[LITMUS^RT] running a task as its execution time

[Youcef Amine Benabbas]

Hi Giovani,

On Thu, 2012-06-14 at 12:21 -0300, Giovani Gracioli wrote:
> Hello everyone,
> 
> 
> just recompiled the kernel with the modifications and the bug is
> fixed. Thank you Björn.
> 
> 
> I have two more questions. The current version of LITMUS is equivalent
> of which version in the paper "On the implementation of Global
> Real-Time schedulers"? I suppose it is, FE1, with fine-grained ready
> queue, event-driven scheduling, and 1 cpu handling interrupts, Am I
> right?
> 
> 
> I would like to measure also the overhead to send an IPI. Are the
> feather-trace SEND_RESCHED_START and SEND_RESCHED_END events used to
> measure IPI overhead?

Yes, they are equivalent. I am working on measuring this overhead plus
other overheads to implement overhead-aware schedulability tests.

By the way, I am trying to get a TS_SEND_RESCHED_(START/END) for
real-time tasks, i.e. timstamps with task_type==TSK_RT. Unfortunately I
could not get such timestamps. 

I followed execution paths producing TS_SEND_RESCHED, but it seemed to
me impossible to get them. 

I would appreciate your advice regarding measuring IPI latency for
real-time tasks.

Best regards,
Youcef  


> 
> 
> Best regards,
> Giovani
> 
> On Thu, May 31, 2012 at 4:46 AM, Björn Brandenburg <bbb at mpi-sws.org>
> wrote:
>         On May 31, 2012, at 7:34 AM, Jonathan Herman wrote:
>         
>         > We encountered this same issue with the mixed-criticality
>         > and EDF-HSB schedulers. Our poor implementation was to
>         remove the '&&
>         > !preempt' before job_completion in the _schedule method, and
>         > compensate by adding a check for is_queued(task) in the
>         _requeue
>         > method so that job_completion could be called after a
>         preemption
>         > without causing a BUG.
>         >
>         >> It seems to me the right thing to do is to not add unlinked
>         tasks to the ready queue if they have no budget remaining.
>         Then it is safe to process the job completion even if it
>         coincides with a preemption.
>         >
>         > This is a better solution.
>         
>         
>         
>         I have pushed a proposed fix to prop/budget-bug-fix. It seems
>         to fix the issue for me. Everyone, please test & review.
>         
>         Giovani, can you please confirm that this fixes the bug?
>         
>         Thanks,
>         Björn
>         
> 
> 
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