why did Ubuntu turn off kernel preemption in Edgy?

Matthew Garrett mjg59 at srcf.ucam.org
Wed Nov 29 20:22:26 GMT 2006

On Wed, Nov 29, 2006 at 08:15:19PM +0100, Tobias Wolf wrote:
> Am Mittwoch, den 29.11.2006, 17:43 +0000 schrieb Matthew Garrett:
> > If the human eye is unable to distinguish movement at faster than the 
> > equivalent of 24 frames per second, then you'd see exactly the same 
> > thing in real life. You don't, which indicates that faster movement is 
> > still perceivable. In computer games, the difference between 30 frames 
> > per second and 60 frames per second is quite easy to distinguish.
> You do. There is pretty much the same aliasing (wagon wheels) in the
> visual system. The cinematic industry didn’t choose their FPS
> arbitrarily, they just underestimated it somewhat.

Sorry, I should have been clearer. I was only arguing against the 
idea that the human brain doesn't process visual information faster than 
24 frames per second. As you point out, similar effects can be generated 
in real motion, though I was under the impression that it still wasn't 
clear what was responsible for that - last time I had anything to do 
with this stuff, Reichardt detectors were a good model for certain 
aspects of human vision but hadn't actually been demonstrated to exist 
in the mammalian visual pathway?

> Flicker fusion frequency in high contrast regimes like screens is around
> that but in general depends heavily on the circumstances (luminance,
> contrast in-/decrement and others).
> I guess increasing FPS in games amounts to something different than
> perceptual flicker reduction.

Absolutely. The point at which flickering vanishes and the point at 
which an observer stops noticing an increase in fluidity of motion 
are presumably different phenomena, which is a good indication that 
different parts of the sensory systems process information at different 
rates. But this then gets way beyond my field of expertise, which is 
rather more related to fruitflies...

Matthew Garrett | mjg59 at srcf.ucam.org

More information about the ubuntu-devel mailing list