Bug 1795047 - Power use feature string should clarify what's available on each platform, r=canaltinova,dlrobertson.

Differential Revision: https://phabricator.services.mozilla.com/D159685

devtools/client/performance-new/utils.js

@@ -11,6 +11,10 @@
 
 const UNITS = ["B", "kiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"];
 
+const AppConstants = ChromeUtils.importESModule(
+  "resource://gre/modules/AppConstants.sys.mjs"
+).AppConstants;
+
 /**
  * Linearly interpolate between values.
  * https://en.wikipedia.org/wiki/Linear_interpolation
@@ -533,9 +537,24 @@ const featureDescriptions = [
   {
     name: "Power Use",
     value: "power",
-    title:
+    title: (() => {
-      "Record the value of every energy meter available on the system with " +
+      switch (AppConstants.platform) {
-      "each sample. Only available on Windows 11 and Apple Silicon.",
+        case "win":
+          return (
+            "Record the value of every energy meter available on the system with " +
+            "each sample. Only available on Windows 11 with Intel CPUs."
+          );
+        case "linux":
+          return (
+            "Record the power used by the entire system with each sample. " +
+            "Only available with Intel CPUs and requires setting the sysctl kernel.perf_event_paranoid to 0."
+          );
+        case "macosx":
+          return "Record the power used by the entire system (Intel) or each process (Apple Silicon) with each sample.";
+        default:
+          return "Not supported on this platform.";
+      }
+    })(),
     experimental: true,
   },
 ];

mozglue/baseprofiler/public/BaseProfilerState.h

@@ -143,6 +143,24 @@ class MOZ_RAII AutoProfilerStats {
 // Profiler features
 //---------------------------------------------------------------------------
 
+#  if defined(__APPLE__) && defined(__aarch64__)
+#    define POWER_HELP "Sample per process power use"
+#  elif defined(__APPLE__) && defined(__x86_64__)
+#    define POWER_HELP \
+      "Record the power used by the entire system with each sample."
+#  elif defined(__linux__) && defined(__x86_64__)
+#    define POWER_HELP                                                \
+      "Record the power used by the entire system with each sample. " \
+      "Only available with Intel CPUs and requires setting "          \
+      "the sysctl kernel.perf_event_paranoid to 0."
+#  elif defined(_MSC_VER)
+#    define POWER_HELP                                                       \
+      "Record the value of every energy meter available on the system with " \
+      "each sample. Only available on Windows 11 with Intel CPUs."
+#  else
+#    define POWER_HELP "Not supported on this platform."
+#  endif
+
 // Higher-order macro containing all the feature info in one place. Define
 // |MACRO| appropriately to extract the relevant parts. Note that the number
 // values are used internally only and so can be changed without consequence.
@@ -216,9 +234,7 @@ class MOZ_RAII AutoProfilerStats {
     MACRO(21, "processcpu", ProcessCPU,                                      \
           "Sample the CPU utilization of each process")                      \
                                                                              \
-    MACRO(22, "power", Power,                                                \
+    MACRO(22, "power", Power, POWER_HELP)
-          "Sample energy meters on Windows 11 and per process power use on " \
-          "Apple Silicon")
 // *** Synchronize with lists in ProfilerState.h and geckoProfiler.json ***
 
 struct ProfilerFeature {

tools/profiler/public/ProfilerState.h

@@ -22,6 +22,25 @@
 // Profiler features
 //---------------------------------------------------------------------------
 
+#if defined(__APPLE__) && defined(__aarch64__)
+#  define POWER_HELP "Sample per process power use"
+#elif defined(__APPLE__) && defined(__x86_64__)
+#  define POWER_HELP \
+    "Record the power used by the entire system with each sample."
+#elif defined(__linux__) && defined(__x86_64__)
+#  define POWER_HELP                                                \
+    "Record the power used by the entire system with each sample. " \
+    "Only available with Intel CPUs and requires setting "          \
+    "the sysctl kernel.perf_event_paranoid to 0."
+
+#elif defined(_MSC_VER)
+#  define POWER_HELP                                                       \
+    "Record the value of every energy meter available on the system with " \
+    "each sample. Only available on Windows 11 with Intel CPUs."
+#else
+#  define POWER_HELP "Not supported on this platform."
+#endif
+
 // Higher-order macro containing all the feature info in one place. Define
 // |MACRO| appropriately to extract the relevant parts. Note that the number
 // values are used internally only and so can be changed without consequence.
@@ -95,9 +114,7 @@
   MACRO(21, "processcpu", ProcessCPU,                                      \
         "Sample the CPU utilization of each process")                      \
                                                                            \
-  MACRO(22, "power", Power,                                                \
+  MACRO(22, "power", Power, POWER_HELP)
-        "Sample energy meters on Windows 11 and per process power use on " \
-        "Apple Silicon")
 // *** Synchronize with lists in BaseProfilerState.h and geckoProfiler.json ***
 
 struct ProfilerFeature {