linux-kernel - Re: [PATCH v4 0/2] MIPS: CPS: Optimise delay CPU calibration and cluster helper function

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Message-ID: <aHfqLjX_Ml3AnjEH@alpha.franken.de>
Date: Wed, 16 Jul 2025 20:06:38 +0200
From: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To: Gregory CLEMENT <gregory.clement@...tlin.com>
Cc: Jiaxun Yang <jiaxun.yang@...goat.com>,
	Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>,
	Théo Lebrun <theo.lebrun@...tlin.com>,
	Tawfik Bayouk <tawfik.bayouk@...ileye.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 0/2] MIPS: CPS: Optimise delay CPU calibration and
 cluster helper function

On Fri, Jul 11, 2025 at 11:54:19AM +0200, Gregory CLEMENT wrote:
> This series allow booting faster by reusing the delay calibration
> across the CPU belonging of the same cluster. While doing it we now
> reuse the mips_cps_first_online_in_cluster() that we improve also.
> 
> This series enables faster booting by reusing delay calibration across
> CPUs within the same cluster. During this process, we reuse the
> improved mips_cps_first_online_in_cluster function.
> 
> With the introduction of this series, a configuration running 32 cores
> spread across two clusters sees a significant reduction in boot time
> by approximately 600 milliseconds.
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@...tlin.com>
> ---
> Changes in v4:
> - Fix build issue reported by kernel test robot <lkp@...el.com>
>   at https://lore.kernel.org/all/aG3AJ2XnH2JKOjzY@rli9-mobl/#t
> - Add reviewed-by tags from Jiaxun
> - Link to v3: https://lore.kernel.org/r/20250708-smp_calib-v3-0-6dabf01a7d9f@bootlin.com
> 
> Changes in v3:
> - Do not depend anymore of a Kconfig entry (suggested by Jiaxun).
> - cpumask for cluster filled now later in cps_prepare_cpus().
> - Patch 2 of the v2 has been removed.
> - Link to v2: https://lore.kernel.org/r/20250704-smp_calib-v2-0-bade7e9c0463@bootlin.com
> 
> Changes in v2:
> - Add a patch improving mips_cps_first_online_in_cluster()
> - Use mips_cps_first_online_in_cluster() in calibrate_delay_is_known()
>   as suggested by Jiaxun
> - Link to v1: https://lore.kernel.org/r/20250520-smp_calib-v1-1-cd04f0a78648@bootlin.com
> 
> ---
> Gregory CLEMENT (2):
>       MIPS: CPS: Improve mips_cps_first_online_in_cluster()
>       MIPS: CPS: Optimise delay CPU calibration for SMP
> 
>  arch/mips/include/asm/mips-cps.h |  4 +++-
>  arch/mips/include/asm/smp-cps.h  |  1 +
>  arch/mips/kernel/mips-cm.c       | 47 ++++++++++++++--------------------------
>  arch/mips/kernel/smp-cps.c       | 16 +++++++++++++-
>  4 files changed, 35 insertions(+), 33 deletions(-)

series applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]