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CPU Usage shoots from 5% to 100% as soon as Virtual PC starts

Source: microsoft.public.virtualpc
Sent: 02/05/2006
From: Mike
Message:

Hi,

I am using a PIII 1.13GHz machine with 384 MB Ram. Win XP is installed on
the host. The machine runs fine. CPU Usage as shown by the host normally
varies from 2-20 programs, even if I run 4 or 5 programs simultaneously.
But, as soon as I start the Virtual PC, CPU usage goes to 100% and remains
100% as long as the Virtual PC is running. As soon as I shut off the virtual
PC the CPU usage drops to normal that is around 2-5%.

Why is it so? Why CPU usage is so high. Can it affect the CPU?

Awaiting a reply.

Regards Mike.

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Related Messages

Re: CPU Usage shoots from 5% to 100% as soon as Virtual PC starts

Sent: 02/05/2006
From: Steve Jain <(email address - cut out)>
Message:

On Sun, 5 Feb 2006 07:29:27 -0800, "Mike"
<(email address - cut out)> wrote:

What OS(es) are you running in VPC? If you're running older OSes like
DOS or Win9x, this is expected behavior without the VM Additions.
Those older OSes have no CPU Halt command when they're idle.

--
Cheers,
Steve Jain, Virtual Machine MVP
http://vpc.essjae.com/
"This posting is provided "AS IS" with
no warranties, and confers no rights.
You assume all risk for your use.
I am not am employee of Microsoft."

Show quoted text

>Hi,
>
>I am using a PIII 1.13GHz machine with 384 MB Ram. Win XP is installed on
>the host. The machine runs fine. CPU Usage as shown by the host normally
>varies from 2-20 programs, even if I run 4 or 5 programs simultaneously.
>But, as soon as I start the Virtual PC, CPU usage goes to 100% and remains
>100% as long as the Virtual PC is running. As soon as I shut off the virtual
>PC the CPU usage drops to normal that is around 2-5%.
>
>Why is it so? Why CPU usage is so high. Can it affect the CPU?
>

RE: CPU Usage shoots from 5% to 100% as soon as Virtual PC starts

Sent: 02/09/2006
From: augustus_meyer
Message:

Hi Mike,

Steve told you in general, why this effect happens.
Old DOS-programmers did not consider the possibility of multi-programming,
beacuse DOS itself was single user OS.
So DOS-programs usually did nor elease the CPU to wait for some work, in
case of "idle" state. For instance, when waiting for keyboard input, programs
simply looped continously to check the keyboard-input buffer instead of
waiting for an interrupt from the keyboard interface.
So DOS-program is always active within VPC, which results in the CPU-load
you see.
However, 100% is too much. 50% it should be, but that depends upon priority
of VPC.
But may be, there is some help for you.
IF you have sources of the DOS-program, THEN it is possible to introduce
special code to let the DOS-program really "wait for something to happen"
using interrupts, thus releasing the CPU to the XP host.
I did it myself wth a BASIC program for DOS running under VPC. CPU load
dropped from 50% to about 5%.
Depending how important it is for you, it should even be possible to "hack"
the binary in case no sources available.

Show quoted text

> 100% as long as the Virtual PC is running. As soon as I shut off the virtual
> PC the CPU usage drops to normal that is around 2-5%.
>
> Why is it so? Why CPU usage is so high. Can it affect the CPU?

Re: CPU Usage shoots from 5% to 100% as soon as Virtual PC starts

Sent: 02/09/2006
From: Steve Jain <noreply.-at-.essjae.com@>
Message:

On Thu, 9 Feb 2006 01:58:27 -0800, "augustus_meyer"
<(email address - cut out)> wrote:

also, running the idle.com TSR included with the VM Additions for DOS
will send the CPU halt as necessary.

--
Cheers,
Steve Jain, Virtual Machine MVP
http://vpc.essjae.com/
"This posting is provided "AS IS" with
no warranties, and confers no rights.
You assume all risk for your use.
I am not am employee of Microsoft."

Show quoted text

>
>> 100% as long as the Virtual PC is running. As soon as I shut off the virtual
>> PC the CPU usage drops to normal that is around 2-5%.
>>
>> Why is it so? Why CPU usage is so high. Can it affect the CPU?
>Hi Mike,
>
>Steve told you in general, why this effect happens.
>Old DOS-programmers did not consider the possibility of multi-programming,
>beacuse DOS itself was single user OS.
>So DOS-programs usually did nor elease the CPU to wait for some work, in
>case of "idle" state. For instance, when waiting for keyboard input, programs
>simply looped continously to check the keyboard-input buffer instead of
>waiting for an interrupt from the keyboard interface.
>So DOS-program is always active within VPC, which results in the CPU-load
>you see.
>However, 100% is too much. 50% it should be, but that depends upon priority
>of VPC.
>But may be, there is some help for you.
>IF you have sources of the DOS-program, THEN it is possible to introduce
>special code to let the DOS-program really "wait for something to happen"
>using interrupts, thus releasing the CPU to the XP host.
>I did it myself wth a BASIC program for DOS running under VPC. CPU load
>dropped from 50% to about 5%.
>Depending how important it is for you, it should even be possible to "hack"
>the binary in case no sources available.
>
>

Re: CPU Usage shoots from 5% to 100% as soon as Virtual PC starts

Sent: 02/15/2006
From: "Iwan" <(email address - cut out)>
Message:

if it's not due to DOS in the client, then i still believe that it's due to
your host computer not having enough resource to run the VPC client.

how much RAM did you allocate to the client?

"Mike" <(email address - cut out)> ditulis dalam berita
pesan:(email address - cut out)...

Show quoted text

> Hi,
>
> I am using a PIII 1.13GHz machine with 384 MB Ram. Win XP is installed on
> the host. The machine runs fine. CPU Usage as shown by the host normally
> varies from 2-20 programs, even if I run 4 or 5 programs simultaneously.
> But, as soon as I start the Virtual PC, CPU usage goes to 100% and remains
> 100% as long as the Virtual PC is running. As soon as I shut off the
> virtual
> PC the CPU usage drops to normal that is around 2-5%.
>
> Why is it so? Why CPU usage is so high. Can it affect the CPU?
>
> Awaiting a reply.
>
> Regards Mike.

Post Reply | This is Spam! | Mark as Spam

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