describe JVM CPU metrics (#13)

Co-authored-by: Josh Suereth <[email protected]>

CHANGELOG.md

@@ -59,3 +59,5 @@ release.
   ([#3355](https://github.com/open-telemetry/opentelemetry-specification/pull/3355))
 - Add `gcp.cloud_run.job.execution` and `gcp.cloud_run.job.task_id` resource
   attributes for GCP Cloud Run Jobs ([#3378](https://github.com/open-telemetry/opentelemetry-specification/pull/3378))
+- Specify the value range for JVM CPU metrics.
+  ([#13](https://github.com/open-telemetry/semantic-conventions/pull/13))

semantic_conventions/metrics/process-runtime-jvm-metrics.yaml

@@ -127,8 +127,10 @@ groups:
     metric_name: process.runtime.jvm.cpu.utilization
     brief: "Recent CPU utilization for the process."
     note: >
+      The value range is [0.0,1.0].
       This utilization is not defined as being for the specific interval since last measurement
       (unlike `system.cpu.utilization`).
+      [Reference](https://docs.oracle.com/en/java/javase/17/docs/api/jdk.management/com/sun/management/OperatingSystemMXBean.html#getProcessCpuLoad()).
     instrument: gauge
     unit: "1"
 
@@ -137,15 +139,22 @@ groups:
     metric_name: process.runtime.jvm.system.cpu.utilization
     brief: "Recent CPU utilization for the whole system."
     note: >
+      The value range is [0.0,1.0].
       This utilization is not defined as being for the specific interval since last measurement
       (unlike `system.cpu.utilization`).
+      [Reference](https://docs.oracle.com/en/java/javase/17/docs/api/jdk.management/com/sun/management/OperatingSystemMXBean.html#getCpuLoad()).
     instrument: gauge
     unit: "1"
 
   - id: metric.process.runtime.jvm.system.cpu.load_1m
     type: metric
     metric_name: process.runtime.jvm.system.cpu.load_1m
     brief: "Average CPU load of the whole system for the last minute."
+    note: >
+      The value range is [0,n], where n is the number of CPU cores - or a negative number of the value is not available.
+      This utilization is not defined as being for the specific interval since last measurement
+      (unlike `system.cpu.utilization`).
+      [Reference](https://docs.oracle.com/en/java/javase/17/docs/api/java.management/java/lang/management/OperatingSystemMXBean.html#getSystemLoadAverage()).
     instrument: gauge
     unit: "1"