Re: The uncatchable jitter, or may the scheduler wars be over?

[Ove Karlsen]

On Sun, 04 Nov 2012 18:03:58 +0100, Lukasz Sokol <el.es.cr@xxxxxxxxx>  
wrote:

> A word of addition,
>
> On Sun, Nov 4, 2012 at 2:04 PM, Uwaysi Bin Kareem
> <uwaysi.bin.kareem@xxxxxxxxxxxxxxxxxxxx> wrote:
> [snip]
> > Also like I stated elsewhere, since daemons seem to make a difference,
> > optimally putting daemons or processes that can, on a low-jitter queue,
> > transparent to the user, seems optimal. Unfortunately realtime is not  
> > quite
> > working as one would expect, causing input to be choked at times, if you
> > want to have one main app, and the rest on sched_other, as a low-jitter
> > queue. So I am still iterating this.
>
> Hard real time kernel, will make the situation even worse: there the  
> userspace
> will get preempted always and no matter what it is doing; RT means here,
> the userspace will /get/ the slice, but whether the slice will be  
> enough, no one
> can guarantee but whoever wrote the userspace.
> It's the userspace that must decide 'do I have enough time to run
> another rendering loop within
> this time slice (or before vsync is imminent)'.
>
> (As in: real time is not 'as fast as possible' but 'as fast as
> specified' and the specification
> need to be within reason).
>
> >
> [snip]
> > Peace Be With You.
>
> Lukasz

I meant realtime-thread here, not added preemption points, for  
realtime-behaviour.
But I understand your point. So "low-jitter" is ofcourse the sweetspot,  
where you have just enough interrupts and preemption points, for exactly  
that, but not too much.

Peace Be With You.

--
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/