linux-kernel - Re: [PATCH 2/2] sched: readjust the load whenever task

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Message-Id: <48805C06.BA47.005A.0@novell.com>
Date:	Fri, 18 Jul 2008 07:01:58 -0600
From:	"Gregory Haskins" <ghaskins@...ell.com>
To:	"Peter Zijlstra" <peterz@...radead.org>
Cc:	<mingo@...e.hu>, <rostedt@...dmis.org>,
	<linux-kernel@...r.kernel.org>, <linux-rt-users@...r.kernel.org>,
	<stable@...r.kernel.org>
Subject: Re: [PATCH 2/2] sched: readjust the load whenever
	task_setprio()is invoked

>>> On Fri, Jul 18, 2008 at  8:43 AM, in message <1216384984.28405.36.camel@...ns>,
Peter Zijlstra <peterz@...radead.org> wrote: 
> On Thu, 2008-07-03 at 15:37 -0600, Gregory Haskins wrote:
>> The load may change with the priority, so be sure to recompute its value.
>> 
>> Signed-off-by: Gregory Haskins <ghaskins@...ell.com>
>> CC: Peter Zijlstra <peterz@...radead.org>
>> CC: Ingo Molnar <mingo@...e.hu>
> 
> Right, but in this case we'd need to do the dec/inc load game again
> because otherwise we'll skew stuff - see the previuos mail on how
> dequeue_task() doesn't actually do that.
> 
> Also, it looks like current mainline still has this issue.
> 
> OTOH - since prio boosting is a temporal feature, not changing the load
> isn't too bad, we ought to get back to where we came from pretty
> quickly.

Yeah, I agree.  This issue probably didn't actually matter much in practice.

It just "looked" wrong, so I figured I'd fix it ;)

-Greg

> 
> 
> 
>> ---
>> 
>>  kernel/sched.c |    1 +
>>  1 files changed, 1 insertions(+), 0 deletions(-)
>> 
>> diff --git a/kernel/sched.c b/kernel/sched.c
>> index b046754..c3f41b9 100644
>> --- a/kernel/sched.c
>> +++ b/kernel/sched.c
>> @@ -4637,6 +4637,7 @@ void task_setprio(struct task_struct *p, int prio)
>>  		p->sched_class = &fair_sched_class;
>>  
>>  	p->prio = prio;
>> +	set_load_weight(p);
>>  
>>  //	trace_special_pid(p->pid, __PRIO(oldprio), PRIO(p));
>>  	prev_resched = _need_resched();
>> 



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