linux-kernel - Re: [PATCH v16 26/34] fs/resctrl: Provide interface to update the event configurations

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Message-ID: <9887b44b-4813-47b8-86aa-ba72de3c96da@intel.com>
Date: Wed, 30 Jul 2025 13:05:41 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <corbet@....net>, <tony.luck@...el.com>,
	<james.morse@....com>, <tglx@...utronix.de>, <mingo@...hat.com>,
	<bp@...en8.de>, <dave.hansen@...ux.intel.com>
CC: <Dave.Martin@....com>, <x86@...nel.org>, <hpa@...or.com>,
	<akpm@...ux-foundation.org>, <paulmck@...nel.org>, <rostedt@...dmis.org>,
	<Neeraj.Upadhyay@....com>, <david@...hat.com>, <arnd@...db.de>,
	<fvdl@...gle.com>, <seanjc@...gle.com>, <jpoimboe@...nel.org>,
	<pawan.kumar.gupta@...ux.intel.com>, <xin@...or.com>,
	<manali.shukla@....com>, <tao1.su@...ux.intel.com>, <sohil.mehta@...el.com>,
	<kai.huang@...el.com>, <xiaoyao.li@...el.com>, <peterz@...radead.org>,
	<xin3.li@...el.com>, <kan.liang@...ux.intel.com>,
	<mario.limonciello@....com>, <thomas.lendacky@....com>, <perry.yuan@....com>,
	<gautham.shenoy@....com>, <chang.seok.bae@...el.com>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<peternewman@...gle.com>, <eranian@...gle.com>
Subject: Re: [PATCH v16 26/34] fs/resctrl: Provide interface to update the
 event configurations

Hi Babu,

On 7/25/25 11:29 AM, Babu Moger wrote:
> When "mbm_event" counter assignment mode is supported, users can modify

"supported" -> "enabled"?

> the event configuration by writing to the 'event_filter' resctrl file.
> The event configurations for mbm_event mode are located in
> /sys/fs/resctrl/info/L3_MON/event_configs/.
> 
> Update the assignments of all CTRL_MON and MON resource groups when the
> event configuration is modified.
> 
> Example:
> $ mount -t resctrl resctrl /sys/fs/resctrl
> 
> $ cd /sys/fs/resctrl/
> 
> $ cat info/L3_MON/event_configs/mbm_local_bytes/event_filter
>   local_reads,local_non_temporal_writes,local_reads_slow_memory
> 
> $ echo "local_reads,local_non_temporal_writes" >
>   info/L3_MON/event_configs/mbm_total_bytes/event_filter
> 
> $ cat info/L3_MON/event_configs/mbm_total_bytes/event_filter
>   local_reads,local_non_temporal_writes
> 
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---

...

> ---
>  Documentation/filesystems/resctrl.rst |  12 +++
>  fs/resctrl/internal.h                 |   4 +
>  fs/resctrl/monitor.c                  | 114 ++++++++++++++++++++++++++
>  fs/resctrl/rdtgroup.c                 |   3 +-
>  4 files changed, 132 insertions(+), 1 deletion(-)
> 

...

> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
> index e082d8718199..e2e3fc0c5fab 100644
> --- a/fs/resctrl/internal.h
> +++ b/fs/resctrl/internal.h
> @@ -409,11 +409,15 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
>  				  struct mon_evt *mevt);
>  int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d,
>  		 struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
> +void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt);

Is there some code ordering issue in monitor.c? Looks like this function
is only used in monitor.c so seeing it here is unexpected.

>  
>  void *rdt_kn_parent_priv(struct kernfs_node *kn);
>  
>  int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq, void *v);
>  
> +ssize_t event_filter_write(struct kernfs_open_file *of, char *buf, size_t nbytes,
> +			   loff_t off);
> +
>  #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
>  int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
>  
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index fa5f63126682..8efbeb910f77 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c

...

> @@ -1193,3 +1264,46 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
>  		rdtgroup_free_unassign_cntr(r, d, rdtgrp, mevt);
>  	}
>  }
> +
> +/*
> + * rdtgroup_update_cntr_event - Update the counter assignments for the event
> + *				in a group.
> + * @r:		Resource to which update needs to be done.
> + * @rdtgrp:	Resctrl group.
> + * @evtid:	MBM monitor event.
> + */
> +static void rdtgroup_update_cntr_event(struct rdt_resource *r, struct rdtgroup *rdtgrp,
> +				       enum resctrl_event_id evtid)
> +{
> +	struct rdt_mon_domain *d;
> +	int cntr_id;
> +
> +	list_for_each_entry(d, &r->mon_domains, hdr.list) {
> +		cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
> +		if (cntr_id >= 0)
> +			resctrl_arch_config_cntr(r, d, evtid, rdtgrp->mon.rmid,
> +						 rdtgrp->closid, cntr_id, true);

Should non-arch MBM state be reset here?

> +	}
> +}
> +

Reinette