linux-kernel - Re: [PATCH v10 2/8] x86/resctrl: Prepare for per-CTRL_MON group mba

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Message-ID: <cd0f7219-4b4d-4297-aa02-5ad5efda4fa0@intel.com>
Date: Tue, 26 Nov 2024 10:30:57 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com>, "Peter
 Newman" <peternewman@...gle.com>, Jonathan Corbet <corbet@....net>,
	<x86@...nel.org>
CC: James Morse <james.morse@....com>, Jamie Iles <quic_jiles@...cinc.com>,
	Babu Moger <babu.moger@....com>, Randy Dunlap <rdunlap@...radead.org>,
	"Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>,
	<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v10 2/8] x86/resctrl: Prepare for per-CTRL_MON group
 mba_MBps control

Hi Tony,

On 11/22/24 3:58 PM, Tony Luck wrote:
> Resctrl uses local memory bandwidth event as input to the feedback
> loop when the mba_MBps mount option is used. This means that this
> mount option cannot be used on systems that only support monitoring
> of total bandwidth.
> 
> Prepare to allow users to choose the input event independently for
> each CTRL_MON group by adding a global variable "mba_mbps_default_event"
> used to set the default event for each CTRL_MON group, and a new
> field "mba_mbps_event" in struct rdtgroup to track which event is
> used for each CTRL_MON group.
> 
> Notes:
> 1) Both of these are only used when the user mounts the filesystm with

filesystm -> filesystem

> the "mba_MBps" option.
> 2) Only check for support of local bandwidth event when initializing
> mba_mbps_default_event. Support for total bandwidth event can be added
> after other routines in resctrl have been updated to handle total
> bandwidth event.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---

...

> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 2b198ef95e1e..2d42d69ddbe5 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -65,6 +65,17 @@ static void rdtgroup_destroy_root(void);
>  
>  struct dentry *debugfs_resctrl;
>  
> +/*
> + * Memory bandwidth monitoring event to use for the
> + * default CTRL_MON group and each new CTRL_MON
> + * group created by the user.
> + * Only relevant when the filesystem is mounted
> + * with the "mba_MBps" option so it does not matter
> + * that it remains uninitialized on systems that do
> + * not support the "mba_MBps" option.
> + */

These lines are trimmed unnecessarily. Could you please make use of the 80 columns available?

With typo and style change:
| Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette