[LITMUS^RT] prop/edf-early-release

[Glenn Elliott]

Hi All,

I've run into a number of applications where early job releasing would be useful.  Specifically, this is in the context of interrupt handling threads, non-root PGM graph nodes, and bandwidth servers.  Tasks must be explicitly configured for early releasing: prop/edf-early-release adds a new field to the task params.  Note that early releasing is only supported by EDF.

The patch is simple and unobtrusive, but I understand if this isn't desired for mainline.  I've posted the patch to github.

From the commit:

commit 60d107ca171413cc5f765e51aa0c4cd6848e139e
Author: Glenn Elliott <gelliott at cs.unc.edu>
Date:   Tue Mar 5 20:03:04 2013 -0500

    EDF schedulers: Support early job releasing.
    
    This patch allows a task to request early releasing
    via rt_task parameters to sys_set_task_rt_param().
    Note that early releasing can easily peg your CPUs
    since early-releasing tasks never suspend to wait for
    their next job. As such, early releasing is really
    only useful in the context of implementing bandwidth
    servers, interrupt handling threads (or any thread that
    spends most of its time waiting for an event), or
    short-lived computations. If early releasing pegs your
    CPUs, then you probably shouldn't be using it.

-Glenn