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    SubjectRe: [ckrm-tech] [RFC] Resource Management - Infrastructure choices
    Paul Menage wrote:
    > On 10/30/06, Pavel Emelianov <> wrote:
    >> > Debated:
    >> > - syscall vs configfs interface
    >> 1. One of the major configfs ideas is that lifetime of
    >> the objects is completely driven by userspace.
    >> Resource controller shouldn't live as long as user
    >> want. It "may", but not "must"! As you have seen from
    >> our (beancounters) patches beancounters disapeared
    >> as soon as the last reference was dropped.
    > Why is this an important feature for beancounters? All the other
    > resource control approaches seem to prefer having userspace handle
    > removing empty/dead groups/containers.

    That's functionality user may want. I agree that some users
    may want to create some kind of "persistent" beancounters, but
    this must not be the only way to control them. I like the way
    TUN devices are done. Each has TUN_PERSIST flag controlling
    whether or not to destroy device right on closing. I think that
    we may have something similar - a flag BC_PERSISTENT to keep
    beancounters with zero refcounter in memory to reuse them.


    >> 2. Having configfs as the only interface doesn't alow
    >> people having resource controll facility w/o configfs.
    >> Resource controller must not depend on any "feature".
    > Why is depending on a feature like configfs worse than depending on a
    > feature of being able to extend the system call interface?

    Because configfs is a _feature_, while system calls interface is
    a mandatory part of a kernel. Since "resource beancounters" is a
    core thing it shouldn't depend on "optional" kernel stuff. E.g.
    procfs is the way userspace gets information about running tasks,
    but disabling procfs doesn't disable such core functionality
    as fork-ing and execve-ing.

    Moreover, I hope you agree that beancounters can't be made as
    module. If so user will have to built-in configfs, and thus
    CONFIG_CONFIGFS_FS essentially becomes "bool", not a "tristate".

    I have nothing against using configfs as additional, optional
    interface, but I do object using it as the only window inside
    BC world.

    >> > - Interaction of resource controllers, containers and cpusets
    >> > - Should we support, for instance, creation of resource
    >> > groups/containers under a cpuset?
    >> > - Should we have different groupings for different resources?
    >> This breaks the idea of groups isolation.
    > That's fine - some people don't want total isolation. If we're looking
    > for a solution that fits all the different requirements, then we need
    > that flexibility. I agree that the default would probably want to be
    > that the groupings be the same for all resource controllers /
    > subsystems.

    Hm... OK, I don't mind although don't see any reasonable use of it.
    Thus we add one more point to our "agreement" list

    - all resource groups are independent
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      Last update: 2006-10-31 09:39    [W:0.025 / U:7.944 seconds]
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