linux-kernel - Re: [PATCH v12 30/31] x86/resctrl: Add debugfs files to show telemetry aggregator status

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Message-ID: <caddeea9-78e2-47ae-8e55-3446ec423526@intel.com>
Date: Thu, 23 Oct 2025 10:50:46 -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>, Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v12 30/31] x86/resctrl: Add debugfs files to show
 telemetry aggregator status

Hi Tony,

On 10/13/25 3:33 PM, Tony Luck wrote:
> Each telemetry aggregator provides three status registers at the top
> end of MMIO space after all the per-RMID per-event counters:
> 
>   data_loss_count: This counts the number of times that this aggregator
>   failed to accumulate a counter value supplied by a CPU core.
> 
>   data_loss_timestamp: This is a "timestamp" from a free running
>   25MHz uncore timer indicating when the most recent data loss occurred.
> 
>   last_update_timestamp: Another 25MHz timestamp indicating when the
>   most recent counter update was successfully applied.
> 
> Create files in /sys/kernel/debug/resctrl/info/PERF_PKG_MON/x86_64/
> to display the value of each of these status registers for each aggregator
> in each enabled event group. The prefix for each file name describes
> the type of aggregator, which package it is located on, and an opaque
> instance number to provide a unique file name when there are multiple
> aggregators on a package.
> 
> The suffix is one of the three strings listed above. An example name is:
> 
> 	energy_pkg0_agg2_data_loss_count
> 
> These files are removed along with all other debugfs entries by the
> call to debugfs_remove_recursive() in resctrl_exit().
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---

(nit: please fix that style issue reported by checkpatch.pl for
intel_aet_add_debugfs())

| Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette