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SubjectRe: [PATCH v8 1/3] perf x86: Infrastructure for exposing an Uncore unit to PMON mapping
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On 20.03.2020 10:31, roman.sudarikov@linux.intel.com wrote:
> From: Roman Sudarikov <roman.sudarikov@linux.intel.com>
>
> Intel® Xeon® Scalable processor family (code name Skylake-SP) makes
> significant changes in the integrated I/O (IIO) architecture. The new
> solution introduces IIO stacks which are responsible for managing traffic
> between the PCIe domain and the Mesh domain. Each IIO stack has its own
> PMON block and can handle either DMI port, x16 PCIe root port, MCP-Link
> or various built-in accelerators. IIO PMON blocks allow concurrent
> monitoring of I/O flows up to 4 x4 bifurcation within each IIO stack.
>
> Software is supposed to program required perf counters within each IIO
> stack and gather performance data. The tricky thing here is that IIO PMON
> reports data per IIO stack but users have no idea what IIO stacks are -
> they only know devices which are connected to the platform.
>
> Understanding IIO stack concept to find which IIO stack that particular
> IO device is connected to, or to identify an IIO PMON block to program
> for monitoring specific IIO stack assumes a lot of implicit knowledge
> about given Intel server platform architecture.
>
> Usage example:
> ls /sys/devices/uncore_<type>_<pmu_idx>/die*
>
> Each Uncore unit type, by its nature, can be mapped to its own context,
> for example:
> 1. CHA - each uncore_cha_<pmu_idx> is assigned to manage a distinct slice
> of LLC capacity;
> 2. UPI - each uncore_upi_<pmu_idx> is assigned to manage one link of Intel
> UPI Subsystem;
> 3. IIO - each uncore_iio_<pmu_idx> is assigned to manage one stack of the
> IIO module;
> 4. IMC - each uncore_imc_<pmu_idx> is assigned to manage one channel of
> Memory Controller.
>
> Implementation details:
> Optional callbacks added to struct intel_uncore_type to discover and map
> Uncore units to PMONs:
> int (*set_mapping)(struct intel_uncore_type *type)
> void (*cleanup_mapping)(struct intel_uncore_type *type)
>
> Details of IIO Uncore unit mapping to IIO PMON:
> Each IIO stack is either DMI port, x16 PCIe root port, MCP-Link or various
> built-in accelerators. For Uncore IIO Unit type, the mapping file
> holds bus numbers of devices, which can be monitored by that IIO PMON block
> on each die.
>
> Co-developed-by: Alexander Antonov <alexander.antonov@intel.com>
> Signed-off-by: Alexander Antonov <alexander.antonov@intel.com>
> Signed-off-by: Roman Sudarikov <roman.sudarikov@linux.intel.com>
> Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
> ---
> arch/x86/events/intel/uncore.c | 8 ++++++++
> arch/x86/events/intel/uncore.h | 6 ++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index 86467f85c383..fb693608c223 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -843,10 +843,12 @@ static int uncore_pmu_register(struct intel_uncore_pmu *pmu)
> .read = uncore_pmu_event_read,
> .module = THIS_MODULE,
> .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
> + .attr_update = pmu->type->attr_update,
> };
> } else {
> pmu->pmu = *pmu->type->pmu;
> pmu->pmu.attr_groups = pmu->type->attr_groups;
> + pmu->pmu.attr_update = pmu->type->attr_update;
> }
>
> if (pmu->type->num_boxes == 1) {
> @@ -887,6 +889,9 @@ static void uncore_type_exit(struct intel_uncore_type *type)
> struct intel_uncore_pmu *pmu = type->pmus;
> int i;
>
> + if (type->cleanup_mapping)
> + type->cleanup_mapping(type);
> +
> if (pmu) {
> for (i = 0; i < type->num_boxes; i++, pmu++) {
> uncore_pmu_unregister(pmu);
> @@ -954,6 +959,9 @@ static int __init uncore_type_init(struct intel_uncore_type *type, bool setid)
>
> type->pmu_group = &uncore_pmu_attr_group;
>
> + if (type->set_mapping)
> + type->set_mapping(type);
> +
> return 0;
>
> err:
> diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
> index bbfdaa720b45..d41f8874adc5 100644
> --- a/arch/x86/events/intel/uncore.h
> +++ b/arch/x86/events/intel/uncore.h
> @@ -72,7 +72,13 @@ struct intel_uncore_type {
> struct uncore_event_desc *event_descs;
> struct freerunning_counters *freerunning;
> const struct attribute_group *attr_groups[4];
> + const struct attribute_group **attr_update;
> struct pmu *pmu; /* for custom pmu ops */
> + /* PMON's topologies */
> + u64 *topology;
> + /* mapping Uncore units to PMON ranges */
> + int (*set_mapping)(struct intel_uncore_type *type);
> + void (*cleanup_mapping)(struct intel_uncore_type *type);
> };
>
> #define pmu_group attr_groups[0]
Hello Peter,
are you waiting for some further review/ack on this, or is it just in your
pending review queue?

Sorry for bothering you several times, but the feature will add value to
users.

Thanks,
Roman


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