100% CPU with ntvdm.exe

[H. M.]

Hi there.

Win2K, SP4

I have one DOS program when I use it, the CPU indicator goes to 100%.
Looking at the processes tab of Task Manager, it's always "ntvdm.exe" that
consumes the whole CPU power.
Moving around to other apps becomes so slow and sluggish.
Several seconds after that DOS program loses the focus, the CPU usage goes
back down to normal even though
the DOS program still running. Go back to the DOS program, the CPU goes up
again.

Other DOS programs I have don't have the same behavior.
Any idea.

Thanks.
Hosam.

 

[BillW50]

Hi there.

Win2K, SP4

I have one DOS program when I use it, the CPU indicator goes to 100%.
Looking at the processes tab of Task Manager, it's always "ntvdm.exe" that
consumes the whole CPU power.
Moving around to other apps becomes so slow and sluggish.
Several seconds after that DOS program loses the focus, the CPU usage goes
back down to normal even though
the DOS program still running. Go back to the DOS program, the CPU goes up
again.

Other DOS programs I have don't have the same behavior.
Any idea.

Thanks.
Hosam.

Got the PIF Properties under the Advance tab checked for the
background for this DOS application? That should help, although the
application won't run in the background anymore if that is
important.

Other than that, some DOS programs don't share the CPU fairly under
some OS like Windows 2000, XP, and OS/2. As the OS thinks such
things as reading the keyboard buffer while the DOS application is
doing nothing is something useful that the DOS application needs to
do. OS try to figure such CPU tasks are not important (as the OS
handles this task for the application anyway). But some DOS
applications are written in a way that the OS just doesn't get it.

So what does this DOS application do anyway?




Cheers!


______________________________________________
Bill (using a Toshiba 2595XDVD & Windows 98SE)
-- written and edited within WordStar 5.0

 

[Guest]

I have a fairly old DOS data logging application that I still use.
By setting the priority of NTVDM to LOW the problem goes away.
NTVDM will still appear to use all available CPU time, however any other
process that needs CPU time will prempt the DOS mode NTVDM emulator.
Probably not a M$S recommended solution, but it works for me.
I should add that all I am collecting is weather data, so if it's a little
slow it does not matter. This shold not be used with anything like a near
real time control system.

 

[H. M.]

Date: Mon, 26 Sep 2005 03:05:48 +0900

Hi there.

Win2K, SP4

I have one DOS program when I use it, the CPU indicator goes to 100%.
Looking at the processes tab of Task Manager, it's always "ntvdm.exe" that
consumes the whole CPU power.
Moving around to other apps becomes so slow and sluggish.
Several seconds after that DOS program loses the focus, the CPU usage goes
back down to normal even though
the DOS program still running. Go back to the DOS program, the CPU goes up
again.

Other DOS programs I have don't have the same behavior.
Any idea.

Thanks.
Hosam.

Got the PIF Properties under the Advance tab checked for the
background for this DOS application? That should help, although the
application won't run in the background anymore if that is
important.

Other than that, some DOS programs don't share the CPU fairly under
some OS like Windows 2000, XP, and OS/2. As the OS thinks such
things as reading the keyboard buffer while the DOS application is
doing nothing is something useful that the DOS application needs to
do. OS try to figure such CPU tasks are not important (as the OS
handles this task for the application anyway). But some DOS
applications are written in a way that the OS just doesn't get it.

So what does this DOS application do anyway?

Cheers!
--------------------------------------------------------------
The program is "STEP5" from Siemens for working with PLCs.
The program must continue working on the background too
I tried changing different settings of the PIF properties to match other DOS
program the has no
problem with ntvdm, but still same behavior.

By the way, under Win9x, the program response is very fast and working with
many apps while STEP5 is running
has no effect on the performance of any app.

Thanks.

 

[H. M.]

I tried the priority level idea.
The overall performance is much better.
As you wrote, the CPU still showing 100%, but changing to other apps is as
fast as normal.
I should add however, that I'm working OFFLINE now. I should re-test the
idea while
connected to the PLC (which the DOS app does as I wrote in other msg).

Thanks.