linux-kernel - Re: [PATCH RT 1/2] x86/kconfig: Use ticket spinlocks for -rt

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Message-ID: <20181004140846.uerpx7txvx7pj6yc@linutronix.de>
Date:   Thu, 4 Oct 2018 16:08:46 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Daniel Wagner <daniel.wagner@...mens.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        linux-rt-users <linux-rt-users@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Carsten Emde <C.Emde@...dl.org>,
        John Kacur <jkacur@...hat.com>,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Julia Cartwright <julia@...com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH RT 1/2] x86/kconfig: Use ticket spinlocks for -rt

On 2018-10-04 15:46:21 [+0200], Daniel Wagner wrote:
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 6df130a37d41..21f9418d850f 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -42,7 +42,7 @@ config X86
>  	select ARCH_USE_BUILTIN_BSWAP
>  	select ARCH_USE_CMPXCHG_LOCKREF		if X86_64
>  	select ARCH_USE_QUEUED_RWLOCKS
> -	select ARCH_USE_QUEUED_SPINLOCKS
> +	select ARCH_USE_QUEUED_SPINLOCKS	if !PREEMPT_RT_FULL
>  	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
>  	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
>  	select ARCH_WANT_FRAME_POINTERS

I would argue, that RT exposes a problem and we should not limit it to
RT only. Anyone?

Sebastian