[LITMUS^RT] The gap between the release time and the real beginning of execution

[Björn Brandenburg]

> On 19 Jul 2016, at 12:05, shijunjie92 <shijunjie92 at gmail.com> wrote:
> 
> Hello:
>  
> The previous pic 'temp.jpg' is snipped from the tutor16's slides http://www.litmus-rt.org/tutor16/slides.pdf <http://www.litmus-rt.org/tutor16/slides.pdf>
> The 'temp_2.jpg' and 'temp_3.jpg' are snipped from my platform. You can see the gaps in different period are variant and unpredictable.
> I run the xubuntu img on virtualbox, and the hardware information is listed as follows:

Ok, then this is expected. Virtualization is not transparent with regard to timing. The virtualized OS cannot possibly offer better timing than the underlying hypervisor (+ overheads!).

The effect that you are seeing should go away (e.g., the gaps should be really, really small) if you run on real hardware.

- Björn


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