linux-kernel - Re: [PATCH v1 17/31] x86/resctrl: Move mbm_cfg_mask to struct rdt

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Message-ID: <Zhfwzh4sHvTYyTJ1@e133380.arm.com>
Date: Thu, 11 Apr 2024 15:16:46 +0100
From: Dave Martin <Dave.Martin@....com>
To: Reinette Chatre <reinette.chatre@...el.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>, 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>
Subject: Re: [PATCH v1 17/31] x86/resctrl: Move mbm_cfg_mask to struct
 rdt_resource

On Mon, Apr 08, 2024 at 08:21:24PM -0700, Reinette Chatre wrote:
> Hi James,
> 
> On 3/21/2024 9:50 AM, James Morse wrote:
> > The mbm_cfg_mask field lists the bits that user-space can set when
> > configuring an event. This value is output via the last_cmd_status
> > file.
> > 
> > Once the filesystem parts of resctrl are moved to live in /fs/, the
> > struct rdt_hw_resource is inaccessible to the filesystem code. Because
> > this value is output to user-space, it has to be accessible to the
> > filesystem code.
> > 
> > Move it to struct rdt_resource.
> > 
> > Signed-off-by: James Morse <james.morse@....com>
> 
> ..
> 
> > diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> > index 975b80102fbe..8a7367d1ce45 100644
> > --- a/include/linux/resctrl.h
> > +++ b/include/linux/resctrl.h
> > @@ -140,6 +140,8 @@ struct resctrl_membw {
> >   * @format_str:		Per resource format string to show domain value
> >   * @evt_list:		List of monitoring events
> >   * @fflags:		flags to choose base and info files
> > + * @mbm_cfg_mask:	Bandwidth sources that can be tracked when Bandwidth
> > + *			Monitoring Event Configuration (BMEC) is supported.

[...]

> Reinette
> 
> BMEC is an AMD term. If MPAM is planning to use this member then this comment
> should be made generic.

MPAM can (at least) filter reads and/or writes, and it looks like James
is expecting to support this.

However, it probably does make sense to keep the comments neutral in a
common header.

Would the following work?

	* @ mbm_cfg_mask:	Arch-specific event configuration flags



I think that's broad enough to cover all bases, but I'll wait for your
response.

Cheers
---Dave