[LITMUS^RT] Right size for scheduling trace buffer

[Youcef Amine Benabbas]

Hi Mr. Glenn, Hi Dr. Brandenburg, Hello everyone,

On Thu, 2013-04-18 at 11:55 -0400, Glenn Elliott wrote:
> 3) Run the trace tasks as SCHED_FIFO task (check out the "sched_tool"
> utility).  This will ensure that any idle time from Litmus is spend
> flushing the ring buffers. (Note: Running tracers as SCHED_FIFO used
> to crash Litmus, but I believe it has been fixed).

Indeed, LITMUS^RT crashes. I run my tracing task, then set its priority
to (SCHED_FIFO, 50). 

When there are no litmus real-time tasks, everything is fine, however,
as soon as launch a couple of rtspins, with a wait for synchronous
release flag, the kernel crashes as I run release_ts, here is part of
the call trace:

resched_task
push_rt_task
post_scheduler_rt
schedule
? sub_preempt_count
do_nanosleep
hrtimer_nanosleep
? update_rmtp
? hrtimer_start_range_ns
sys_nanosleep
system_call_fastpath

RIP [.....] sched_state_will_scheduler

I am using litmus 2012.1. Does any one know if the problem was fixed
before this version? 

Regards,
Youcef