[LITMUS^RT] Running LITMUS-RT on ARM64

[Andrii Anisov]

On 28.08.17 16:57, Björn Brandenburg wrote:
> Well, rtspin’s spin loop is not "cycle accurate", so some variation is always possible. However, rtspin usually doesn’t show such large runtime variations (unless you specifically ask for it with -u/-U), so something else appears to be going on here.
Yep, I must do this experiment as well. But it would also take some time 
to get baremetal setup for my platform.

> Perhaps it is related to virtualized time? Can you reproduce the effect on bare metal (i.e., on native LITMUS^RT without any virtualization layer)?
I think it is not about virtualized time.
I guess I could explain task execution time stretching with the VCPU 
nature in a virtualized system. I.e. VCPUs are also scheduled, and it 
might be vcpu with a task running to be scheduled out from physical CPU, 
then scheduled in. So task execution time increases. But I can not 
explain to myself an execution time reduction.
Anyway I should also learn about rtspin internals and sort out what was 
said to me here[1].

[1] 
https://lists.xenproject.org/archives/html/xen-devel/2017-08/msg02351.html

-- 

*Andrii Anisov*