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Date: Thu, 26 Oct 2017 15:41:36 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: cj.chengjian@huawei.com, tglx@linutronix.de, hpa@zytor.com,
        linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
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Cc: linux-tip-commits@vger.kernel.org
Subject: Re: [tip:sched/core] sched/idle: Micro-optimize the idle loop
Message-ID: <20171026134136.GR3165@worktop.lehotels.local>
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On Thu, Oct 26, 2017 at 02:31:34AM -0700, tip-bot for Cheng Jian wrote:
> After patch (execution in loop):
> 	872:       0f ae e8                lfence

> ARM64:

> After patch (execution in loop):
> 	c84:       d5033d9f        dsb     ld

> @@ -225,7 +226,7 @@ static void do_idle(void)
>  		check_pgt_cache();
>  		rmb();

I never could find a reason for that rmb() to exist, it also lacks a
clarifying comment.

We should perhaps attempt removing that...