lkml.org 
[lkml]   [2016]   [Jun]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC][PATCH 3/8] sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update
Hi,

On 07/06/16 21:56, Peter Zijlstra wrote:
> From: Xunlei Pang <xlpang@redhat.com>
>
> Currently dl tasks will actually return at the very beginning
> of rt_mutex_adjust_prio_chain() in !detect_deadlock cases:
>
> if (waiter->prio == task->prio) {
> if (!detect_deadlock)
> goto out_unlock_pi; // out here
> else
> requeue = false;
> }
>
> As the deadline value of blocked deadline tasks(waiters) without
> changing their sched_class(thus prio doesn't change) never changes,
> this seems reasonable, but it actually misses the chance of updating
> rt_mutex_waiter's "dl_runtime(period)_copy" if a waiter updates its
> deadline parameters(dl_runtime, dl_period) or boosted waiter changes
> to !deadline class.
>
> Thus, force deadline task not out by adding the !dl_prio() condition.
>
> [peterz: I should introduce more task state comparators like
> rt_mutex_waiter_less, all PI prio comparisons already have this DL
> exception, except this one]
>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Juri Lelli <juri.lelli@arm.com>
> Signed-off-by: Xunlei Pang <xlpang@redhat.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Link: http://lkml.kernel.org/r/1460633827-345-7-git-send-email-xlpang@redhat.com
> ---
> kernel/locking/rtmutex.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -488,7 +488,7 @@ static int rt_mutex_adjust_prio_chain(st
> * enabled we continue, but stop the requeueing in the chain
> * walk.
> */
> - if (waiter->prio == task->prio) {
> + if (waiter->prio == task->prio && !dl_task(task)) {

Right. Do we want a rt_mutex_waiter_equal() helper? As I think the
comment in the changelog was also saying?

Best,

- Juri

\
 
 \ /
  Last update: 2016-06-14 13:21    [W:0.255 / U:0.232 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site