[PATCH v3 0/2] perf stat: Fix uncore metric scaling across aggregation modes

[PATCH v3 0/2] perf stat: Fix uncore metric scaling across aggregation modes

[Chun-Tse Shao]

This series fixes a scaling issue for metrics (like lpm_miss_lat) across
different runtime aggregation modes.

Uncore metrics currently use `source_count` to scale events. However,
`source_count` returns the total uncore unit count regardless of the
selected aggregation mode. When evaluating metrics in different
aggregation mode other than `--per-socket`, this incorrectly divides
aggregated uncore events against the total uncore count rather than the
uncores belonging to the aggregation, leading to wrong metric results.

To fix this, we:
1. Introduce the aggr_nr() keyword to the metric parser, which
dynamically resolves to the active units in the current aggregation
group (`gr->nr`).

2. Update the python metrics to use `aggr_nr` instead of `source_count`,
ensuring correct scaling across all runtime aggregation boundaries.

Before the fix (incorrect low latency in global mode):
  $ perf stat -M lpm_miss_lat --metric-only -a -j -- sleep 1
  {"ns  lpm_miss_lat_rem" : "122.8", "ns  lpm_miss_lat_loc" : "114.5"}
  $ perf stat -M lpm_miss_lat --per-socket --metric-only -a -j -- sleep 1
  {"socket" : "S0", "ns  lpm_miss_lat_rem" : "232.1", "ns  lpm_miss_lat_loc" : "278.2"}
  {"socket" : "S1", "ns  lpm_miss_lat_rem" : "233.9", "ns  lpm_miss_lat_loc" : "257.5"}

After the fix (correct scaled latency in all aggregation modes):
  $ perf stat -M lpm_miss_lat --metric-only -a -j -- sleep 1
  {"ns  lpm_miss_lat_rem" : "231.7", "ns  lpm_miss_lat_loc" : "245.0"}
  $ perf stat -M lpm_miss_lat --per-socket --metric-only -a -j -- sleep 1
  {"socket" : "S0", "ns  lpm_miss_lat_rem" : "238.3", "ns  lpm_miss_lat_loc" : "249.4"}
  {"socket" : "S1", "ns  lpm_miss_lat_rem" : "259.1", "ns  lpm_miss_lat_loc" : "253.1"}

v3:
  Fixed based on Sashiko review:
  - Removed the unnecessary, copied `redefined-builtin` pylint-disable
    comment from `aggr_nr` definition inside `metric.py`.

v2: lore.kernel.org/20260521035941.3860145-1-ctshao@google.com
  Fixed based on Sashiko review:
  - Fixed `aggr_nr` setting when an uncore event fails to run
    (counts.run == 0) to explicitly set it to 0 instead of defaulting to
    1.
  - Accumulated `aggr_nr` when multiple unmerged PMU events are
    associated with the same metric ID to prevent incorrect scaling
    across active sockets.
  - Removed unused `List` import from `typing` in `intel_metrics.py`.

v1: lore.kernel.org/20260520180032.3045144-1-ctshao@google.com

Chun-Tse Shao (2):
  perf stat: Add aggr_nr metric parser support
  perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics

 tools/perf/pmu-events/intel_metrics.py |  6 +++---
 tools/perf/pmu-events/metric.py        |  9 +++++++--
 tools/perf/util/expr.c                 | 26 ++++++++++++++++++++++----
 tools/perf/util/expr.h                 |  6 +++++-
 tools/perf/util/expr.l                 |  1 +
 tools/perf/util/expr.y                 | 24 +++++++++++++++++-------
 tools/perf/util/stat-shadow.c          |  6 +++++-
 7 files changed, 60 insertions(+), 18 deletions(-)

--
2.54.0.746.g67dd491aae-goog

[PATCH v3 1/2] perf stat: Add aggr_nr metric parser support

[Chun-Tse Shao]

Introduce the `aggr_nr` function to the metric expression parser.
`aggr_nr` allows metric formulas to dynamically utilize the number of
aggregated targets (`aggr->nr`) instead of relying on the static
`source_count` (which represents the static socket or node count).

