linux-kernel - Re: [PATCH v6 40/42] fs/resctrl: Add boiler plate for external resctrl code

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Message-ID: <67ef5b80-cafb-4e04-a66a-5f361a3d4f85@intel.com>
Date: Wed, 19 Feb 2025 21:54:54 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, H Peter Anvin <hpa@...or.com>, Babu Moger
	<Babu.Moger@....com>, <shameerali.kolothum.thodi@...wei.com>, "D Scott
 Phillips OS" <scott@...amperecomputing.com>, <carl@...amperecomputing.com>,
	<lcherian@...vell.com>, <bobo.shaobowang@...wei.com>,
	<tan.shaopeng@...itsu.com>, <baolin.wang@...ux.alibaba.com>, Jamie Iles
	<quic_jiles@...cinc.com>, Xin Hao <xhao@...ux.alibaba.com>,
	<peternewman@...gle.com>, <dfustini@...libre.com>, <amitsinght@...vell.com>,
	David Hildenbrand <david@...hat.com>, Rex Nie <rex.nie@...uarmicro.com>,
	"Dave Martin" <dave.martin@....com>, Koba Ko <kobak@...dia.com>, Shanker
 Donthineni <sdonthineni@...dia.com>, Shaopeng Tan
	<tan.shaopeng@...fujitsu.com>, "Tony Luck" <tony.luck@...el.com>
Subject: Re: [PATCH v6 40/42] fs/resctrl: Add boiler plate for external
 resctrl code

Hi James,

On 2/7/25 10:18 AM, James Morse wrote:
> Add Makefile and Kconfig for fs/resctrl. Add ARCH_HAS_CPU_RESCTRL
> for the common parts of the resctrl interface and make X86_CPU_RESCTRL
> select this.
> 
> Adding an include of asm/resctrl.h to linux/resctrl.h allows the
> /fs/resctrl files to switch over to using this header instead.
> 
> Co-developed-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Carl Worth <carl@...amperecomputing.com> # arm64
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> ---

...

> diff --git a/fs/resctrl/Kconfig b/fs/resctrl/Kconfig
> new file mode 100644
> index 000000000000..229ca71a8258
> --- /dev/null
> +++ b/fs/resctrl/Kconfig
> @@ -0,0 +1,37 @@
> +config RESCTRL_FS
> +	bool "CPU Resource Control Filesystem (resctrl)"
> +	depends on ARCH_HAS_CPU_RESCTRL
> +	select KERNFS
> +	select PROC_CPU_RESCTRL if PROC_FS
> +	help
> +	  Some architectures provide hardware facilities to group tasks and
> +	  monitor and control their usage of memory system resources such as
> +	  caches and memory bandwidth.  Examples of such facilities include
> +	  Intel's Resource Director Technology (Intel(R) RDT) and AMD's
> +	  Platform Quality of Service (AMD QoS).
> +
> +	  If your system has the necessary support and you want to be able to
> +	  assign tasks to groups and manipulate the associated resource
> +	  monitors and controls from userspace, say Y here to get a mountable
> +	  'resctrl' filesystem that lets you do just that.
> +
> +	  If nothing mounts or prods the 'resctrl' filesystem, resource
> +	  controls and monitors are left in a quiescent, permissive state.
> +
> +	  On architectures where this can be disabled independently, it is
> +	  safe to say N.
> +
> +	  See <file:Documentation/arch/x86/resctrl.rst> for more information.
> +
> +config RESCTRL_FS_PSEUDO_LOCK
> +	bool
> +	help
> +	  Software mechanism to pin data in a cache portion using
> +	  micro-architecture specific knowledge.
> +
> +config RESCTRL_RMID_DEPENDS_ON_CLOSID
> +	bool
> +	help
> +	  Enabled by the architecture when the RMID values depend on the CLOSID.
> +	  This causes the CLOSID allocator to search for CLOSID with clean
> +	  RMID.

With RESCTRL_FS_PSEUDO_LOCK and RESCTRL_RMID_DEPENDS_ON_CLOSID appearing at
same level as RESCTRL_FS all three configs "depends on MISC_FILESYSTEMS".
Should RESCTRL_FS_PSEUDO_LOCK and RESCTRL_RMID_DEPENDS_ON_CLOSID
"depends on RESCTRL_FS" instead?

Reinette