linux-kernel - Re: [BUG] [ tip/sched/core ] System unresponsive after booting

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Date:	Wed, 15 Jan 2014 14:28:02 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Peter Zijlstra <peterz@...radead.org>,
	Michael wang <wangyun@...ux.vnet.ibm.com>
CC:	raistlin@...ux.it, juri.lelli@...il.com,
	Ingo Molnar <mingo@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] [ tip/sched/core ] System unresponsive after booting

On 01/15/2014 12:30 PM, Peter Zijlstra wrote:
> On Wed, Jan 15, 2014 at 05:25:55PM +0800, Michael wang wrote:
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index 0326c06..bf4a6ed 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -3464,6 +3464,10 @@ int sched_setscheduler(struct task_struct *p, int
>> policy,
>>                  .sched_policy   = policy,
>>                  .sched_priority = param->sched_priority
>>          };
>> +
>> +       if (fair_policy(policy))
>> +               attr.sched_nice = PRIO_TO_NICE(attr.sched_priority);
>> +
>>          return __sched_setscheduler(p, &attr, true);
>>   }
>>   EXPORT_SYMBOL_GPL(sched_setscheduler);
>> @@ -3494,6 +3498,10 @@ int sched_setscheduler_nocheck(struct task_struct
>> *p, int policy,
>>                  .sched_policy   = policy,
>>                  .sched_priority = param->sched_priority
>>          };
>> +
>> +       if (fair_policy(policy))
>> +               attr.sched_nice = PRIO_TO_NICE(attr.sched_priority);
>> +
>>          return __sched_setscheduler(p, &attr, false);
>>   }
>
> That seems wrong; the manpage confirms, from sched_setscheduler(2):
>
>         For processes scheduled under one of the normal scheduling
>         policies (SCHED_OTHER, SCHED_IDLE, SCHED_BATCH), sched_priority
>         is not used in scheduling decisions (it must  be  speci‐ fied as
>         0).
>
> That said; we should probably preserve the nice value, which with the
> current code we reset to 0.

I tried this patch also but it does not solve the issue.


> ---
>   kernel/sched/core.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 0326c06953eb..f3abbb7dae62 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3462,7 +3462,8 @@ int sched_setscheduler(struct task_struct *p, int policy,
>   {
>   	struct sched_attr attr = {
>   		.sched_policy   = policy,
> -		.sched_priority = param->sched_priority
> +		.sched_priority = param->sched_priority,
> +		.sched_nice	= PRIO_TO_NICE(p->static_prio),
>   	};
>   	return __sched_setscheduler(p, &attr, true);
>   }
> @@ -3492,7 +3493,8 @@ int sched_setscheduler_nocheck(struct task_struct *p, int policy,
>   {
>   	struct sched_attr attr = {
>   		.sched_policy   = policy,
> -		.sched_priority = param->sched_priority
> +		.sched_priority = param->sched_priority,
> +		.sched_nice	= PRIO_TO_NICE(p->static_prio),
>   	};
>   	return __sched_setscheduler(p, &attr, false);
>   }
>


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