sched/deadline: Add SCHED_DEADLINE inheritance logic
authorDario Faggioli <raistlin@linux.it>
Thu, 7 Nov 2013 13:43:44 +0000 (14:43 +0100)
committerIngo Molnar <mingo@kernel.org>
Mon, 13 Jan 2014 12:42:56 +0000 (13:42 +0100)
commit2d3d891d3344159d5b452a645e355bbe29591e8b
treeab7c4ef00b48d68efa2d57cabf8c3c86160f2406
parentfb00aca474405f4fa8a8519c3179fed722eabd83
sched/deadline: Add SCHED_DEADLINE inheritance logic

Some method to deal with rt-mutexes and make sched_dl interact with
the current PI-coded is needed, raising all but trivial issues, that
needs (according to us) to be solved with some restructuring of
the pi-code (i.e., going toward a proxy execution-ish implementation).

This is under development, in the meanwhile, as a temporary solution,
what this commits does is:

 - ensure a pi-lock owner with waiters is never throttled down. Instead,
   when it runs out of runtime, it immediately gets replenished and it's
   deadline is postponed;

 - the scheduling parameters (relative deadline and default runtime)
   used for that replenishments --during the whole period it holds the
   pi-lock-- are the ones of the waiting task with earliest deadline.

Acting this way, we provide some kind of boosting to the lock-owner,
still by using the existing (actually, slightly modified by the previous
commit) pi-architecture.

We would stress the fact that this is only a surely needed, all but
clean solution to the problem. In the end it's only a way to re-start
discussion within the community. So, as always, comments, ideas, rants,
etc.. are welcome! :-)

Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
[ Added !RT_MUTEXES build fix. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1383831828-15501-11-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
include/linux/sched.h
include/linux/sched/rt.h
kernel/fork.c
kernel/locking/rtmutex.c
kernel/locking/rtmutex_common.h
kernel/sched/core.c
kernel/sched/deadline.c
kernel/sched/sched.h
kernel/trace/trace_sched_wakeup.c