Messages in this thread |  | | Date | Tue, 9 Dec 2025 11:41:10 -0800 | | Subject | Re: [PATCH v15 16/32] x86/resctrl: Discover hardware telemetry events | | From | Reinette Chatre <> |
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Hi Tony,
On 12/4/25 12:53 PM, Tony Luck wrote: > Each CPU collects data for telemetry events that it sends to the nearest > telemetry event aggregator either when the value of MSR_IA32_PQR_ASSOC.RMID > changes, or when a two millisecond timer expires. > > There is a feature type ("energy" or "perf"), guid, and MMIO region associated > with each aggregator. This combination links to an XML description of the > set of telemetry events tracked by the aggregator. XML files are published > by Intel in a GitHub repository [1]. > > The telemetry event aggregators maintain per-RMID per-event counts of the > total seen for all the CPUs. There may be multiple telemetry event aggregators > per package. > > There are separate sets of aggregators for each feature type. Aggregators > in a set may have different guids. All aggregators with the same feature > type and guid are symmetric keeping counts for the same set of events for > the CPUs that provide data to them. > > The XML file for each aggregator provides the following information: > 0) Feature type of the events ("perf" or "energy") > 1) Which telemetry events are tracked by the aggregator. > 2) The order in which the event counters appear for each RMID. > 3) The value type of each event counter (integer or fixed-point). > 4) The number of RMIDs supported. > 5) Which additional aggregator status registers are included. > 6) The total size of the MMIO region for an aggregator. > > Introduce struct event_group that condenses the relevant information from > an XML file. Hereafter an "event group" refers to a group of events of a > particular feature type ("energy" or "perf") with a particular guid. > > The event_group::pfname field is used to choose the parameter to pass
Needs imperative and "field" is redundant.
Previous paragraph can introduce event_group::pfname, for example: Hereafter an "event group" refers to a group of events of a particular feature type (event_group::pfname set to "energy" or "perf") with a particular guid.
Then "Use event_group::pfname to determine the feature id needed to obtain the aggregator details. It will later ..."
> to intel_pmt_get_regions_by_feature(). It will later be used in console > messages and with the rdt= boot parameter. > > The INTEL_PMT_TELEMETRY driver enumerates support for telemetry events. > This driver provides intel_pmt_get_regions_by_feature() to list all available > telemetry event aggregators of a given feature type. The list includes the > "guid", the base address in MMIO space for the region where the event counters > are exposed, and the package id where the all the CPUs that report to this > aggregator are located. > > Call INTEL_PMT_TELEMETRY's intel_pmt_get_regions_by_feature() for each event > group to obtain a private copy of that event group's aggregator data. Duplicate > the aggregator data between event groups that have the same feature type > but different guid. Further processing on this private copy will be unique > to the event group. > > Return the aggregator data to INTEL_PMT_TELEMETRY at resctrl exit time. > > resctrl will silently ignore unknown guid values. > > Add a new Kconfig option CONFIG_X86_CPU_RESCTRL_INTEL_AET for the Intel specific > parts of telemetry code. This depends on the INTEL_PMT_TELEMETRY and INTEL_TPMI > drivers being built-in to the kernel for enumeration of telemetry features. > > Signed-off-by: Tony Luck <tony.luck@intel.com> > Link: https://github.com/intel/Intel-PMT # [1] > ---
...
> +/** > + * struct event_group - Events with the same feature type ("energy" or "perf") and guid. > + * @pfname: PMT feature name (energy or perf) of this event group > + * used by boot rdt= option.
nit: use quotes for energy and perf as in previous line to be consistent and help to highlight that these are string values.
nit: move "used by boot rdt= option" to patch that introduces that usage.
> + * @pfg: Points to the aggregated telemetry space information > + * returned by the intel_pmt_get_regions_by_feature() > + * call to the INTEL_PMT_TELEMETRY driver that contains > + * data for all telemetry regions of type @pfname. > + * Valid if the system supports the event group, > + * NULL otherwise. > + */ > +struct event_group { > + /* Data fields for additional structures to manage this group. */ > + const char *pfname; > + struct pmt_feature_group *pfg; > +}; > +
| Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reinette
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