lkml.org 
[lkml]   [2014]   [Oct]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] sched/deadline: clear dl_entity params when setscheduling to different class
ping,

于 10/8/14, 8:32 PM, Wanpeng Li 写道:
> Hi Juri,
>
> 于 9/19/14, 5:22 PM, Juri Lelli 写道:
>> When a task is using SCHED_DEADLINE and the user setschedules it to a
>> different
>> class its sched_dl_entity static parameters are not cleaned up. This
>> causes a
>> bug if the user sets it back to SCHED_DEADLINE with the same
>> parameters again.
>> The problem resides in the check we perform at the very beginning of
>> dl_overflow():
>>
>> if (new_bw == p->dl.dl_bw)
>> return 0;
>>
>> This condition is met in the case depicted above, so the function
>> returns and
>> dl_b->total_bw is not updated (the p->dl.dl_bw is not added to it).
>> After this,
>
> As you know there is no static parameter clear before this patch, so
> if p->dl.dl_bw will decrease from dl_b->total_bw when the user
> setschedules to a different class instead of dl?
>
> Regards,
> Wanpeng Li
>
>> admission control is broken.
>>
>> This patch fixes the thing, properly clearing static parameters for a
>> task
>> that ceases to use SCHED_DEADLINE.
>>
>> Reported-by: Daniele Alessandrelli <daniele.alessandrelli@gmail.com>
>> Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
>> Reported-by: Vincent Legout <vincent@legout.info>
>> Tested-by: Luca Abeni <luca.abeni@unitn.it>
>> Signed-off-by: Juri Lelli <juri.lelli@arm.com>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Juri Lelli <juri.lelli@gmail.com>
>> Cc: Dario Faggioli <raistlin@linux.it>
>> Cc: Michael Trimarchi <michael@amarulasolutions.com>
>> Cc: Fabio Checconi <fchecconi@gmail.com>
>> Cc: linux-kernel@vger.kernel.org
>> ---
>> kernel/sched/core.c | 19 +++++++++++++++----
>> kernel/sched/deadline.c | 2 ++
>> kernel/sched/sched.h | 3 +++
>> 3 files changed, 20 insertions(+), 4 deletions(-)
>>
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index ec1a286..581a429 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -1776,6 +1776,20 @@ int wake_up_state(struct task_struct *p,
>> unsigned int state)
>> }
>> /*
>> + * This function clears the sched_dl_entity static params.
>> + */
>> +void __dl_clear_params(struct task_struct *p)
>> +{
>> + struct sched_dl_entity *dl_se = &p->dl;
>> +
>> + dl_se->dl_runtime = 0;
>> + dl_se->dl_deadline = 0;
>> + dl_se->dl_period = 0;
>> + dl_se->flags = 0;
>> + dl_se->dl_bw = 0;
>> +}
>> +
>> +/*
>> * Perform scheduler related setup for a newly forked process p.
>> * p is forked by current.
>> *
>> @@ -1799,10 +1813,7 @@ static void __sched_fork(unsigned long
>> clone_flags, struct task_struct *p)
>> RB_CLEAR_NODE(&p->dl.rb_node);
>> hrtimer_init(&p->dl.dl_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>> - p->dl.dl_runtime = p->dl.runtime = 0;
>> - p->dl.dl_deadline = p->dl.deadline = 0;
>> - p->dl.dl_period = 0;
>> - p->dl.flags = 0;
>> + __dl_clear_params(p);
>> INIT_LIST_HEAD(&p->rt.run_list);
>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>> index 255ce13..4a51b14 100644
>> --- a/kernel/sched/deadline.c
>> +++ b/kernel/sched/deadline.c
>> @@ -1569,6 +1569,8 @@ static void switched_from_dl(struct rq *rq,
>> struct task_struct *p)
>> if (hrtimer_active(&p->dl.dl_timer) && !dl_policy(p->policy))
>> hrtimer_try_to_cancel(&p->dl.dl_timer);
>> + __dl_clear_params(p);
>> +
>> #ifdef CONFIG_SMP
>> /*
>> * Since this might be the only -deadline task on the rq,
>> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
>> index 579712f..4890484 100644
>> --- a/kernel/sched/sched.h
>> +++ b/kernel/sched/sched.h
>> @@ -126,6 +126,9 @@ struct rt_bandwidth {
>> u64 rt_runtime;
>> struct hrtimer rt_period_timer;
>> };
>> +
>> +void __dl_clear_params(struct task_struct *p);
>> +
>> /*
>> * To keep the bandwidth of -deadline tasks and groups under control
>> * we need some place where:
>

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2014-10-21 14:41    [W:0.131 / U:0.396 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site