linux-kernel - Re: [PATCH v1 29/31] fs/resctrl: Add boiler plate for external resctrl code

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Message-ID: <ZhlgCIhEqdTCS6pW@e133380.arm.com>
Date: Fri, 12 Apr 2024 17:23:36 +0100
From: Dave Martin <Dave.Martin@....com>
To: Babu Moger <Babu.Moger@....com>
Cc: James Morse <james.morse@....com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Fenghua Yu <fenghua.yu@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	H Peter Anvin <hpa@...or.com>,
	Reinette Chatre <reinette.chatre@...el.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>
Subject: Re: [PATCH v1 29/31] fs/resctrl: Add boiler plate for external
 resctrl code

Hi Babu,

[see below]

On Thu, Apr 11, 2024 at 10:42:48AM -0700, Reinette Chatre wrote:
> Hi Dave,
> 
> On 4/11/2024 7:27 AM, Dave Martin wrote:
> > On Mon, Apr 08, 2024 at 08:41:04PM -0700, Reinette Chatre wrote:
> >> Hi James,
> >>
> >> On 3/21/2024 9:51 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
> >>> depend on this.
> >>>
> >>> Signed-off-by: James Morse <james.morse@....com>

[...]

> >>> diff --git a/fs/resctrl/Kconfig b/fs/resctrl/Kconfig
> >>> new file mode 100644
> >>> index 000000000000..36a1ddbe6c21
> >>> --- /dev/null
> >>> +++ b/fs/resctrl/Kconfig
> >>
> >> Could you please review the contents of this file for
> >> appropriate line length and consistent tab usage?
> > 
> > Noted.
> > 
> >>> @@ -0,0 +1,23 @@
> >>> +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
> >>> +	  Resctrl is a filesystem interface
> >>> +	  to control allocation and
> >>> +	  monitoring of system resources
> >>> +	  used by the CPUs.
> > 
> > (Not quite a haiku, but I don't know how many syllables "resctrl"
> > counts as...)
> > 
> > Since this is the Kconfig user's primary knob for enabling resctrl,
> > maybe flesh this out and make it a bit more generic and newbie-friendly?
> > Something like:
> > 
> > 	  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).
> 
> Nit: We should double check with AMD how they want to refer to their
> feature. Their contribution to the resctrl docs used the term you provide
> but their spec uses PQOS.

Babu, do you have a view on this?

Initially I just pasted this across from the existing text in
resctrl.rst and arch/x86/Kconfig.

Looking at the AMD's spec though, I'd probably follow Reinette's
suggestion and go for:

	[...] AMD's Platform Quality of Service (PQOS)

but I'm happy to take your recommendation if you think AMD would prefer
different text here.

Cheers
---Dave