linux-kernel - Re: [PATCH v7 12/31] fs/resctrl: Make event details accessible to functions when reading events

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Message-ID: <6a69ff53-5c3a-45d5-904e-dfd3f58b6472@intel.com>
Date: Fri, 25 Jul 2025 16:27:36 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, 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>, Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v7 12/31] fs/resctrl: Make event details accessible to
 functions when reading events

Hi Tony,

On 7/11/25 4:53 PM, Tony Luck wrote:
> All details about a monitor event are kept in the mon_evt structure.
> Upper levels of code only provide the event id to lower levels.

<newline to separate context from problem> 

> This will become a problem when new attributes are added to the
> mon_evt structure.

Please be specific what is meant with "This" (is it that all details are
kept in the mon_evt structure or that upper levels only provide event id?)
as well as what "a problem" refers to.

> 
> Change the mon_data and rmid_read structures to hold a pointer
> to the mon_evt structure instead of just taking a copy of the
> event id.
> 
> No functional change.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  fs/resctrl/internal.h    | 10 +++++-----
>  fs/resctrl/ctrlmondata.c | 16 ++++++++--------
>  fs/resctrl/monitor.c     | 17 +++++++++--------
>  fs/resctrl/rdtgroup.c    |  6 +++---
>  4 files changed, 25 insertions(+), 24 deletions(-)
> 
> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
> index e4f06f700063..ef3ec2a4860f 100644
> --- a/fs/resctrl/internal.h
> +++ b/fs/resctrl/internal.h
> @@ -76,7 +76,7 @@ extern struct mon_evt mon_event_all[QOS_NUM_EVENTS];
>   * struct mon_data - Monitoring details for each event file.
>   * @list:            Member of the global @mon_data_kn_priv_list list.
>   * @rid:             Resource id associated with the event file.
> - * @evtid:           Event id associated with the event file.
> + * @evt:             Event structure associated with the event file.
>   * @sum:             Set for RDT_RESOURCE_L3 when event must be summed
>   *                   across multiple domains.
>   * @domid:           When @sum is zero this is the domain to which
> @@ -90,7 +90,7 @@ extern struct mon_evt mon_event_all[QOS_NUM_EVENTS];
>  struct mon_data {
>  	struct list_head	list;
>  	enum resctrl_res_level	rid;
> -	enum resctrl_event_id	evtid;
> +	struct mon_evt		*evt;
>  	int			domid;
>  	bool			sum;
>  };
> @@ -103,7 +103,7 @@ struct mon_data {
>   * @r:	   Resource describing the properties of the event being read.
>   * @hdr:   Header of domain that the counter should be read from. If NULL then sum all
>   *	   domains in @r sharing L3 @ci.id
> - * @evtid: Which monitor event to read.
> + * @evt:   Event associated with the event file.

There is not always an event file involved when struct rmid_read is used to
read a counter. I believe that the original description is sufficient.

>   * @first: Initialize MBM counter when true.
>   * @ci_id: Cacheinfo id for L3. Only set when @hdr is NULL. Used when summing domains.
>   * @err:   Error encountered when reading counter.
> @@ -117,7 +117,7 @@ struct rmid_read {
>  	struct rdtgroup		*rgrp;
>  	struct rdt_resource	*r;
>  	struct rdt_domain_hdr	*hdr;
> -	enum resctrl_event_id	evtid;
> +	struct mon_evt		*evt;
>  	bool			first;
>  	unsigned int		ci_id;
>  	int			err;

Reinette