Comment 4 for bug 1285772

I know. But the use case and requirements have not been made explicit in
LNG. E.g. how many interrupts and context switches will occur per 1ms TTI
and how much of cycle budget can be used.
There are also other potential approaches that don't involve the kernel
doing context switches, e.g. with user space threads, if PREEMPT_RT doesn't
cut it.
Den 4 mar 2014 06:45 skrev "Kim Phillips" <email address hidden>:

> Wireless basestation applications need PREEMPT_RT_FULL, irrespective of
> NO_HZ_FULL, in order to meet e.g., 1ms LTE physical layer subframe
> requirement specifications. They can use NO_HZ_FULL iff enough cores are
> available, which is not a valid assumption given the variety of
> available solutions. For more details, see e.g., this paper:
>
> https://amplab.cs.berkeley.edu/wp-content/uploads/2012/08/cloudIQ.pdf
>
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> https://bugs.launchpad.net/bugs/1285772
>
> Title:
> NO_HZ does not work for RT kernels
>
> Status in Linaro networking Group:
> Confirmed
>
> Bug description:
> https://validation.linaro.org/dashboard/image-charts/LNG-NO_HZ
>
> Although recent patches have fix NO_HZ for linux-lng and the
> preemption build, the RT build fails with NO_HZ.
>
> This may be ok, if you have many cores running no_hz then you would
> have less need for the cores running the kernel to have the best
> possible latency ?
>
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