This adds the `AGGR_NR` token to the lexer and parser, updates the
expression parsing context helpers to store `aggr_nr`, and feeds
`aggr->nr` from the aggregation structure in `prepare_metric`.

Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Assisted-by: Gemini:gemini-3.1-pro-preview
---
 tools/perf/util/expr.c        | 26 ++++++++++++++++++++++----
 tools/perf/util/expr.h        |  6 +++++-
 tools/perf/util/expr.l        |  1 +
 tools/perf/util/expr.y        | 24 +++++++++++++++++-------
 tools/perf/util/stat-shadow.c |  6 +++++-
 5 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c
index 644769e92708..232998fef72b 100644
--- a/tools/perf/util/expr.c
+++ b/tools/perf/util/expr.c
@@ -27,6 +27,7 @@ struct expr_id_data {
 		struct {
 			double val;
 			int source_count;
+			int aggr_nr;
 		} val;
 		struct {
 			double val;
@@ -151,8 +152,8 @@ int expr__add_id_val(struct expr_parse_ctx *ctx, const char *id, double val)
 }

 /* Caller must make sure id is allocated */
-int expr__add_id_val_source_count(struct expr_parse_ctx *ctx, const char *id,
-				  double val, int source_count)
+int expr__add_id_val_source_count_aggr_nr(struct expr_parse_ctx *ctx, const char *id,
+					  double val, int source_count, int aggr_nr)
 {
 	struct expr_id_data *data_ptr = NULL, *old_data = NULL;
 	char *old_key = NULL;
@@ -163,6 +164,7 @@ int expr__add_id_val_source_count(struct expr_parse_ctx *ctx, const char *id,
 		return -ENOMEM;
 	data_ptr->val.val = val;
 	data_ptr->val.source_count = source_count;
+	data_ptr->val.aggr_nr = aggr_nr;
 	data_ptr->kind = EXPR_ID_DATA__VALUE;

 	ret = hashmap__set(ctx->ids, id, data_ptr, &old_key, &old_data);
@@ -171,12 +173,20 @@ int expr__add_id_val_source_count(struct expr_parse_ctx *ctx, const char *id,
 	} else if (old_data) {
 		data_ptr->val.val += old_data->val.val;
 		data_ptr->val.source_count += old_data->val.source_count;
+		data_ptr->val.aggr_nr += old_data->val.aggr_nr;
 	}
 	free(old_key);
 	free(old_data);
 	return ret;
 }

+/* Caller must make sure id is allocated */
+int expr__add_id_val_source_count(struct expr_parse_ctx *ctx, const char *id,
+				  double val, int source_count)
+{
+	return expr__add_id_val_source_count_aggr_nr(ctx, id, val, source_count, 1);
+}
+
 int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
 {
 	struct expr_id_data *data_ptr = NULL, *old_data = NULL;
@@ -390,8 +400,16 @@ double expr_id_data__value(const struct expr_id_data *data)

 double expr_id_data__source_count(const struct expr_id_data *data)
 {
-	assert(data->kind == EXPR_ID_DATA__VALUE);
-	return data->val.source_count;
+	if (data->kind == EXPR_ID_DATA__VALUE)
+		return data->val.source_count;
+	return 1.0;
+}
+
+double expr_id_data__aggr_nr(const struct expr_id_data *data)
+{
+	if (data->kind == EXPR_ID_DATA__VALUE)
+		return data->val.aggr_nr;
+	return 1.0;
 }

