact that the internals of those windows does not scale if you maximize them, and you wonder what the guys at Cadence do all day. This may have improved with 6.x but none of the vendors PDK that we use have a roadmap for 6.x for the next 2 years which is good as keeping two radically different tool branches for different technologies is even more stressy on the designers (and the CAD support who has to know where the buttons are placed in to different versions)

smcbutler
Posts: 1
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5/11/2008 10:16 PM
sorry for the late posting but there is a schematic (and layout for that matter) diff tool that comes with the VersIC Cadence DM tool from MethodICs. - www.methodics-eda.com

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Forums > Special Topics > Design Data Management > Isn't the Library Manager actually the problem with DM?

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