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    SubjectRe: [RFC PATCH V2 13/22] x86/intel_rdt: Support schemata write - pseudo-locking core
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    Hi Thomas,

    On 2/27/2018 11:52 AM, Reinette Chatre wrote:
    > On 2/27/2018 2:36 AM, Thomas Gleixner wrote:
    >> Let's assume its real,
    >> so you could do the following:
    >>
    >> mkdir group <- acquires closid
    >> echo locksetup > mode <- Creates 'lockarea' file
    >> echo L2:0 > lockarea
    >> echo 'L2:0=0xf' > schemata
    >> echo locked > mode <- locks down all files, does the lock setup
    >> and drops closid
    >>
    >> That would solve quite some of the other issues as well. Hmm?
    >
    > At this time the resource group, represented by a resctrl directory, is
    > tightly associated with the closid. I'll take a closer look at what it
    > will take to separate them.
    >
    > Could you please elaborate on the purpose of the "lockarea" file? It
    > does seem to duplicate the information in the schemata written in the
    > subsequent line.
    >
    > If we do go this route then it seems that there would be one
    > pseudo-locked region per resource group, not multiple ones as I had in
    > my examples above.

    Actually, this need not be true. It could be possible for administrator
    to pseudo-lock two regions at once. For example,

    mkdir group
    echo locksetup > mode
    echo 'L2:0=0xf;1=0xf' > schemata

    This could have two pseudo-locked regions associated with a single
    resource group. This does complicate the usage of the "size" file even
    more though since the plan was to have a single "size" file associated
    with a resource group it is not intuitive how it should describe
    multiple pseudo-locked regions. I added the "size" file originally to
    help users of the pseudo-locking interface where a single pseudo-locked
    region existed in a directory. All information to compute the size
    themselves are available to users, perhaps I can add pseudo-code to
    compute the size from available information to the documentation?

    Reinette



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