 double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx)
diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
index c0cec29ddc29..ed12e4007d2d 100644
--- a/tools/perf/util/expr.h
+++ b/tools/perf/util/expr.h
@@ -36,7 +36,9 @@ void expr__del_id(struct expr_parse_ctx *ctx, const char *id);
 int expr__add_id(struct expr_parse_ctx *ctx, const char *id);
 int expr__add_id_val(struct expr_parse_ctx *ctx, const char *id, double val);
 int expr__add_id_val_source_count(struct expr_parse_ctx *ctx, const char *id,
-				double val, int source_count);
+				  double val, int source_count);
+int expr__add_id_val_source_count_aggr_nr(struct expr_parse_ctx *ctx, const char *id,
+					  double val, int source_count, int aggr_nr);
 int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref);
 int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
 		 struct expr_id_data **data);
@@ -53,6 +55,8 @@ int expr__find_ids(const char *expr, const char *one,

 double expr_id_data__value(const struct expr_id_data *data);
 double expr_id_data__source_count(const struct expr_id_data *data);
+double expr_id_data__aggr_nr(const struct expr_id_data *data);
+
 double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx);
 double expr__has_event(const struct expr_parse_ctx *ctx, bool compute_ids, const char *id);
 double expr__strcmp_cpuid_str(const struct expr_parse_ctx *ctx, bool compute_ids, const char *id);
diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
index a2fc43159ee9..f16ccff278d0 100644
--- a/tools/perf/util/expr.l
+++ b/tools/perf/util/expr.l
@@ -121,6 +121,7 @@ min		{ return MIN; }
 if		{ return IF; }
 else		{ return ELSE; }
 source_count	{ return SOURCE_COUNT; }
+aggr_nr		{ return AGGR_NR; }
 has_event	{ return HAS_EVENT; }
 strcmp_cpuid_str	{ return STRCMP_CPUID_STR; }
 NaN		{ return nan_value(yyscanner); }
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index e364790babb5..e20f649354cf 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -41,7 +41,7 @@ int expr_lex(YYSTYPE * yylval_param , void *yyscanner);
 	} ids;
 }

-%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT HAS_EVENT STRCMP_CPUID_STR EXPR_ERROR
+%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT AGGR_NR HAS_EVENT STRCMP_CPUID_STR EXPR_ERROR
 %left MIN MAX IF
 %left '|'
 %left '^'
@@ -87,8 +87,14 @@ static struct ids union_expr(struct ids ids1, struct ids ids2)
 	return result;
 }

+enum expr_id_kind {
+	EXPR_ID_KIND__VALUE,
+	EXPR_ID_KIND__SOURCE_COUNT,
+	EXPR_ID_KIND__AGGR_NR,
+};
+
 static struct ids handle_id(struct expr_parse_ctx *ctx, char *id,
-			    bool compute_ids, bool source_count)
+			    bool compute_ids, enum expr_id_kind kind)
 {
 	struct ids result;

@@ -101,9 +107,12 @@ static struct ids handle_id(struct expr_parse_ctx *ctx, char *id,

 		result.val = NAN;
 		if (expr__resolve_id(ctx, id, &data) == 0) {
-			result.val = source_count
-				? expr_id_data__source_count(data)
-				: expr_id_data__value(data);
+			if (kind == EXPR_ID_KIND__SOURCE_COUNT)
+				result.val = expr_id_data__source_count(data);
+			else if (kind == EXPR_ID_KIND__AGGR_NR)
+				result.val = expr_id_data__aggr_nr(data);
+			else
+				result.val = expr_id_data__value(data);
 		}
 		result.ids = NULL;
 		free(id);
@@ -201,8 +210,9 @@ expr: NUMBER
 	$$.val = $1;
 	$$.ids = NULL;
 }
-| ID				{ $$ = handle_id(ctx, $1, compute_ids, /*source_count=*/false); }
-| SOURCE_COUNT '(' ID ')'	{ $$ = handle_id(ctx, $3, compute_ids, /*source_count=*/true); }
+| ID				{ $$ = handle_id(ctx, $1, compute_ids, EXPR_ID_KIND__VALUE); }
+| SOURCE_COUNT '(' ID ')'	{ $$ = handle_id(ctx, $3, compute_ids, EXPR_ID_KIND__SOURCE_COUNT); }
+| AGGR_NR '(' ID ')'		{ $$ = handle_id(ctx, $3, compute_ids, EXPR_ID_KIND__AGGR_NR); }
 | HAS_EVENT '(' ID ')'
 {
 	$$.val = expr__has_event(ctx, compute_ids, $3);
diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index bc2d44df7baf..c17373bb0e1e 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -53,6 +53,7 @@ static int prepare_metric(struct perf_stat_config *config,

