linux-kernel - Re: [PATCH] sched/core: make "Preemption disabled at" message more useful

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Date:	Wed, 27 Jul 2016 14:25:50 +0200
From:	Vegard Nossum <vegard.nossum@...cle.com>
To:	Ingo Molnar <mingo@...nel.org>,
	Vegard Nossum <vegard.nossum@...il.com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Rusty Russel <rusty@...tcorp.com.au>
Subject: Re: [PATCH] sched/core: make "Preemption disabled at" message more
 useful

On 07/27/2016 12:38 PM, Ingo Molnar wrote:
> * Vegard Nossum <vegard.nossum@...il.com> wrote:
>> I'm assuming you want to declare and initialise preempt_disable_ip at
>> once here, but it generates slightly worse code since it dereferences
>> current->preempt_disable_ip in the "fast path" (i.e. a sleeping
>> function is NOT called from an invalid context).
>
> Could you please add a likely() branch to see whether GCC will delay the
> initialization?
>
> The 4 #ifdefs were really ugly, so yes, it would be nice to at least reduce them
> to 2.

How about this?


Vegard

View attachment "0001-sched-core-make-Preemption-disabled-at-message-more-.patch" of type "text/x-patch" (4506 bytes)