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Re: [Xen-devel] RTDS with extra time issue


On 12.02.18 12:20, Andrii Anisov wrote:
Actually as per Meng's explanation and calculations the problem was on my side - wrong DomR task/VCPU parameters. I was running the system with dummy loads and values received from CARTS and all seems to be ok (no deadline misses occured).
Well, what I expressed as dummy loads was all domains are generic armv8 kernels with minimal fs'es running `dd if=/dev/zero of=/dev/null`, except DomR. In this case no DL misses occurred with parameters given by CARTS.

Now I have real driver domain, Android with GPU sharing. Loads are like youtube playback in DomA, dd from mmc through ssh in DomD. And I see unexpected DL misses for the same RT configurations.

Well this provides some ground for another my concern about XEN scheduling approach. My doubt is that scheduling is done within softirq, so all time spent with pcpu for exception itself and possible timer actions is accounted for the vcpu which context was interrupted. This seems to be not really fair and might be disruptive for RT scheduling.


*Andrii Anisov*

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