]> git.karo-electronics.de Git - karo-tx-linux.git/commit
rtmutex: Turn the plist into an rb-tree
authorPeter Zijlstra <peterz@infradead.org>
Thu, 7 Nov 2013 13:43:43 +0000 (14:43 +0100)
committerIngo Molnar <mingo@kernel.org>
Mon, 13 Jan 2014 12:41:50 +0000 (13:41 +0100)
commitfb00aca474405f4fa8a8519c3179fed722eabd83
tree8a779629a771dd3340d5a3ba0ba16b732b8de1c8
parentaf6ace764d03900524e9b1ac621a1c520ee49fc6
rtmutex: Turn the plist into an rb-tree

Turn the pi-chains from plist to rb-tree, in the rt_mutex code,
and provide a proper comparison function for -deadline and
-priority tasks.

This is done mainly because:
 - classical prio field of the plist is just an int, which might
   not be enough for representing a deadline;
 - manipulating such a list would become O(nr_deadline_tasks),
   which might be to much, as the number of -deadline task increases.

Therefore, an rb-tree is used, and tasks are queued in it according
to the following logic:
 - among two -priority (i.e., SCHED_BATCH/OTHER/RR/FIFO) tasks, the
   one with the higher (lower, actually!) prio wins;
 - among a -priority and a -deadline task, the latter always wins;
 - among two -deadline tasks, the one with the earliest deadline
   wins.

Queueing and dequeueing functions are changed accordingly, for both
the list of a task's pi-waiters and the list of tasks blocked on
a pi-lock.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-again-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1383831828-15501-10-git-send-email-juri.lelli@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
include/linux/init_task.h
include/linux/rtmutex.h
include/linux/sched.h
kernel/fork.c
kernel/futex.c
kernel/locking/rtmutex-debug.c
kernel/locking/rtmutex.c
kernel/locking/rtmutex_common.h
kernel/sched/core.c