 	for (i = 0; metric_events[i]; i++) {
 		int source_count = 0, tool_aggr_idx;
+		int aggr_nr = 1;
 		bool is_tool_time =
 			tool_pmu__is_time_event(config, metric_events[i], &tool_aggr_idx);
 		struct perf_stat_evsel *ps = metric_events[i]->stats;
@@ -89,6 +90,7 @@ static int prepare_metric(struct perf_stat_config *config,
 			 */
 			val = NAN;
 			source_count = 0;
+			aggr_nr = 0;
 		} else {
 			struct perf_stat_aggr *aggr =
 				&ps->aggr[is_tool_time ? tool_aggr_idx : aggr_idx];
@@ -96,6 +98,7 @@ static int prepare_metric(struct perf_stat_config *config,
 			if (aggr->counts.run == 0) {
 				val = NAN;
 				source_count = 0;
+				aggr_nr = 0;
 			} else {
 				val = aggr->counts.val;
 				if (is_tool_time) {
@@ -104,13 +107,14 @@ static int prepare_metric(struct perf_stat_config *config,
 				}
 				if (!source_count)
 					source_count = evsel__source_count(metric_events[i]);
+				aggr_nr = aggr->nr ?: 1;
 			}
 		}
 		n = strdup(evsel__metric_id(metric_events[i]));
 		if (!n)
 			return -ENOMEM;

-		expr__add_id_val_source_count(pctx, n, val, source_count);
+		expr__add_id_val_source_count_aggr_nr(pctx, n, val, source_count, aggr_nr);
 	}

 	for (int j = 0; metric_refs && metric_refs[j].metric_name; j++) {
--
2.54.0.746.g67dd491aae-goog

[PATCH v3 2/2] perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics

[Chun-Tse Shao]

Update `metric.py` to support the new `aggr_nr` keyword in the python
metric generator. Replace the usage of `source_count` with `aggr_nr` in
`IntelMissLat` inside `intel_metrics.py` so that uncore latency metrics
(like `lpm_miss_lat`) scale correctly on multi-socket and SNC systems when
aggregated globally.

Additionally, update the validation bypass logic in `CheckEveryEvent()`
inside `metric.py` to whitelist 'cha' and 'uncore' events. This
prevents validation failures when compiling metrics referencing these
PMU-specific uncore events.

Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Assisted-by: Gemini:gemini-3.1-pro-preview
---
 tools/perf/pmu-events/intel_metrics.py | 6 +++---
 tools/perf/pmu-events/metric.py        | 9 +++++++--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/tools/perf/pmu-events/intel_metrics.py b/tools/perf/pmu-events/intel_metrics.py
index 52035433b505..d99c7dd43797 100755
--- a/tools/perf/pmu-events/intel_metrics.py
+++ b/tools/perf/pmu-events/intel_metrics.py
@@ -7,7 +7,7 @@ import os
 import re
 from typing import Optional
 from common_metrics import Cycles
-from metric import (d_ratio, has_event, max, source_count, CheckPmu, Event,
+from metric import (d_ratio, has_event, max, aggr_nr, CheckPmu, Event,
                     JsonEncodeMetric, JsonEncodeMetricGroupDescriptions,
                     Literal, LoadEvents, Metric, MetricConstraint, MetricGroup,
                     MetricRef, Select)
@@ -674,10 +674,10 @@ def IntelMissLat() -> Optional[MetricGroup]:
     else:
         assert data_rd_loc_occ.name == "UNC_CHA_TOR_OCCUPANCY.IA_MISS_DRD_LOCAL", data_rd_loc_occ
 
-    ticks_per_cha = ticks / source_count(data_rd_loc_ins)
+    ticks_per_cha = ticks / aggr_nr(data_rd_loc_ins)
     loc_lat = interval_sec * 1e9 * data_rd_loc_occ / \
         (ticks_per_cha * data_rd_loc_ins)
-    ticks_per_cha = ticks / source_count(data_rd_rem_ins)
+    ticks_per_cha = ticks / aggr_nr(data_rd_rem_ins)
     rem_lat = interval_sec * 1e9 * data_rd_rem_occ / \
         (ticks_per_cha * data_rd_rem_ins)
     return MetricGroup("lpm_miss_lat", [
diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py
index ac582db785fc..a91ccb5977f0 100644
--- a/tools/perf/pmu-events/metric.py
+++ b/tools/perf/pmu-events/metric.py
@@ -93,7 +93,7 @@ def CheckEveryEvent(*names: str) -> None:
       name = name[:name.find(':')]
     elif '/' in name:
       name = name[:name.find('/')]
-      if any([name.startswith(x) for x in ['amd', 'arm', 'cpu', 'msr', 'power']]):
+      if any([name.startswith(x) for x in ['amd', 'arm', 'cpu', 'msr', 'power', 'cha', 'uncore']]):
         continue
     if name not in all_events_all_models:
       raise Exception(f"Is {name} a named json event?")
@@ -576,6 +576,11 @@ def source_count(event: Event) -> Function:
   return Function('source_count', event)
 
 
+def aggr_nr(event: Event) -> Function:
+  # pylint: disable=invalid-name
+  return Function('aggr_nr', event)
+
+
 def has_event(event: Event) -> Function:
   # pylint: disable=redefined-builtin
   # pylint: disable=invalid-name
@@ -762,7 +767,7 @@ def ParsePerfJson(orig: str) -> Expression:
   # Convert accidentally converted scientific notation constants back
   py = re.sub(r'([0-9]+)Event\(r"(e[0-9]*)"\)', r'\1\2', py)
   # Convert all the known keywords back from events to just the keyword
-  keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count', 'has_event', 'strcmp_cpuid_str']
+  keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count', 'aggr_nr', 'has_event', 'strcmp_cpuid_str']
   for kw in keywords:
     py = re.sub(rf'Event\(r"{kw}"\)', kw, py)
   try:
-- 
2.54.0.746.g67dd491aae-goog

Re: [PATCH v3 2/2] perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Replacing `source_count` with `aggr_nr` for uncore events yields mathematically incorrect metrics.
--

commit 25ed3f24e52414351780a2cc517f2d6534c79d03
Author: Chun-Tse Shao <ctshao@google.com>

perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics

Update metric.py to support the new aggr_nr keyword in the python metric
generator. Replace the usage of source_count with aggr_nr in IntelMissLat
inside intel_metrics.py so that uncore latency metrics scale correctly on
multi-socket and SNC systems when aggregated globally.

> diff --git a/tools/perf/pmu-events/intel_metrics.py b/tools/perf/pmu-events/intel_metrics.py
> index 52035433b5054..d99c7dd43797c 100755
> --- a/tools/perf/pmu-events/intel_metrics.py
> +++ b/tools/perf/pmu-events/intel_metrics.py
[ ... ]
> @@ -674,10 +674,10 @@ def IntelMissLat() -> Optional[MetricGroup]:
>      else:
>          assert data_rd_loc_occ.name == "UNC_CHA_TOR_OCCUPANCY.IA_MISS_DRD_LOCAL", data_rd_loc_occ
>  
> -    ticks_per_cha = ticks / source_count(data_rd_loc_ins)
> +    ticks_per_cha = ticks / aggr_nr(data_rd_loc_ins)

[Severity: Medium]
Does replacing source_count with aggr_nr here yield a mathematically incorrect
metric?

aggr_nr evaluates to the number of CPUs in the aggregation unit for a specific
evsel, while source_count correctly tracks the number of PMU event sources
(e.g., total CHAs).

