[LITMUS^RT] new patches and new branch

[Björn Brandenburg]

Hi everyone,

a quick heads-up: I've merged four patches into staging (see below). Some of them stem from our OSPERT project and fix latency issues when measuring latencies with cyclictest.

Further, there's a new branch called  'rebased-3.0'.

	https://github.com/LITMUS-RT/litmus-rt/commits/rebased-3.0

This branch contains the same features / patches as staging, but has been rebased cleanly on top of v3.0 (based on an earlier patch series by Felipe). This is the first step towards porting LITMUS^RT to a new kernel version, and eventually to PREEMPT_RT. Please check it out if you have some time.

Thanks,
Björn


commit c1f183501ce70a510a4d9ab98595500904f33705
Author: Bjoern Brandenburg <bbb at mpi-sws.org>
Date:   Sat Jun 8 18:22:35 2013 +0200

    Augment rt_task() with is_realtime()
    
    Whenever the kernel checks for rt_task() to avoid delaying real-time
    tasks, we want it to also not delay LITMUS^RT tasks.  Hence, most
    calls to rt_task() should be matched by an equivalent call to
    is_realtime(). This patch fixes a few places where this was missing.
    Notably, this affects the impolementation of select(), which uses
    timer_slack_ns when setting up timers for non-real-time tasks.

commit 5e5d22d9724a5bc11d459c4f08d475941c2482ed
Author: Bjoern Brandenburg <bbb at mpi-sws.org>
Date:   Sat Jun 8 17:58:41 2013 +0200

    Disable timer slack for LITMUS^RT tasks in nanosleep()
    
    As with SCHED_FIFO/SCHED_RR tasks, artificial latency is not
    desired...

commit 12dab1d22770b58ae174c46dc292a4dfb0e01452
Author: Bjoern Brandenburg <bbb at mpi-sws.org>
Date:   Sat Jun 8 12:22:59 2013 +0200

    GSN-EDF: link tasks to local CPU if it is idle
    
    If a task is released on a CPU that is idle, then it is pointless to
    send an IPI to another CPU just to schedule the newly released task.
    This patch changes check_for_preemptions() to prefer the local CPU
    first if it is idle.

commit b46ddf5d187d603f72389ac047a99e80edb6285d
Author: Bjoern Brandenburg <bbb at mpi-sws.org>
Date:   Thu May 30 14:34:22 2013 +0200

    Use vmalloc() to allocate Feather-Trace buffers
    
    Allocating contiguous buffers with kmalloc() is subject to severe
    maximum size limits. For Feather-Trace to work, we don't actually need
    *physically* contiguous memory; virtually contiguous memory is
    sufficient. By switching to vmalloc(), the code gets simpler and we
    can support much larger buffers.
    
    For convenience, this patch also adds a configuration option for
    the desired Feather-Trace buffer size and increases the default
    size.