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    SubjectRe: [PATCH 0/5] SUBCPUSETS: a resource control functionality using CPUSETS

    > Well, I suspect I don't understand yet.
    > Nice picture though - that gives me some idea what you mean.
    > Do notice that the basic rule of cpu_exclusive cpusets is that their
    > CPUs don't overlap their siblings. Your Cpusets 1, 2, and 3 seem to be
    > marked cpu_exclusive in your picture, but all contain the same CPUs 2
    > and 3, overlapping each other.

    Yes, I know the current design of cpu_exclusive.
    I just thought if I could enhance cpu_exclusive to cover a group of
    cpusets to make the hierarchy as flat as possible.

    > I'm guessing what you are trying to draw is:
    > Tasks on CPUs 0 and 1 have no resource control limits.

    I thought CPU 1 could have resource control limits.

    > Tasks on CPUs 2 and 3 have resource control limits specifying
    > what percentage of the CPUs 2 and 3 is available to them.
    > I might draw my solution to that as:

    I understand your idea clearly, which is essentially the same as
    Korosawa's design. Your design looks very straight and I have
    no objection to it.

    My only concern is that it would become harder to control resources
    between CPUSET 1a,1b and 1c if some processes are assigned to CPUSET 1
    directly. But I just get an idea that it would be OK if CPUSET 1 can
    have meter_cpu=1 to share the resources.

    > +-----------------------------------+
    > | |
    > sched domain A sched domain B
    > cpus: 0, 1 cpus: 2, 3
    > cpu_exclusive=1 cpu_exclusive=1
    > meter_cpu=0 meter_cpu=0
    > |
    > +----------------+----------------+
    > | | |
    > cpus: 2, 3 cpus: 2, 3 cpus: 2, 3
    > cpu_exclusive=0 cpu_exclusive=0 cpu_exclusive=0
    > meter_cpu=1 meter_cpu=1 meter_cpu=1
    > meter_cpu_* meter_cpu_* meter_cpu_*
    > The meter_cpu_* files in each of Cpusets 1a, 1b, and 1c control what
    > proportion of the CPU resources in that Cpuset can be used by the tasks
    > in that Cpuset.
    > If meter_cpu is false (0) then the meter_cpu_* files do not appear,
    > which is equivalent to allowing 100% of the CPUs in that Cpuset to
    > be used by the tasks in that Cpuset (and descendents, of course.)
    > Don't forget - this all seems like it has significant mission overlap
    > with CKRM. I hate to repeat this, but the relation of your work to
    > CKRM needs to be understood before I am likely to agree to accepting
    > your work into the kernel (not that my acceptance is required; you
    > really just need Linus to agree, though he of course considers the
    > positions of others to some inscrutable degree.)


    Hirokazu Takahashi.
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