I don't know what you did with your PC...
On my P4 3.00E/Xp Pro Sp3 Dosbox is using 1-3% of CPU for "cycles"=8000.

core dynamic/normal?
or output

Maybe he accidentally hit the core changing hotkeys in a certain build

Here are the settings used on both PCs

core=auto
cputype=auto
cycles=8000
cycleup=10
cycledown=20

fullscreen=false
fulldouble=false
fullresolution=original
windowresolution=1280x960
output=ddraw
autolock=true
sensitivity=100
waitonerror=true
priority=higher,normal
mapperfile=mapper-0.74.map
usescancodes=true

The P4 in question is a Northwood A (2.4/400MHz FSB, 512L2)
The C2D is a T5600 (1.83/667MHz FSB, 2MB L2)

I'm definitely not hitting any hotkeys. There are no other programs running on the P4; as soon as I exit DOSBox, the CPU idles at 0%.

Perhaps there is graphics hardware acceleration on the one computer, but not on the other? (Does that make sense?)

DOSBox uses 3D acceleration in ddraw mode?
The P4 has a PCI Radeon 9250 in it, and the C2D uses integrated GMA950, so neither of them have very much graphics horsepower.

try with
windowresolution=original
output=surface

Surface output @ original resolution does not make a difference. It's still peaking at 72% (and average usage is around 55-60%).

Just tried DOSBox on my Opteron 185 (a dual core @ 3GHz) and CPU usage was only 0-2%. The Opteron and C2D (and Gamecollector's P4 3.00E) have SSE3, but my P4-A only has SSE2. Maybe the instruction set is making the difference?

Which version of DOSBox? (and where did you download it?)
Are the graphics card drivers updated?
Which OS?

DosFreak wrote:

Which version of DOSBox? (and where did you download it?)
Are the graphics card drivers updated?
Which OS?

0.74, downloaded from sourceforge. Graphics drivers are reasonably up to date on all three machines. (like most Vogons members, I have my favourite driver versions. 😜)

The P4 runs XP. The C2D and Opteron both run Win7.

The P4 does run DOSBox smoothly, despite the much higher CPU utilization. Just wondering why the P4 needs ~64% CPU to do what the Opteron and C2D can do with ~2%.

That P4 probably has an AC'97 "codec" audio card...in reality, that's the CPU working, also, on a multicore system when only one core gets extremely loaded the total CPU usage won't reach 100% (look at the attached pic. I'm using ~100% of one core).

bloodbat are all 6 cores uses when you play .mp4 movies? do all go to max when you use fast forward? If you switch to 12 threads are they all also fully used? And what is your cpu?

Does CPU usage drop significantly when you set frameskip to 10?

CPU usage is 4-22% when frameskip=10.

Does the DOSBox status window report an error, like something with windib?

No errors in the status window.

robertmo wrote:

bloodbat are all 6 cores uses when you play .mp4 movies? do all go to max when you use fast forward? If you switch to 12 threads are they all also fully used? And what is your cpu?

I don't know what that has to do with this thread, as I was only demonstrating what I explained by using a program I wrote to set the core to max usage; but...to answer your question...no. I'm watching a 1920 x 800 mp4 while I type this and total CPU usage is at ~7-10%, divided among all six cores. They didn't go to max when seeking (not even halfway). The CPU is a Phenom II X6 1090T. The program used to play the mp4 is Media Player Classic Home Cinema x64, whatever the latest version on their website is. Now...why do you ask?