Re: [Xen-devel] RT-Xen on ARM

[Meng Xu <xumengpanda@xxxxxxxxx>]

[sorry, my finger slips. let me rephrase my last sentence.]

>
>> For example, if you have a particular task in the VM that you need must
>> absolutely execute for at least 10ms every 100ms, you can:
>> - inside the VM, pin the task to vCPU 0, and give it top priority;
>> - at the Xen level, give (with RTDS) to vCPU 0 budget=10ms and
>>   period=100ms (or maybe budget of 12ms, to allow for some overhead
>>   :-P).
>
> This assumes that the start time of the task's each period is
> synchronized with the start time of the VCPU's each period.
> If this assumption does not hold, the VCPU need a larger budget to
> guarantee the task will always have 10ms in *any* 100ms time interval.
> The budget can be computed by CARTS
> (https://rtg.cis.upenn.edu/carts/).
>
>>
>> This is something that no other scheduler allows you to do. :-)
>
> Exactly.
> If you want to reason about the real-time timing properties required
> by some safety-critical systems' standard, such as the ISO-26262 for
> automotive systems, the above computation and analysis will be
> required.

I mean:
If you want to argue about the real-time timing properties required
by some safety-critical systems' standard, such as the ISO-26262 for
automotive systems, the system support (such as the RTDS scheduler),
the correct configuration of the system, and the analysis  computation
and analysis will be required.

Thanks,

Meng
-----------
Meng Xu
PhD Candidate in Computer and Information Science
University of Pennsylvania
http://www.cis.upenn.edu/~mengxu/

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