'TIME' task cpuuse

[Joel Sherrill]

On Tue, Jan 14, 2020 at 7:37 AM Matthew J Fletcher <amimjf at gmail.com> wrote:

> Of course without nanoseconds support in the BSP measuring the timer
> callback duration is difficult as most calls will be less than a tick.
>

Yeah, you can't use the clock services from rtems in that case since they
don't have a high enough resolution.

Do you have a free running counter/timer you can read?

I assume you only have a finite number of timer service routines called
from
the Timer Server thread. Can you benchmark them outside the application?
If this is a straightforward case of a single invocation of a method
running too
long, that would be sufficient to figure it out. Or do you have something
that is
processing a set of things and sometimes the set is large?

Hmmm... it is possible that if the clock tick configured is larger than any
of
your timer intervals, they are firing in clusters. Say you have a 10
millisecond
clock tick configured and all your timers fire in less than that. They will
all
fire in 1 tick. Any chance of a degenerate set like this?

--joel


> On Tue, 14 Jan 2020 at 08:41, Matthew J Fletcher <amimjf at gmail.com> wrote:
>
>> Ok,
>>
>> So first step is to create a wrapper that all timers fire through, then
>> an array to count the number of invocations per timer_id, after that some
>> per timer_id time accounting.
>>
>> Will let you know if its anything outside my application.
>>
>>
>> On Mon, 13 Jan 2020 at 15:01, Joel Sherrill <joel at rtems.org> wrote:
>>
>>>
>>>
>>> On Mon, Jan 13, 2020 at 8:53 AM Matthew J Fletcher <amimjf at gmail.com>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> My application seems to be using around 1/3rd of its total cpu usage in
>>>> the 'TIME' task,. is this the task created by rtems_timer_initiate_server()
>>>> ?
>>>>
>>>
>>> Yes.
>>>
>>>>
>>>> What would be the best way to get more information,. are there console
>>>> commands that would emit more data, or do i need to instrument my
>>>> application to see usage of all rtems_timer_xx callbacks ?
>>>>
>>>
>>> rtems_timer_server_xx would be the ones going to the TIME Server.
>>>
>>> But 1/3 seems quite excessive. I would assume one of your timer server
>>> routines is doing something unexpectedly heavy CPU-wise.
>>>
>>> I don't think there is any instrumentation in the server which would
>>> help. Measuring the execution time of each invocation is what comes to
>>> mind. My first thought is that this would be a nice debug option for
>>> timers. But I am not sure how good this would be for ISR style.
>>>
>>> --joel
>>>
>>>>
>>>> regards
>>>> ---
>>>> Matthew J Fletcher
>>>>
>>>> _______________________________________________
>>>> users mailing list
>>>> users at rtems.org
>>>> http://lists.rtems.org/mailman/listinfo/users
>>>
>>>
>>
>> --
>>
>> regards
>> ---
>> Matthew J Fletcher
>>
>>
>
> --
>
> regards
> ---
> Matthew J Fletcher
>
>
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