linux-kernel - Re: [RFC][PATCH 07/11] sched: Stop setting PREEMPT

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Message-ID: <20150929114102.6c5f2402@gandalf.local.home>
Date:	Tue, 29 Sep 2015 11:41:02 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...nel.org, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, fweisbec@...il.com, oleg@...hat.com,
	umgwanakikbuti@...il.com, tglx@...utronix.de
Subject: Re: [RFC][PATCH 07/11] sched: Stop setting PREEMPT_ACTIVE

On Tue, 29 Sep 2015 11:28:32 +0200
Peter Zijlstra <peterz@...radead.org> wrote:

> Now that nothing tests for PREEMPT_ACTIVE anymore, stop setting it.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>


> @@ -3243,13 +3243,7 @@ asmlinkage __visible void __sched notrac
>  		return;
>  
>  	do {
> -		/*
> -		 * Use raw __prempt_count() ops that don't call function.
> -		 * We can't call functions before disabling preemption which
> -		 * disarm preemption tracing recursions.
> -		 */
> -		__preempt_count_add(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET);
> -		barrier();
> +		preempt_disable_notrace();
>  		/*
>  		 * Needs preempt disabled in case user_exit() is traced
>  		 * and the tracer calls preempt_enable_notrace() causing
> @@ -3259,8 +3253,7 @@ asmlinkage __visible void __sched notrac
>  		__schedule(true);
>  		exception_exit(prev_ctx);
>  
> -		barrier();
> -		__preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET);
> +		preempt_enable_no_resched_notrace();

Nice, you used the notrace variants for this function.

Reviewed-by: Steven Rostedt <rostedt@...dmis.org>

-- Steve

>  	} while (need_resched());
>  }
--
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