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NTVDM peaks to 100% CPU utilization with DOS.

Posted on 2003-03-11
Medium Priority
Last Modified: 2013-12-28
I am in a real bind here. The environment I work in is mixed Novell 4.x and Windows NT 4 Server environment.

We are transitioning off of this 16 bit application that communicates with an old Btrieve database that resides on a Novell 4.x server.

We have shortcuts to batch file that launches a DOS app.  When the DOS box launches the processor (machines are Compaq Evo 500s 2.4Ghz) pegs out to 100% and the application just sits there. If you open up the task manager you can see the NTVDM.EXE is the process that's eating up all of the processors resources.
Question by:timrha

Expert Comment

ID: 8118835
Is the application actually doing anything, or has it crashed? How did you run the application before this, Win95?

Unless your application is actully malfunctioning, I wouldn't worry about it. Windows can't tell when your DOS program is actually doing something (or not), so it allows the ntvdm to have any spare time i.e. time that would otherwise be idle time. If you start another program e.g. Internet Explorer, then it should run OK, and less time is used by your DOS app.

Expert Comment

ID: 8126447
We found that this is not only a WinNT problem but also Win2000. There is a fix existing (NTVDM.EXE at Microsoft)The ntvdm update is mentioned in Microsoft KB article 320694. http://support.microsoft.com/default.aspx?scid=kb;en-us;320694.

Accepted Solution

stevemjp earned 300 total points
ID: 8127919
it's known as 'flunking'

The NTVDM is the Virtual Dos Machine which runs wowexec (Windows On Windows).

Unfortunately NT nor 2000 can run 16bit and 32bit apps at the same time very well. The processor in effect switches from 16 to 32 bit mode.

As Roly Dee suggests, open up something else and see if that runs OK.

I would suggest that you run 16bit apps on their own server. Thats the best way to optimise performance

Expert Comment

ID: 8158416
The same Procedure with an old Application from me. Detail shows that its not NTVDM, nor wowexec - its a part of the real Application.

Microsoft told me that error would disappear with SP3 for WIN2K - a Programmer told me to use the NTVDM from the .NET Server.

I´ve tried both without any Result.

Maybe with SP4, or throw away that old Application!

regards Mike

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