High CPU load when playing video in WIndows XP guest

[ezjd]

Starting from VBox 3.X, I found video playback eats a lot of CPU in Windows XP guest under Linux Host (I tried Ubuntu 9.04, 9.10, 10.04).

For normal screen resolution (1024X768), full screen video playback takes ~80% of both cores of my AMD Atholon X2 64, and if in higher resolution, it will take 100% of both cores and can't get smooth video.

I tried different combination of options like 1 or 2 virtual CPU, HW/SW virtualization, with or w/o guest addon, and with or w/o 3D, 2D acceleration, but no change is noticeable. I even tried OSE version provided by Ubuntu and binary version from virtualbox.org, but no difference.

However, guest CPU load wasn't high at ~30% so that I highly suspect it is video buffer copying issue or video driver issue.

In VBox 2.x, it was OK though only one core (or max 50% of both core) will be used while normally it was under 80% for a core and didn't see choppy video playback with high screen resolution. Unforrunately, I can't use 2.2.4 under Ubuntu 10.04 because of KLM build failure.

[ezjd]

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