Date: Sat, 2 Apr 2016 09:23:37 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Byungchul Park <byungchul.park@lge.com>,
        Chris Metcalf <cmetcalf@ezchip.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Luiz Capitulino <lcapitulino@redhat.com>,
        Christoph Lameter <cl@linux.com>,
        "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
        Mike Galbraith <efault@gmx.de>, Rik van Riel <riel@redhat.com>,
        Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 3/4] sched: Optimize tick periodic cpu load updates
Message-ID: <20160402072337.GF2906@worktop>
References: <1459516987-15745-1-git-send-email-fweisbec@gmail.com>
 <1459516987-15745-4-git-send-email-fweisbec@gmail.com>
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On Fri, Apr 01, 2016 at 03:23:06PM +0200, Frederic Weisbecker wrote:
> Don't bother with the whole pending tickless cpu load machinery if
> we run a tick periodic kernel. That's less job for the CPU on ticks.

Again, the changelog really could use help. Is this a pure optimization
patch? If so, do you have numbers?

> +++ b/kernel/sched/sched.h
> @@ -585,8 +585,10 @@ struct rq {
>  #endif
>  	#define CPU_LOAD_IDX_MAX 5
>  	unsigned long cpu_load[CPU_LOAD_IDX_MAX];
> +#ifdef CONFIG_NO_HZ_COMMON
> +# ifdef CONFIG_SMP

I'm not a fan of this #ifdef indenting and nothing near there uses this
style, so please don't introduce it here.

>  	unsigned long last_load_update_tick;
> -#ifdef CONFIG_NO_HZ_COMMON
> +# endif
>  	u64 nohz_stamp;
>  	unsigned long nohz_flags;
>  #endif
> -- 
> 2.7.0
>