Re: [TIP/SCHED/DEVEL PATCH v3 4/6] sched: add sched_class->needs_post_schedule() member

From: Gregory Haskins <gregory.haskins@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Gregory Haskins <ghaskins@novell.com>,
	mingo@elte.hu, peterz@infradead.org,
	linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org,
	npiggin@suse.de
Subject: Re: [TIP/SCHED/DEVEL PATCH v3 4/6] sched: add sched_class->needs_post_schedule() member
Date: Thu, 04 Sep 2008 16:36:04 -0400	[thread overview]
Message-ID: <48C046B4.1030706@gmail.com> (raw)
In-Reply-To: <alpine.DEB.1.10.0809041634580.3849@gandalf.stny.rr.com>

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Steven Rostedt wrote:
> On Thu, 4 Sep 2008, Gregory Haskins wrote:
>   
>> diff --git a/kernel/sched.c b/kernel/sched.c
>> index af4c6fa..ddc3877 100644
>> --- a/kernel/sched.c
>> +++ b/kernel/sched.c
>> @@ -2525,6 +2525,14 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
>>  {
>>  	struct mm_struct *mm = rq->prev_mm;
>>  	long prev_state;
>> +#ifdef CONFIG_SMP
>> +	int post_schedule = 0;
>> +
>> +	if (current->sched_class->needs_post_schedule) {
>> +		BUG_ON(!current->sched_class->post_schedule);
>>     
>
> The only one to ever hit this BUG_ON is a kernel developer creating a new
> sched class. Since they should be smart enough to figure out why they get 
> a segv later on, we really don't need it. Because this BUG_ON is also in 
> a hot path, I strongly suggest nuking it.
>   
Ack.  Will do a respin after you review the last few patches.

-Greg


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