linux-kernel - Re: [PATCH v12 06/31] x86,fs/resctrl: Use struct rdt_domain

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Message-ID: <aPqPzUqwOZ9o3DBK@agluck-desk3>
Date: Thu, 23 Oct 2025 13:27:57 -0700
From: "Luck, Tony" <tony.luck@...el.com>
To: Reinette Chatre <reinette.chatre@...el.com>
CC: Fenghua Yu <fenghuay@...dia.com>, Maciej Wieczor-Retman
	<maciej.wieczor-retman@...el.com>, Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>, Babu Moger <babu.moger@....com>, "Drew
 Fustini" <dfustini@...libre.com>, Dave Martin <Dave.Martin@....com>, Chen Yu
	<yu.c.chen@...el.com>, <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v12 06/31] x86,fs/resctrl: Use struct rdt_domain_hdr when
 reading counters

On Wed, Oct 22, 2025 at 09:17:54PM -0700, Reinette Chatre wrote:
> Hi Tony,
> 
> On 10/13/25 3:33 PM, Tony Luck wrote:
> > struct rmid_read contains data passed around to read event counts. Use the
> > generic domain header struct rdt_domain_hdr in struct rmid_read in order to
> > support other telemetry events' domains besides an L3 one. Adjust the code
> 
> "telemetry events" -> "monitoring events"?
> 
> > interacting with it to the new struct layout.
> 
> How does this justify the changes to resctrl_arch_rmid_read() and 
> resctrl_arch_cntr_read()? If these functions really needed to be changed in
> support of the change to struct rmid_read then resctrl_arch_reset_cntr()
> and resctrl_arch_reset_rmid() would need to be changed also, no? All four of
> these functions are called in the same way before this change but this patch
> inconsistently changes the calling convention of only two of them without any motivation.
> Seems like the resctrl_arch_rmid_read() change is sneaked in to support later
> reading of telemetry events while the change to resctrl_arch_cntr_read() is a
> remnant of a previous version of code in support of telemetry events?

These functions got caught up in this change, but it probably isn't
needed as they are L3 specific. I'll see how things look if I pull
the refactor of __mon_event_count() earlier so they can avoid this
unneeded churn.

-Tony