linux-kernel - Re: [PATCH v7 3/6] cpufreq: powernv: Remove cpu_to_chip

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Message-ID: <20160128081103.GB13654@in.ibm.com>
Date:	Thu, 28 Jan 2016 13:41:03 +0530
From:	Gautham R Shenoy <ego@...ux.vnet.ibm.com>
To:	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
Cc:	linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
	rjw@...ysocki.net, viresh.kumar@...aro.org,
	linux-pm@...r.kernel.org, pc@...ibm.com, anton@...ba.org,
	ego@...ux.vnet.ibm.com, shreyas@...ux.vnet.ibm.com,
	bsingharora@...il.com, mpe@...erman.id.au
Subject: Re: [PATCH v7 3/6] cpufreq: powernv: Remove cpu_to_chip_id() from
 hot-path

On Thu, Jan 28, 2016 at 12:55:38PM +0530, Shilpasri G Bhat wrote:
> cpu_to_chip_id() does a DT walk through to find out the chip id by
> taking a contended device tree lock. This adds an unnecessary overhead
> in a hot path. So instead of calling cpu_to_chip_id() everytime cache
> the chip ids for all cores in the array 'core_to_chip_map' and use it
> in the hotpath.
> 
> Reported-by: Anton Blanchard <anton@...ba.org>
> Signed-off-by: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>

Reviewed-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com>

--
Thanks and Regards
gautham.