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

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Message-ID: <93bd2525-d98d-4fbe-8e98-ff252d17f5e0@arm.com>
Date: Fri, 28 Feb 2025 19:54:25 +0000
From: James Morse <james.morse@....com>
To: Reinette Chatre <reinette.chatre@...el.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 Reinette,

On 20/02/2025 05:54, Reinette Chatre wrote:
> 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.

>> 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?

Sure, it can't hurt.


Thanks,

James