Adding CPU and I/O metrics to process module

docs/api/process.md

@@ -116,3 +116,15 @@ Returns `Object`:
 
 Returns an object giving memory usage statistics about the entire system. Note
 that all statistics are reported in Kilobytes.
+
+### `process.getCPUUsage()`
+
+Returns:
+
+* `CPUUsage` [CPUUsage](structures/cpu-usage.md)
+
+### `process.getIOCounters()`
+
+Returns:
+
+* `IOCounters` [IOCounters](structures/io-counters.md)

docs/api/structures/cpu-usage.md

@@ -0,0 +1,6 @@
+# CPUUsage Object
+
+* `percentCPUUsage` number - Percentage of CPU used since the last call to getCPUUsage.
+  First call returns 0.
+* `idleWakeupsPerSecond` number - The number of average idle cpu wakeups per second
+  since the last call to getCPUUsage. First call returns 0.

docs/api/structures/io-counters.md

@@ -0,0 +1,8 @@
+# IOCounters Object
+
+* `readOperationCount` Number - The number of I/O read operations.
+* `writeOperationCount` Number - The number of I/O write operations.
+* `otherOperationCount` Number - Then number of I/O other operations.
+* `readTransferCount` Number - The number of I/O read transfers.
+* `writeTransferCount` Number - The number of I/O write transfers.
+* `otherTransferCount` Number - Then number of I/O other transfers.