linux-kernel - Re: [PATCH v11 06/10] fs/resctrl: Add user interface to enable/disable io

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Message-ID: <43506b9c-5ad7-4871-8a24-11e71380321d@intel.com>
Date: Mon, 3 Nov 2025 11:05:56 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <tony.luck@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <corbet@....net>, <Dave.Martin@....com>, <james.morse@....com>,
	<x86@...nel.org>, <hpa@...or.com>, <akpm@...ux-foundation.org>,
	<paulmck@...nel.org>, <rdunlap@...radead.org>, <pmladek@...e.com>,
	<kees@...nel.org>, <arnd@...db.de>, <fvdl@...gle.com>, <seanjc@...gle.com>,
	<pawan.kumar.gupta@...ux.intel.com>, <xin@...or.com>,
	<thomas.lendacky@....com>, <sohil.mehta@...el.com>, <jarkko@...nel.org>,
	<chang.seok.bae@...el.com>, <ebiggers@...gle.com>,
	<elena.reshetova@...el.com>, <ak@...ux.intel.com>,
	<mario.limonciello@....com>, <perry.yuan@....com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<peternewman@...gle.com>, <feng.tang@...ux.alibaba.com>
Subject: Re: [PATCH v11 06/10] fs/resctrl: Add user interface to
 enable/disable io_alloc feature

Hi Babu,

On 10/30/25 10:15 AM, Babu Moger wrote:

...

> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
> index 108995640ca5..89e856e6892c 100644
> --- a/Documentation/filesystems/resctrl.rst
> +++ b/Documentation/filesystems/resctrl.rst
> @@ -152,6 +152,29 @@ related to allocation:
>  			"not supported":
>  			      Support not available for this resource.
>  
> +		The feature can be modified by writing to the interface, for example:
> +
> +		To enable:
> +			# echo 1 > /sys/fs/resctrl/info/L3/io_alloc
> +
> +		To disable:
> +			# echo 0 > /sys/fs/resctrl/info/L3/io_alloc
> +

Above examples are missing the '::' that will format them as fixed width text blocks
used for these shell examples.

> +		The underlying implementation may reduce resources available to
> +		general (CPU) cache allocation. See architecture specific notes
> +		below. Depending on usage requirements the feature can be enabled
> +		or disabled.
> +
> +		On AMD systems, io_alloc feature is supported by the L3 Smart
> +		Data Cache Injection Allocation Enforcement (SDCIAE). The CLOSID for
> +		io_alloc is the highest CLOSID supported by the resource. When
> +		io_alloc is enabled, the highest CLOSID is dedicated to io_alloc and
> +		no longer available for general (CPU) cache allocation. When CDP is
> +		enabled, io_alloc routes I/O traffic using the highest CLOSID allocated
> +		for the instruction cache (CDP_CODE), making this CLOSID no longer
> +		available for general (CPU) cache allocation for both the CDP_CODE
> +		and CDP_DATA resources.
> +
>  Memory bandwidth(MB) subdirectory contains the following files
>  with respect to allocation:
>  

With the doc formatting fixed:
| Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette