On Sat, 2019-09-14 at 10:52 +0200, Juergen Gross wrote: > Switch rt scheduler completely from vcpu to sched_unit usage. > > Signed-off-by: Juergen Gross <jgr...@suse.com> > Reviewed-by: Dario Faggioli <dfaggi...@suse.com>
With just one additional note. > * This scheduler follows the Preemptive Global Earliest Deadline > First (EDF) > * theory in real-time field. > - * At any scheduling point, the VCPU with earlier deadline has > higher priority. > - * The scheduler always picks highest priority VCPU to run on a > feasible PCPU. > - * A PCPU is feasible if the VCPU can run on this PCPU and (the PCPU > is idle or > - * has a lower-priority VCPU running on it.) > + * At any scheduling point, the UNIT with earlier deadline has > higher priority. > From the real-time scheduling theory point of view, whether this really makes sense (i.e., it still makes it possible to provide real-time scheduling guarantees to guests, and if yes, how) has to be thought and considered. But this of course applies to the case when core-scheduling is actually used, which is not (at least by default) for now. Moreover, we're planning to make it possible to have it enabled on a per-pool basis, which means it will be possible to have sched_rt cpupools with core scheduling disabled. On this grounds, I'm ok with the changes to this scheduler. When the series is in, I'll add a note to this respect in some sched_rt related piece of documentation. Regards -- Dario Faggioli, Ph.D http://about.me/dario.faggioli Virtualization Software Engineer SUSE Labs, SUSE https://www.suse.com/ ------------------------------------------------------------------- <<This happens because _I_ choose it to happen!>> (Raistlin Majere)
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