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    Subject[RFC 0/12][PATCH] SCHED_DEADLINE (new version of SCHED_EDF)
    Hi Peter, Hi all,

    Given all the comments and feedback we got, here it is the new version
    of our EDF patch, this time in a split series. :-)

    Special thanks to all the one that gave us any kind of suggestion,
    especially during last RTLWS in Dresden.

    The rationale/motivation for the new scheduler is the same of the first
    e-mail (, thus I only add some new and
    (I think) interesting links:
    - Ericsson posting about SCHED_EDF/DEADLINE

    - The slides we presented at RTLWS in Dresden:

    - Luca Abeni's presentation about using deadline based reservation
    schedulers for IRQ-Threads:

    Moreover, we moved the project on, therefore:

    I am also setting up right now the Wiki section, where you can find some
    more detailed usage instructions, examples and overhead estimation:

    Git repositories are up and running, and ready at:
    git:// sched-deadline

    git:// sched-devel-deadline

    (preempt-rt [*])
    git:// rt-deadline

    The new project homepage is

    Here the main changes we did, following what many of you --and mainly
    Peter-- suggested:
    - name changed from SCHED_EDF to SCHED_DEADLINE

    - SCHED_DEADLINE has higher priority than SCHED_FIFO/SCHED_RR

    - flags added in sched_param_ex to signal deadline misses
    (in case of utilization > 100%) and/or budget overruns
    - new sched_*_ex prototypes, with a len field to accomodate the size of
    sched_param_ex, trying to avoid further ABI issues if it changes

    - new syscall sched_wait_interval added. It behaves like clock_nanosleep
    but, for a SCHED_DEADLINE task, it also represent the end of the
    current instance (sched_yield no longer needed)

    - on fork, child starts but with 0 bandwidth (i.e., it does not start! :-D)

    - bug fixing :)

    Any feedback and contribution is welcome.

    Many thanks,

    Dario Faggioli
    Claudio Scordino
    Michael Trimarchi

    [*] porting toward preempt-rt is work in progress. Code is there, but we
    are testing and fixing it, with the help of Luca and Nicola from
    Trento... So don't consider it as the final version!

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