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    SubjectRe: [Devel] Re: [RFC] Virtualization steps

    >> Why do you think it can not be measured? It either can be, or it is too
    >> low to be measured reliably (a fraction of a per cent or so).
    > Well, for instance the fair CPU scheduling overhead is so tiny it may as
    > well not be there in the VServer patch. It's just a per-vserver TBF
    > that feeds back into the priority (and hence timeslice length) of the
    > process. ie, you get "CPU tokens" which deplete as processes in your
    > vserver run and you either get a boost or a penalty depending on the
    > level of the tokens in the bucket. This doesn't provide guarantees, but
    > works well for many typical workloads.
    I wonder what is the value of it if it doesn't do guarantees or QoS?
    In our experiments with it we failed to observe any fairness. So I
    suppose the only goal of this is too make sure that maliscuios user want
    consume all the CPU power, right?

    > How does your fair scheduler work? Do you just keep a runqueue for each
    > vps?
    we keep num_online_cpus runqueues per VPS.
    Fairs scheduler is some kind of SFQ like algorithm which selects VPS to
    be scheduled, than standart linux scheduler selects a process in a VPS
    runqueues to run.

    > To be honest, I've never needed to determine whether its overhead is 1%
    > or 0.01%, it would just be a meaningless benchmark anyway :-). I know
    > it's "good enough for me".
    Sure! We feel the same, but people like numbers :)

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