[LITMUS^RT] Installing LITMUS RT on Odroid XU4

[Glenn Elliott]

>> I increased the buffer size of each cpu core in
/sys/kernel/debug/buffer_size_kb, but the problem still exists!

> I’m not sure how you hit on that setting, but I don’t think it has
anything to do with LITMUS^RT. The LITMUS^RT trace buffers are configured
statically via .config.

To clarify: "/sys/kernel/debug/tracing/buffer_size_kb" is an ftrace
configuration parameter (
https://www.kernel.org/doc/Documentation/trace/ftrace.txt).  Linux's ftrace
is distinct from Litmus's "feather trace."  The size of feather trace
buffers is controlled by the .config parameter
CONFIG_SCHED_TASK_TRACE_SHIFT (see litmus/Kconfig).

-Glenn

On Tue, May 21, 2019 at 8:45 AM Björn Brandenburg <bbb at mpi-sws.org> wrote:

>
>
> > On 20. May 2019, at 18:35, sobhan niknam <sobhan.niknam at yahoo.com>
> wrote:
> >
> >
> >
> >> On 20 May 2019, at 17:40, Björn Brandenburg <bbb at mpi-sws.org> wrote:
> >>
> >> On 20. May 2019, at 16:40, sobhan niknam <sobhan.niknam at yahoo.com>
> wrote:
> >>>
> >>> There is no log file in /dev/litmus to look at.
> >>
> >> I’m not talking about a LITMUS^RT-specific device file. Check the
> standard kernel log.
> >
> > The buffers overflowed:
> >
> > May 21 01:12:37 odroid kernel: [341828.508325] [c1] Failed trace writes:
> 25486
> > May 21 01:12:37 odroid kernel: [341828.508344] [c3] Failed trace writes:
> 46617
> > May 21 01:12:37 odroid kernel: [341828.508364] [c0] Failed trace writes:
> 19335
> > May 21 01:12:37 odroid kernel: [341828.508381] [c2] Failed trace writes:
> 0
> > May 21 01:12:37 odroid kernel: [341828.508619] [c2] Failed trace writes:
> 6915121
> > May 21 01:12:37 odroid kernel: [341828.508627] [c0] Failed trace writes:
> 6713421
> > May 21 01:12:37 odroid kernel: [341828.508696] [c3] Failed trace writes:
> 23201
> > May 21 01:12:37 odroid kernel: [341828.511328] [c3] Failed trace writes:
> 7169319
>
> Makes sense. If you have gaps in the record, then of course the resulting
> traces will be incomplete and/or strange.
>
> >
> >>> However, what should I do if supposing the trace buffers overflowed?
> >>
> >> If you have enough memory, increase the trace buffer size. Otherwise,
> make sure they get drained quickly enough.
> >
> >
> > I increased the buffer size of each cpu core in
> /sys/kernel/debug/buffer_size_kb, but the problem still exists!
>
> I’m not sure how you hit on that setting, but I don’t think it has
> anything to do with LITMUS^RT. The LITMUS^RT trace buffers are configured
> statically via .config.
>
> - Björn
>
>
> _______________________________________________
> litmus-dev mailing list
> litmus-dev at lists.litmus-rt.org
> https://lists.litmus-rt.org/listinfo/litmus-dev
>
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