Clarify art.gc.gc-count-rate-histogram runtime stat.
(cherry pick commit 2d6327d0adaf6ca3d13e1e082f55680cfefcc449)
Bug: 21491908
Change-Id: I84d93aa73eebc327513c4663a6b606e2dad9a0b7
diff --git a/core/java/android/os/Debug.java b/core/java/android/os/Debug.java
index 2a60b4d..a435267 100644
--- a/core/java/android/os/Debug.java
+++ b/core/java/android/os/Debug.java
@@ -1090,13 +1090,30 @@
* </tr>
* <tr>
* <td>art.gc.gc-count-rate-histogram</td>
- * <td>The histogram of the number of garbage collection runs per 10 seconds.</td>
+ * <td>Every 10 seconds, the gc-count-rate is computed as the number of garbage
+ * collection runs that have occurred over the last 10
+ * seconds. art.gc.gc-count-rate-histogram is a histogram of the gc-count-rate
+ * samples taken since the process began. The histogram can be used to identify
+ * instances of high rates of garbage collection runs. For example, a histogram
+ * of "0:34503,1:45350,2:11281,3:8088,4:43,5:8" shows that most of the time
+ * there are between 0 and 2 garbage collection runs every 10 seconds, but there
+ * were 8 distinct 10-second intervals in which 5 garbage collection runs
+ * occurred.</td>
* <td>{@code 0:34503,1:45350,2:11281,3:8088,4:43,5:8}</td>
* <td>23</td>
* </tr>
* <tr>
* <td>art.gc.blocking-gc-count-rate-histogram</td>
- * <td>The histogram of the number of garbage collection runs per 10 seconds.</td>
+ * <td>Every 10 seconds, the blocking-gc-count-rate is computed as the number of
+ * blocking garbage collection runs that have occurred over the last 10
+ * seconds. art.gc.blocking-gc-count-rate-histogram is a histogram of the
+ * blocking-gc-count-rate samples taken since the process began. The histogram
+ * can be used to identify instances of high rates of blocking garbage
+ * collection runs. For example, a histogram of "0:99269,1:1,2:1" shows that
+ * most of the time there are zero blocking garbage collection runs every 10
+ * seconds, but there was one 10-second interval in which one blocking garbage
+ * collection run occurred, and there was one interval in which two blocking
+ * garbage collection runs occurred.</td>
* <td>{@code 0:99269,1:1,2:1}</td>
* <td>23</td>
* </tr>