For system-wide uncore events in global aggregation mode (AGGR_GLOBAL), each
PMU's evsel typically monitors a single CPU mask, so its aggr->nr evaluates
to 1.

Could dividing ticks by 1 instead of the total number of CHAs result in
metrics being off by a factor of the system's CHA count?

>      loc_lat = interval_sec * 1e9 * data_rd_loc_occ / \
>          (ticks_per_cha * data_rd_loc_ins)
> -    ticks_per_cha = ticks / source_count(data_rd_rem_ins)
> +    ticks_per_cha = ticks / aggr_nr(data_rd_rem_ins)
>      rem_lat = interval_sec * 1e9 * data_rd_rem_occ / \
>          (ticks_per_cha * data_rd_rem_ins)
>      return MetricGroup("lpm_miss_lat", [

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260521201505.124690-1-ctshao@google.com?part=2

Re: [PATCH v3 2/2] perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics

[Chun-Tse Shao]

On Thu, May 21, 2026 at 2:08 PM <sashiko-bot@kernel.org> wrote:
>
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Replacing `source_count` with `aggr_nr` for uncore events yields mathematically incorrect metrics.
> --
>
> commit 25ed3f24e52414351780a2cc517f2d6534c79d03
> Author: Chun-Tse Shao <ctshao@google.com>
>
> perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics
>
> Update metric.py to support the new aggr_nr keyword in the python metric
> generator. Replace the usage of source_count with aggr_nr in IntelMissLat
> inside intel_metrics.py so that uncore latency metrics scale correctly on
> multi-socket and SNC systems when aggregated globally.
>
> > diff --git a/tools/perf/pmu-events/intel_metrics.py b/tools/perf/pmu-events/intel_metrics.py
> > index 52035433b5054..d99c7dd43797c 100755
> > --- a/tools/perf/pmu-events/intel_metrics.py
> > +++ b/tools/perf/pmu-events/intel_metrics.py
> [ ... ]
> > @@ -674,10 +674,10 @@ def IntelMissLat() -> Optional[MetricGroup]:
> >      else:
> >          assert data_rd_loc_occ.name == "UNC_CHA_TOR_OCCUPANCY.IA_MISS_DRD_LOCAL", data_rd_loc_occ
> >
> > -    ticks_per_cha = ticks / source_count(data_rd_loc_ins)
> > +    ticks_per_cha = ticks / aggr_nr(data_rd_loc_ins)
>
> [Severity: Medium]
> Does replacing source_count with aggr_nr here yield a mathematically incorrect
> metric?
>
> aggr_nr evaluates to the number of CPUs in the aggregation unit for a specific
> evsel, while source_count correctly tracks the number of PMU event sources
> (e.g., total CHAs).
>
> For system-wide uncore events in global aggregation mode (AGGR_GLOBAL), each
> PMU's evsel typically monitors a single CPU mask, so its aggr->nr evaluates
> to 1.
>
> Could dividing ticks by 1 instead of the total number of CHAs result in
> metrics being off by a factor of the system's CHA count?
>

A false alarm, source_count is always a static number of evsel, which
should be replaced by aggr_nr when calculating per-socket metrics.


> >      loc_lat = interval_sec * 1e9 * data_rd_loc_occ / \
> >          (ticks_per_cha * data_rd_loc_ins)
> > -    ticks_per_cha = ticks / source_count(data_rd_rem_ins)
> > +    ticks_per_cha = ticks / aggr_nr(data_rd_rem_ins)
> >      rem_lat = interval_sec * 1e9 * data_rd_rem_occ / \
> >          (ticks_per_cha * data_rd_rem_ins)
> >      return MetricGroup("lpm_miss_lat", [
>
> --
> Sashiko AI review · https://sashiko.dev/#/patchset/20260521201505.124690-1-ctshao@google.com?part=2

Re: [PATCH v3 0/2] perf stat: Fix uncore metric scaling across aggregation modes

[Chen, Zide]

