Re: [ANNOUNCE][RFC] PlugSched-6.2 for 2.6.16-rc1 and2.6.16-rc1-mm1

[Lee Revell]

On Mon, 2006-01-23 at 21:52 +0100, Paolo Ornati wrote:
> On Mon, 23 Jan 2006 15:25:37 -0500
> Lee Revell <rlrevell@xxxxxxxxxxx> wrote:
> 
> > This seems right to me, how do you expect X to be treated by the
> > scheduler?
> 
> Why moving the mouse a little (that causes a microscopic % of CPU
> being used) makes X priority jump up to 29 from 6/7 ???

> And why this doesn't happen when glxgears (for example) is running?
> (under cpu load this is different, with X never getting "good"
> priority -- if I remember correctly)
> 
> Maybe this is normal and depends on the way X sleeps or something...
> 

Because the scheduler favors interactive tasks (aka those which spend a
large % of time waiting on external events) and X is only considered
interactive when the mouse is being moved.  When glxgears is running
it's CPU bound and is therefore penalized.

> I don't know much about schedulers but if I'm able to make the cursor
> going in jerks with just a bit of CPU load (linux$ make -j16, for
> example) I wonder why X cannot get a better priority...
> 

Personally I don't see how we can expect to deliver OSX-caliber
multimedia performance using only generalized heuristics in the
scheduler (other OSes use hooks into the scheduler for multimedia).  At
the very least it seems you need isochronous scheduling and a
multi-threaded X server.

Lee

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/