[LITMUS^RT] high miss ratio for low task utilization

[Björn Brandenburg]

Hi JP,

thanks for reporting the issue. I'm not sure what's going on. Can you recreate the issue without the scripts (which are a black box to me) just by running & tracing a couple of rtspin instances?

> On 20 Nov 2014, at 22:01, jp walters <mailinglistjp39 at gmail.com> wrote:
> 
> root at ubuntu-qemu:~/experiment-scripts# ./parse_exps.py run-data/test1
> Loading experiments...
> Parsing data...
>  0.00%
> Writing csvs into parse-data...
> Too little data to make csv files, printing results.

What does the above line mean?

> <ExpPoint-run-data/test1>
>            block-avg:  Avg:     0.000  Max:     0.000  Min:     0.000  Var:     0.000
>            block-max:  Avg:     0.000  Max:     0.000  Min:     0.000  Var:     0.000
>           miss-ratio:  Avg:     1.000  Max:     1.000  Min:     1.000  Var:     0.000
>          record-loss:  Avg:     0.000  Max:     0.000  Min:     0.000  Var:     0.000
>             tard-avg:  Avg:     0.000  Max:     0.000  Min:     0.000  Var:     0.000
>             tard-max:  Avg:     0.000  Max:     0.000  Min:     0.000  Var:     0.000
> 
> The 1.0 miss-ratio seems odd to me, given the resources available and the workload described in the 3 tasks example.  Am I missing something?

This indeed seems odd. Miss _all_ deadlines? Even under moderate overload you would expect *some* jobs to complete before their deadlines. At the very least, the first jobs to be scheduled should not miss their deadlines.

This means either that LITMUS^RT is somehow horribly broken or that the experimental setup isn't quite doing what it's supposed to. Let's try to narrow this down by using a simpler setup.

Thanks,
Björn