Re: tvtime and the Linux 2.6 scheduler

[Nick Piggin]

Ingo Molnar wrote:
> * Con Kolivas <kernel@xxxxxxxxxxx> wrote:
>
>
> > >     33 ms : time per NTSC frame
> >
> > snip
> >
> > The followup email from someone describing good performance may help
> > us understand what's going on. Your example of poor performance is one
> > when the cpu performance is marginal to get exactly 30 fps processed
> > and on the screen. The cpu overhead in 2.6 is slightly higher than 2.4
> > so a borderline case may be just pushed over. 
>
>
> most of the cpu overhead comes from HZ=1000. Especial with SCHED_FIFO
> there should be minimal (if any) impact from the scheduler changes -
> SCHED_FIFO tasks get all CPU time, no ifs and whens.
>
> could people who experience tvtime performance problems apply the patch
> below to change HZ back to 100? Does it have any impact?

Just one other thing - realtime scheduling was basically broken up
until around 2.6.5. Before starting any tests, please ensure first
that you are using at least the 2.6.5 kernel. Thanks.
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