Re: [PATCH v6 20/30] x86,fs/resctrl: Fill in details of Clearwater Forest events

[Reinette Chatre <reinette.chatre@intel.com>]

Hi Tony,

On 6/26/25 9:49 AM, Tony Luck wrote:
> Clearwater Forest supports two energy related telemetry events
> and seven perf style events. The counters are arranged in per-RMID
> blocks like this:
> 
> 	MMIO offset:0x00 Counter for RMID 0 Event 0
> 	MMIO offset:0x08 Counter for RMID 0 Event 1
> 	MMIO offset:0x10 Counter for RMID 0 Event 2
> 	MMIO offset:0x18 Counter for RMID 1 Event 0
> 	MMIO offset:0x20 Counter for RMID 1 Event 1
> 	MMIO offset:0x28 Counter for RMID 1 Event 2
> 	...

It is a bit unexpected that this patch is (a) specific to Clearwater Forest,
(b) it is noted that Clearwater Forest has _two_ energy related events and
_seven_ perf related events ... but then the example is for a layout with
_three_ events?

> 
> Define these events in the file system code and add the events
> to the event_group structures.
> 
> PMT_EVENT_ENERGY and PMT_EVENT_ACTIVITY are produced in fixed point
> format. File system code must output as floating point values.
> 
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
>  include/linux/resctrl_types.h           | 11 ++++++++
>  arch/x86/kernel/cpu/resctrl/intel_aet.c | 33 +++++++++++++++++++++++
>  fs/resctrl/monitor.c                    | 35 ++++++++++++++-----------
>  3 files changed, 64 insertions(+), 15 deletions(-)
> 
> diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
> index d98351663c2c..6838b02d5ca3 100644
> --- a/include/linux/resctrl_types.h
> +++ b/include/linux/resctrl_types.h
> @@ -47,6 +47,17 @@ enum resctrl_event_id {
>  	QOS_L3_MBM_TOTAL_EVENT_ID	= 0x02,
>  	QOS_L3_MBM_LOCAL_EVENT_ID	= 0x03,
>  
> +	/* Intel Telemetry Events */
> +	PMT_EVENT_ENERGY,
> +	PMT_EVENT_ACTIVITY,
> +	PMT_EVENT_STALLS_LLC_HIT,
> +	PMT_EVENT_C1_RES,
> +	PMT_EVENT_UNHALTED_CORE_CYCLES,
> +	PMT_EVENT_STALLS_LLC_MISS,
> +	PMT_EVENT_AUTO_C6_RES,
> +	PMT_EVENT_UNHALTED_REF_CYCLES,
> +	PMT_EVENT_UOPS_RETIRED,
> +
>  	/* Must be the last */
>  	QOS_NUM_EVENTS,
>  };
> diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> index c770039b2525..f9b2959693a0 100644
> --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
> +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> @@ -32,6 +32,20 @@ struct mmio_info {
>  	void __iomem	*addrs[] __counted_by(num_regions);
>  };
>  
> +/**
> + * struct pmt_event - Telemetry event.
> + * @id:		Resctrl event id.
> + * @idx:	Counter index within each per-RMID block of counters.
> + * @bin_bits:	Zero for integer valued events, else number bits in fixed-point.
> + */
> +struct pmt_event {
> +	enum resctrl_event_id	id;
> +	int			idx;
> +	int			bin_bits;

As I understand a negative value will be inappropriate for idx as well as bin_bits.
It looks like "unsigned int" is more appropriate?

> +};
> +
> +#define EVT(_id, _idx, _bits) { .id = _id, .idx = _idx, .bin_bits = _bits }
> +
>  /**
>   * struct event_group - All information about a group of telemetry events.
>   * @pfg:		Points to the aggregated telemetry space information
> @@ -40,6 +54,8 @@ struct mmio_info {
>   * @pkginfo:		Per-package MMIO addresses of telemetry regions belonging to this group.
>   * @guid:		Unique number per XML description file.
>   * @mmio_size:		Number of bytes of MMIO registers for this group.
> + * @num_events:		Number of events in this group.
> + * @evts:		Array of event descriptors.
>   */
>  struct event_group {
>  	/* Data fields for additional structures to manage this group. */
> @@ -49,6 +65,8 @@ struct event_group {
>  	/* Remaining fields initialized from XML file. */
>  	u32				guid;
>  	size_t				mmio_size;
> +	int				num_events;

unsigned int also seems more appropriate to reflect this is a value that
can never be negative. Also relevant to mmio_info::num_regions.

> +	struct pmt_event		evts[] __counted_by(num_events);
>  };
>  
>  #define XML_MMIO_SIZE(num_rmids, num_events, num_extra_status)	\

Reinette