From: Ian Rogers <irogers@google.com>
Date: Tue, 27 Jan 2026 18:44:55 +0000 (-0800)
Subject: perf jevents: Add context switch metrics for Intel
X-Git-Tag: v7.0-rc1~16^2~67
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2f3d6ea05deca7c1c653e2e53d73ac5a81378d53;p=thirdparty%2Flinux.git

perf jevents: Add context switch metrics for Intel

Metrics break down context switches for different kinds of
instruction.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Thomas Falcon <thomas.falcon@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Benjamin Gray <bgray@linux.ibm.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Edward Baker <edward.baker@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Xu Yang <xu.yang_2@nxp.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/pmu-events/intel_metrics.py b/tools/perf/pmu-events/intel_metrics.py
index bc3c50285916..9cf4bd8ac769 100755
--- a/tools/perf/pmu-events/intel_metrics.py
+++ b/tools/perf/pmu-events/intel_metrics.py
@@ -263,6 +263,63 @@ def IntelBr():
                        description="breakdown of retired branch instructions")
 
 
+def IntelCtxSw() -> MetricGroup:
+    cs = Event("context\\-switches")
+    metrics = [
+        Metric("lpm_cs_rate", "Context switches per second",
+               d_ratio(cs, interval_sec), "ctxsw/s")
+    ]
+
+    ev = Event("instructions")
+    metrics.append(Metric("lpm_cs_instr", "Instructions per context switch",
+                          d_ratio(ev, cs), "instr/cs"))
+
+    ev = Event("cycles")
+    metrics.append(Metric("lpm_cs_cycles", "Cycles per context switch",
+                          d_ratio(ev, cs), "cycles/cs"))
+
+    try:
+        ev = Event("MEM_INST_RETIRED.ALL_LOADS", "MEM_UOPS_RETIRED.ALL_LOADS")
+        metrics.append(Metric("lpm_cs_loads", "Loads per context switch",
+                              d_ratio(ev, cs), "loads/cs"))
+    except:
+        pass
+
+    try:
+        ev = Event("MEM_INST_RETIRED.ALL_STORES",
+                   "MEM_UOPS_RETIRED.ALL_STORES")
+        metrics.append(Metric("lpm_cs_stores", "Stores per context switch",
+                              d_ratio(ev, cs), "stores/cs"))
+    except:
+        pass
+
+    try:
+        ev = Event("BR_INST_RETIRED.NEAR_TAKEN", "BR_INST_RETIRED.TAKEN_JCC")
+        metrics.append(Metric("lpm_cs_br_taken", "Branches taken per context switch",
+                              d_ratio(ev, cs), "br_taken/cs"))
+    except:
+        pass
+
+    try:
+        l2_misses = (Event("L2_RQSTS.DEMAND_DATA_RD_MISS") +
+                     Event("L2_RQSTS.RFO_MISS") +
+                     Event("L2_RQSTS.CODE_RD_MISS"))
+        try:
+            l2_misses += Event("L2_RQSTS.HWPF_MISS",
+                               "L2_RQSTS.L2_PF_MISS", "L2_RQSTS.PF_MISS")
+        except:
+            pass
+
+        metrics.append(Metric("lpm_cs_l2_misses", "L2 misses per context switch",
+                              d_ratio(l2_misses, cs), "l2_misses/cs"))
+    except:
+        pass
+
+    return MetricGroup("lpm_cs", metrics,
+                       description=("Number of context switches per second, instructions "
+                                    "retired & core cycles between context switches"))
+
+
 def IntelIlp() -> MetricGroup:
     tsc = Event("msr/tsc/")
     c0 = Event("msr/mperf/")
@@ -678,6 +735,7 @@ def main() -> None:
         Smi(),
         Tsx(),
         IntelBr(),
+        IntelCtxSw(),
         IntelIlp(),
         IntelL2(),
         IntelLdSt(),