Re: [ECOS] simple eCos profiler

[Andrew Lunn <andrew.lunn@ascom.ch>]

> Yep, you're right:
> 
> My profiler is based on the system tick interrupt.  I AM aware of
> the inherit problems of doing it this way but this was the most
> portable way of doing it.  For a heavily loaded system, doing it
> this way shouldn't skew results too much I don't think.

When i wrote my profiler i did not like the idea of using the system
tick interrupt, even thought its more portable. Timer actions will be
triggered by the timer tick, which have an important affect on the
flow of execution in an RTOS. Thus your profiler will give squewed
results which tend to show more of the low priority background tasks
which are always running and less of the higher priority tasks which
are general somehow linked to the system clock. 

I used a second timer which i set to run at a different frequency
which is not a multiple of the system clock. This should give more
accurate results. The down side is its less portable since it has to
play around with the hardware to setup this timer.

What would be nice is to split the code into two halfs. One to setup
the interrupts etc, which would be hardware dependent and the second
half to actually do the logging. We could provide a generic version
using the system tick and the option to add hardware specific
implementations using other timers.

     Andrew

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