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    SubjectRe: [RFC PATCH] topology: Represent clusters of CPUs within a die.
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    Le 19/10/2020 à 14:50, Peter Zijlstra a écrit :
    > On Mon, Oct 19, 2020 at 01:32:26PM +0100, Jonathan Cameron wrote:
    >> On Mon, 19 Oct 2020 12:35:22 +0200
    >> Peter Zijlstra <peterz@infradead.org> wrote:
    >>> I'm confused by all of this. The core level is exactly what you seem to
    >>> want.
    >> It's the level above the core, whether in an multi-threaded core
    >> or a single threaded core. This may correspond to the level
    >> at which caches are shared (typically L3). Cores are already well
    >> represented via thread_siblings and similar. Extra confusion is that
    >> the current core_siblings (deprecated) sysfs interface, actually reflects
    >> the package level and ignores anything in between core and
    >> package (such as die on x86)
    > That seems wrong. core-mask should be whatever cores share L3. So on a
    > Intel Core2-Quad (just to pick an example) you should have 4 CPU in a
    > package, but only 2 CPUs for the core-mask.
    >
    > It just so happens that L3 and package were the same for a long while in
    > x86 land, although recent chips started breaking that trend.
    >
    > And I know nothing about the core-mask being depricated; it's what the
    > scheduler uses. It's not going anywhere.


    Only the sysfs filenames are deprecated:

    thread_siblings -> core_cpus

    core_siblings -> package_cpus

    New names reflect better what has been implemented/documented in the
    past (core_siblings=package_cpus are processors with same physical
    package id). And that's indeed different from the core-mask you are
    talking about above with Core2-Quad (that one has never been exposed
    anywhere in sysfs, except in the L3 cpumap).

    Brice


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