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Date:   Wed, 22 Jan 2020 10:56:22 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Alex Kogan <alex.kogan@oracle.com>
Cc:     linux@armlinux.org.uk, mingo@redhat.com, will.deacon@arm.com,
        arnd@arndb.de, longman@redhat.com, linux-arch@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        tglx@linutronix.de, bp@alien8.de, hpa@zytor.com, x86@kernel.org,
        guohanjun@huawei.com, jglauber@marvell.com,
        steven.sistare@oracle.com, daniel.m.jordan@oracle.com,
        dave.dice@oracle.com
Subject: Re: [PATCH v8 5/5] locking/qspinlock: Introduce the shuffle
 reduction optimization into CNA
Message-ID: <20200122095622.GS14914@hirez.programming.kicks-ass.net>
References: <20191230194042.67789-1-alex.kogan@oracle.com>
 <20191230194042.67789-6-alex.kogan@oracle.com>
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On Mon, Dec 30, 2019 at 02:40:42PM -0500, Alex Kogan wrote:
> @@ -251,8 +281,11 @@ __always_inline u32 cna_pre_scan(struct qspinlock *lock,
>  	struct cna_node *cn = (struct cna_node *)node;
>  
>  	cn->pre_scan_result =
> -		cn->intra_count == intra_node_handoff_threshold ?
> -			FLUSH_SECONDARY_QUEUE : cna_scan_main_queue(node, node);
> +		(node->locked <= 1 && probably(SHUFFLE_REDUCTION_PROB_ARG)) ?
> +			PASS_LOCK_IMMEDIATELY :
> +			cn->intra_count == intra_node_handoff_threshold ?
> +				FLUSH_SECONDARY_QUEUE :
> +				cna_scan_main_queue(node, node);
>  
>  	return 0;
>  }

Let me just, once again, remind people that the Linux Kernel is not part
of the Obfuscated C code contest.

> Reviewed-by: Steve Sistare <steven.sistare@oracle.com>

Seriously, in what universe is that actually readable code? Steve quick,
say what it does.