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| author |   Peter Zijlstra <peterz@infradead.org> | 2013-11-07 14:43:43 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2014-01-13 13:41:50 +0100 |
| commit | fb00aca474405f4fa8a8519c3179fed722eabd83 (patch) | |
| tree | 8a779629a771dd3340d5a3ba0ba16b732b8de1c8 /include/linux/sched.h | |
| parent | sched/deadline: Add latency tracing for SCHED_DEADLINE tasks (diff) | |
| download | linux-dev-fb00aca474405f4fa8a8519c3179fed722eabd83.tar.xz linux-dev-fb00aca474405f4fa8a8519c3179fed722eabd83.zip | |
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>
Diffstat (limited to 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 158f4c2dd852..9ea15019a5b6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -16,6 +16,7 @@ struct sched_param { #include <linux/types.h> #include <linux/timex.h> #include <linux/jiffies.h> +#include <linux/plist.h> #include <linux/rbtree.h> #include <linux/thread_info.h> #include <linux/cpumask.h> @@ -1354,7 +1355,8 @@ struct task_struct { #ifdef CONFIG_RT_MUTEXES /* PI waiters blocked on a rt_mutex held by this task */ - struct plist_head pi_waiters; + struct rb_root pi_waiters; + struct rb_node *pi_waiters_leftmost; /* Deadlock detection and priority inheritance handling */ struct rt_mutex_waiter *pi_blocked_on; #endif |