[lkml]   [2008]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: current linux-2.6.git: cpusets completely broken

    * Linus Torvalds <> wrote:

    > The thing is, we should fix the top level code to never even
    > _consider_ an invalid CPU as a target, and that in turn should mean
    > that all the other code should be able to just totally ignore CPU
    > hotplug events.

    agreed. We thought we could get away by hiding the "is the CPU dead"
    information in existing data structures (by shaping sched domains to
    never lead to a dead CPU) - but this method has proven itself fragile
    via a series of bugs.

    It was one micro-optimization one too many. We should just accept the
    fact that the current model is not maintainable and add your extra (and
    trivial) cpu_active_map layer that protects against migrating to CPUs
    that are going down. [we'll basically introduce a "going down" state
    inbetween 'online' and 'offline']

    And this will get rid of some other fragile trickery - because from that
    point on we dont have to be super-careful about the whole sequence of
    manipulating sched domains anymore. Cpusets can do whatever it wants, it
    wont be able to break hotplug+scheduling - and that's important for any
    functionality that is not used by default.

    [ I dont think Dmitry will disagree with this notion all that much, it's
    just that his personal limit for calling an algorithm unmaintainable
    is probably a lot higher than normal :-) ]


     \ /
      Last update: 2008-07-13 19:45    [W:0.021 / U:6.728 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site