[tz_vmm demo]- execution time

Martin Stein martin.stein at ...1...
Tue Sep 20 11:32:36 CEST 2016

Hi John,

Am 20.09.2016 um 01:46 schrieb John David:
> Dear Martin,
> Thanks a lot for your answers.
> I wanted to use the performance counter for more performance
> measurements such as cache-misses, but I don't know how to access and

I forgot to mention that you could also transform the performance
counter values into time values. On ARMv7 the counter counts every
single CPU cycle. Thus, you can use SECONDS = PERF_COUNTER / CPU_FREQUENCY.

> use it in the secure world userland. Could you please give me some

If you have the performance counter enabled in the SPECS, you can
include 'trace/timestamp.h' and read a timestamp via
'Genode::Trace::Timestamp Genode::Trace::timestamp();'.

> hints? is there any reading material on this?

I think [1] illustrates the use of the timestamp/performance counter
pretty good. The only document I could find to read about perfomance
counter access in general is the ARMv7 Manual [2] paragraph "C12.7
Counter access". If you have further questions, don't hesitate to ask.


[1] base-nova/src/test/platform/main.cc

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