linux-kernel - Re: [PATCH v13 15/32] fs/resctrl: Cleanup as L3 is no longer the only monitor resource

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Message-ID: <cc70a3ed-2b07-492b-b18f-5338524cf522@intel.com>
Date: Wed, 12 Nov 2025 20:05:14 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.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>, Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v13 15/32] fs/resctrl: Cleanup as L3 is no longer the only
 monitor resource

Hi Tony,

I do not see how the subject matches this patch. How about something like:
"fs/resctrl: Emphasize that L3 monitoring resource is required for summing domains"

On 10/29/25 9:20 AM, Tony Luck wrote:
> The feature to sum event data across multiple domains supports systems
> with Sub-NUMA Cluster (SNC) mode enabled. The top-level monitoring files
> in each "mon_L3_XX" directory provide the sum of data across all SNC
> nodes sharing an L3 cache instance while the "mon_sub_L3_YY" sub-directories
> provide the event data of the individual nodes.
> 
> SNC is only associated with the L3 resource and domains and as a result
> the flow handling the sum of event data implicitly assumes it is
> working with the L3 resource and domains.
> 
> Reading of telemetry events do not require to sum event data so this
> feature can remain dedicated to SNC and keep the implicit assumption
> of working with the L3 resource and domains.
> 
> Add a WARN to where the implicit assumption of working with the L3 resource
> is made and add comments on how the structure controlling the event sum
> feature is used.
> 
> Suggested-by: Reinette Chatre <reinette.chatre@...el.com>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---

| Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette