linux-kernel - Re: [PATCH v21 13/18] x86/resctrl: Handle removing directories in Sub-NUMA Cluster (SNC) mode

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Date: Tue, 25 Jun 2024 16:31:38 -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 v21 13/18] x86/resctrl: Handle removing directories in
 Sub-NUMA Cluster (SNC) mode

Hi Tony,

On 6/21/24 3:38 PM, Tony Luck wrote:
> In SNC mode there are multiple subdirectories in each L3 level monitor
> directory (one for each SNC node). If all the CPUs in an SNC node are
> taken offline, just remove the SNC directory for that node. In
> non-SNC mode, or when the last SNC node directory is removed,
> remove the L3 monitor directory.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c | 39 +++++++++++++++++++++-----
>   1 file changed, 32 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 2591a6876232..14482d88b68c 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -3008,20 +3008,45 @@ static int mon_addfile(struct kernfs_node *parent_kn, const char *name,
>   
>   /*
>    * Remove all subdirectories of mon_data of ctrl_mon groups
> - * and monitor groups with given domain id.
> + * and monitor groups for the given domain. In SNC mode just

I do not think we want the Intel architecture specific "SNC" to be
a "mode" of resctrl fs. That means all architectures need a "SNC mode".
How about something like (please feel free to improve):
	Remove files and directories containing "sum" of domain data
	when last domain being summed is removed.


With mention of "SNC mode" removed:
| Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette