Skip to content
  • Dario Faggioli's avatar
    sched: Add new scheduler syscalls to support an extended scheduling parameters ABI · d50dde5a
    Dario Faggioli authored
    
    
    Add the syscalls needed for supporting scheduling algorithms
    with extended scheduling parameters (e.g., SCHED_DEADLINE).
    
    In general, it makes possible to specify a periodic/sporadic task,
    that executes for a given amount of runtime at each instance, and is
    scheduled according to the urgency of their own timing constraints,
    i.e.:
    
     - a (maximum/typical) instance execution time,
     - a minimum interval between consecutive instances,
     - a time constraint by which each instance must be completed.
    
    Thus, both the data structure that holds the scheduling parameters of
    the tasks and the system calls dealing with it must be extended.
    Unfortunately, modifying the existing struct sched_param would break
    the ABI and result in potentially serious compatibility issues with
    legacy binaries.
    
    For these reasons, this patch:
    
     - defines the new struct sched_attr, containing all the fields
       that are necessary for specifying a task in the computational
       model described above;
    
     - defines and implements the new scheduling related syscalls that
       manipulate it, i.e., sched_setattr() and sched_getattr().
    
    Syscalls are introduced for x86 (32 and 64 bits) and ARM only, as a
    proof of concept and for developing and testing purposes. Making them
    available on other architectures is straightforward.
    
    Since no "user" for these new parameters is introduced in this patch,
    the implementation of the new system calls is just identical to their
    already existing counterpart. Future patches that implement scheduling
    policies able to exploit the new data structure must also take care of
    modifying the sched_*attr() calls accordingly with their own purposes.
    
    Signed-off-by: default avatarDario Faggioli <raistlin@linux.it>
    [ Rewrote to use sched_attr. ]
    Signed-off-by: default avatarJuri Lelli <juri.lelli@gmail.com>
    [ Removed sched_setscheduler2() for now. ]
    Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/1383831828-15501-3-git-send-email-juri.lelli@gmail.com
    
    
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    d50dde5a