Re: [Xenomai-help] pthread cancelation and scheduling magics

[Philippe Gerum <rpm@xenomai.org>]

Wolfgang Grandegger wrote:
> Gilles Chanteperdrix wrote:
>> Wolfgang Grandegger wrote:
>>> Gilles Chanteperdrix wrote:
>>>> For architectures with a high-resolution counter,
>>>> clock_gettime(CLOCK_MONOTONIC) is a xenomai service which uses the
>>>> counter and does not issue any syscall, this includes arm unless you
>>>> configured xenomai with --enable-arm-arch=generic or with
>>>> --disable-arm-tsc, and this probably includes powerpc.
>>>>
>>> clock_gettime() is wrapped to __wrap_clock_gettime(), which does a syscall:
>>>
>>> http://www.rts.uni-hannover.de/xenomai/lxr/source/src/skins/posix/clock.c?v=SVN-trunk#058
>>>
>>> Have I missed something?
>> Yes, read the code again.
> 
> I was aware of CONFIG_XENO_HW_DIRECT_TSC but didn't look it up correctly
> :-(. It is set for my ARM  but not for my PowerPC system. Which explains
> some differences.
>

We do have direct TSC readings on powerpc as well by looking at the timebase
register from userland, but this only applies to rt_native_tsc(), or
clock_gettime() when using CLOCK_MONOTONIC in aperiodic mode.

> Wolfgang.
> 
> 
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-- 
Philippe.