Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]

Florian Schmidt
2004-10-31T13:28:23Z

On Sun, 31 Oct 2004 14:22:37 +0100
Ingo Molnar <mingo@elte.hu> wrote:

> cool! May i have a feature request :-) It would be quite useful to have
> an option to see the jitter output in percentage and in microseconds as
> well. I.e. an option to have such a format:
>
> late wakeup: +151.3 usecs (14.6%) jitter.

yep, will do so ater trying the 0.6.1 kernel.

> cycles are too large to be human readable, and absolute values are
> harder to read when HZ is not 1024. So to get a 'quick feel' of the
> delays in a system the above line would be the most informative (for me
> that is). Also, the percentage can go back to %.1f i think, instead of
> %.5f or so - it's good to have a decimal point in the percentage but one
> number after it is more than enough.) The more compact the output, the
> fewer useless info, the quicker the human brain can read it. (Obviously
> to generate a nice graph out of it needs a different format.)

well, to generate graphs out of the data one can choose to write the raw
cycle counts into a "history file". Then one can process this raw data to
hearts content. i will update the output routines to truncate the percentage
to %.1f [or the c++ equivalent :)]

>
> > Here's a typical run (still on V0.5.16, will try V0.6 now):
>
> please try -V0.6.1, -V0.6 had a pretty stupid bug that could trigger
> frequently.
>
> > threshold violations: 20
> > max jitter: 58.1228%
>
> here it would also be useful to have the 'max jitter' in usecs. I.e. in
> the above case it was somewhere around ~570 usecs.

ack.

flo