linux-kernel - Re: [PATCH v19 15/20] x86/resctrl: Pass two extra arguments to resctrl_arch_rmid

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Date: Thu, 30 May 2024 13:24:18 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com>, Maciej
 Wieczor-Retman <maciej.wieczor-retman@...el.com>, Peter Newman
	<peternewman@...gle.com>, James Morse <james.morse@....com>, Babu Moger
	<babu.moger@....com>, Drew Fustini <dfustini@...libre.com>, Dave Martin
	<Dave.Martin@....com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v19 15/20] x86/resctrl: Pass two extra arguments to
 resctrl_arch_rmid_read()

Hi Tony,

On 5/28/24 3:20 PM, Tony Luck wrote:
> For backwards compatibility on Sub-NUMA Cluster (SNC) systems the legacy
> files in the mon_L3_XX directories must report the sum of data from each
> SNC node sharing that L3 cache instance.
> 
> To make this possible, pass the "sumdomains" and "ci" fields from
> rmid_read structure as extra arguments to resctrl_arch_rmid_read().
> 
> Note that the call from check_limbo() never operates on a "sum" basis,
> so pass sumdomains=false, ci=NULL.

Why is passing "sumdomains" necessary? Can it not be inferred from
domain being NULL?

Reinette