On 5/21/2026 3:15 PM, Chun-Tse Shao wrote:
> This series fixes a scaling issue for metrics (like lpm_miss_lat) across
> different runtime aggregation modes.
> 
> Uncore metrics currently use `source_count` to scale events. However,
> `source_count` returns the total uncore unit count regardless of the
> selected aggregation mode. When evaluating metrics in different
> aggregation mode other than `--per-socket`, this incorrectly divides
> aggregated uncore events against the total uncore count rather than the
> uncores belonging to the aggregation, leading to wrong metric results.
> 
> To fix this, we:
> 1. Introduce the aggr_nr() keyword to the metric parser, which
> dynamically resolves to the active units in the current aggregation
> group (`gr->nr`).
> 
> 2. Update the python metrics to use `aggr_nr` instead of `source_count`,
> ensuring correct scaling across all runtime aggregation boundaries.
> 
> Before the fix (incorrect low latency in global mode):
>   $ perf stat -M lpm_miss_lat --metric-only -a -j -- sleep 1
>   {"ns  lpm_miss_lat_rem" : "122.8", "ns  lpm_miss_lat_loc" : "114.5"}
>   $ perf stat -M lpm_miss_lat --per-socket --metric-only -a -j -- sleep 1
>   {"socket" : "S0", "ns  lpm_miss_lat_rem" : "232.1", "ns  lpm_miss_lat_loc" : "278.2"}
>   {"socket" : "S1", "ns  lpm_miss_lat_rem" : "233.9", "ns  lpm_miss_lat_loc" : "257.5"}
> 
> After the fix (correct scaled latency in all aggregation modes):
>   $ perf stat -M lpm_miss_lat --metric-only -a -j -- sleep 1
>   {"ns  lpm_miss_lat_rem" : "231.7", "ns  lpm_miss_lat_loc" : "245.0"}
>   $ perf stat -M lpm_miss_lat --per-socket --metric-only -a -j -- sleep 1
>   {"socket" : "S0", "ns  lpm_miss_lat_rem" : "238.3", "ns  lpm_miss_lat_loc" : "249.4"}
>   {"socket" : "S1", "ns  lpm_miss_lat_rem" : "259.1", "ns  lpm_miss_lat_loc" : "253.1"}
> 
> v3:
>   Fixed based on Sashiko review:
>   - Removed the unnecessary, copied `redefined-builtin` pylint-disable
>     comment from `aggr_nr` definition inside `metric.py`.
> 
> v2: lore.kernel.org/20260521035941.3860145-1-ctshao@google.com
>   Fixed based on Sashiko review:
>   - Fixed `aggr_nr` setting when an uncore event fails to run
>     (counts.run == 0) to explicitly set it to 0 instead of defaulting to
>     1.
>   - Accumulated `aggr_nr` when multiple unmerged PMU events are
>     associated with the same metric ID to prevent incorrect scaling
>     across active sockets.
>   - Removed unused `List` import from `typing` in `intel_metrics.py`.
> 
> v1: lore.kernel.org/20260520180032.3045144-1-ctshao@google.com
> 
> Chun-Tse Shao (2):
>   perf stat: Add aggr_nr metric parser support
>   perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics
> 
>  tools/perf/pmu-events/intel_metrics.py |  6 +++---
>  tools/perf/pmu-events/metric.py        |  9 +++++++--
>  tools/perf/util/expr.c                 | 26 ++++++++++++++++++++++----
>  tools/perf/util/expr.h                 |  6 +++++-
>  tools/perf/util/expr.l                 |  1 +
>  tools/perf/util/expr.y                 | 24 +++++++++++++++++-------
>  tools/perf/util/stat-shadow.c          |  6 +++++-
>  7 files changed, 60 insertions(+), 18 deletions(-)
> 
> --
> 2.54.0.746.g67dd491aae-goog

Tested the series on Intel CPUs.

