linux-kernel - Re: [PATCH]time: Optimize nohz idle enter

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Date:	Tue, 19 Jul 2016 10:47:37 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	"Gaurav Jindal (Gaurav Jindal)" <Gaurav.Jindal@...eadtrum.com>
cc:	"Sanjeev Yadav (Sanjeev Kumar Yadav)" <Sanjeev.Yadav@...eadtrum.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH]time: Optimize nohz idle enter 

On Thu, 14 Jul 2016, Gaurav Jindal (Gaurav Jindal) wrote:
> 
> tick_nohz_start_idle is called before checking the condition if the idle tick
> can be stopped. In case when can_stop_idle_tick returns 0, the function called
> is of no use thus a extra call doing nothing.
> 
> Shifting calling of function tick_nohz_start_idle inside the if condition makes
> sure that corresponding operations are done only if idle tick can be actually
> stopped. Observance for 1 minute on arm64 architecture shows that shifting code
> can prevent 1.5% of extra calls thus optimizing the idle call sequence.

Nice.

> Signed-off-by: gaurav jindal<gaurav.jindal@...eadtrum.com>
> Signed-off-by: sanjeev yadav<sanjeev.yadav@...eadtrum.com>

This SOB chain is wrong. Sanjeev did not send the patch and is not the
author. Please clarify.

Thanks,

	tglx