Daniel Schnell wrote:
> > -----Original Message-----
> > From: Gilles Chanteperdrix [mailto:[EMAIL PROTECTED]
> > Sent: 15. maí 2007 12:16
> > To: Daniel Schnell
> > Cc: [email protected]
> > Subject: Re: [Xenomai-help] memcpy performance on Xenomai
> >
> >
> > Improving clock_gettime overhead by reading directly the tsc is my very
> > next task. If you want to check if the effect you measure is the result of
> > clock_gettime overhead, you can measure the duration of memcpy with the
> > native api service rt_timer_tsc, and convert the tsc difference with
> > rt_timer_tsc2ns.
>
> This was not the culprit. Same results.
Does your processor have a tsc ? If yes, do you compile Xenomai with
--enable-x86-tsc ? What happens if you disable the interruptions ?
>
> Does Xenomai replace the memcpy() call with an own implementation ? (I don't
> think so.)
>
> What about trashing of cash lines through context switches ? But then if we
> run it on Linux alone we should also have trashed cache lines. There should
> not be any difference.
> Is maybe the presence of a Xenomai POSIX thread cause a lot of ctx switches,
> even if only a memcpy is executed inside the thread ? Shouldn't Xenomai
> threads run totally uninterrupted if they have the highest prio ?
>
> Please could somebody actually run this test on his hardware and see if these
> differences between Xenomai POSIX skin and Linux native are happening there
> as well ?
If you want us to test the code, please send it, I mean the one adapted
to the native skin.
--
Gilles Chanteperdrix
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