Tested-by: Zide Chen <zide.chen@intel.com>

Re: [PATCH v3 0/2] perf stat: Fix uncore metric scaling across aggregation modes

[Namhyung Kim]

On Thu, May 21, 2026 at 01:15:03PM -0700, Chun-Tse Shao wrote:
> This series fixes a scaling issue for metrics (like lpm_miss_lat) across
> different runtime aggregation modes.
> 
> Uncore metrics currently use `source_count` to scale events. However,
> `source_count` returns the total uncore unit count regardless of the
> selected aggregation mode. When evaluating metrics in different
> aggregation mode other than `--per-socket`, this incorrectly divides
> aggregated uncore events against the total uncore count rather than the
> uncores belonging to the aggregation, leading to wrong metric results.
> 
> To fix this, we:
> 1. Introduce the aggr_nr() keyword to the metric parser, which
> dynamically resolves to the active units in the current aggregation
> group (`gr->nr`).
> 
> 2. Update the python metrics to use `aggr_nr` instead of `source_count`,
> ensuring correct scaling across all runtime aggregation boundaries.
> 
> Before the fix (incorrect low latency in global mode):
>   $ perf stat -M lpm_miss_lat --metric-only -a -j -- sleep 1
>   {"ns  lpm_miss_lat_rem" : "122.8", "ns  lpm_miss_lat_loc" : "114.5"}
>   $ perf stat -M lpm_miss_lat --per-socket --metric-only -a -j -- sleep 1
>   {"socket" : "S0", "ns  lpm_miss_lat_rem" : "232.1", "ns  lpm_miss_lat_loc" : "278.2"}
>   {"socket" : "S1", "ns  lpm_miss_lat_rem" : "233.9", "ns  lpm_miss_lat_loc" : "257.5"}
> 
> After the fix (correct scaled latency in all aggregation modes):
>   $ perf stat -M lpm_miss_lat --metric-only -a -j -- sleep 1
>   {"ns  lpm_miss_lat_rem" : "231.7", "ns  lpm_miss_lat_loc" : "245.0"}
>   $ perf stat -M lpm_miss_lat --per-socket --metric-only -a -j -- sleep 1
>   {"socket" : "S0", "ns  lpm_miss_lat_rem" : "238.3", "ns  lpm_miss_lat_loc" : "249.4"}
>   {"socket" : "S1", "ns  lpm_miss_lat_rem" : "259.1", "ns  lpm_miss_lat_loc" : "253.1"}
> 
> v3:
>   Fixed based on Sashiko review:
>   - Removed the unnecessary, copied `redefined-builtin` pylint-disable
>     comment from `aggr_nr` definition inside `metric.py`.
> 
> v2: lore.kernel.org/20260521035941.3860145-1-ctshao@google.com
>   Fixed based on Sashiko review:
>   - Fixed `aggr_nr` setting when an uncore event fails to run
>     (counts.run == 0) to explicitly set it to 0 instead of defaulting to
>     1.
>   - Accumulated `aggr_nr` when multiple unmerged PMU events are
>     associated with the same metric ID to prevent incorrect scaling
>     across active sockets.
>   - Removed unused `List` import from `typing` in `intel_metrics.py`.
> 
> v1: lore.kernel.org/20260520180032.3045144-1-ctshao@google.com
> 
> Chun-Tse Shao (2):
>   perf stat: Add aggr_nr metric parser support
>   perf stat: Use aggr_nr scaling for Intel uncore miss latency metrics

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung

> 
>  tools/perf/pmu-events/intel_metrics.py |  6 +++---
>  tools/perf/pmu-events/metric.py        |  9 +++++++--
>  tools/perf/util/expr.c                 | 26 ++++++++++++++++++++++----
>  tools/perf/util/expr.h                 |  6 +++++-
>  tools/perf/util/expr.l                 |  1 +
>  tools/perf/util/expr.y                 | 24 +++++++++++++++++-------
>  tools/perf/util/stat-shadow.c          |  6 +++++-
>  7 files changed, 60 insertions(+), 18 deletions(-)
> 
> --
> 2.54.0.746.g67dd491aae-goog
>