Subject: Re: [PATCH v6 2/5] cpufreq: powernv: Remove cpu_to_chip_id() from hot-path

From: Balbir Singh <[email-masked]>
Date: Sat, 23 Jan 2016 19:59:20 +1100

On Fri, 22 Jan 2016 12:49:02 +0530
Shilpasri G Bhat <[email-masked]> 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 <[email-masked]>
> Signed-off-by: Shilpasri G Bhat <[email-masked]>
> Reviewed-by: Gautham R. Shenoy <[email-masked]>

snip

Does the core_to_chip_map need to be updated/refreshed on/after/ a
cpu (core) hotplug? I presume id's don't change

Balbir