On 11/19/2010 02:38 PM, Jim wrote:

I hate to have to tell you guys this , but !!!

My EEEpc playing justintv video is much better, the hesitation is so slight.
Playing the "Transformers", I just can't get over it.


Sorry, but that's just your perception.

This fix only affects TTYs (i.e. terminal sessions). For instance, if you're watching a video and compiling something in a terminal, this fix will make sure that the terminal as a whole (no matter how many background processes it starts) shares time fairly with your video player.
In other words, if you don't have a single terminal open, you shouldn't see any change at all.


In more detail, the specific problem is this:
* Kernel sees 10 CPU-hungry tasks: 1,2,3,4,5,6,7,8,9,10. Since the kernel doesn't know any better, it considers them equals and gives them same CPU time share (10%)

* In reality, process (1) is code compiling, (2)..(9) are started by (1) automagically, and (10) is a youtube video you're watching (because http://xkcd.com/303/).
(10) requires at least 50% CPU time or it'll be jittery.

* The solution, then, is to treat the *group* (1)..(9) as an equal to (10), and divide the time accordingly:
 (10) gets 50%, while (1)..(9) get 50/9 ~= 5.6%


HTH