doc: update eventLoopUtilization documentation

PR-URL: #35155
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Rich Trott <[email protected]>

Author: addaleax

doc/api/perf_hooks.md

@@ -53,13 +53,13 @@ added: v8.5.0
 If `name` is not provided, removes all `PerformanceMark` objects from the
 Performance Timeline. If `name` is provided, removes only the named mark.
 
-### `performance.eventLoopUtilization([util1][,util2])`
+### `performance.eventLoopUtilization([utilization1[, utilization2]])`
 <!-- YAML
 added: v14.10.0
 -->
 
-* `util1` {Object} The result of a previous call to `eventLoopUtilization()`
-* `util2` {Object} The result of a previous call to `eventLoopUtilization()`
+* `utilization1` {Object} The result of a previous call to `eventLoopUtilization()`
+* `utilization2` {Object} The result of a previous call to `eventLoopUtilization()`
     prior to `util1`
 * Returns {Object}
   * `idle` {number}
@@ -72,23 +72,23 @@ high resolution milliseconds timer. The `utilization` value is the calculated
 Event Loop Utilization (ELU). If bootstrapping has not yet finished, the
 properties have the value of 0.
 
-`util1` and `util2` are optional parameters.
+`utilization1` and `utilization2` are optional parameters.
 
-If `util1` is passed then the delta between the current call's `active` and
-`idle` times are calculated and returned (similar to [`process.hrtime()`][]).
-Likewise the adjusted `utilization` value is calculated.
+If `utilization1` is passed, then the delta between the current call's `active`
+and `idle` times, as well as the corresponding `utilization` value are
+calculated and returned (similar to [`process.hrtime()`][]).
 
-If `util1` and `util2` are both passed then the calculation adjustments are
-done between the two arguments. This is a convenience option because unlike
-[`process.hrtime()`][] additional work is done to calculate the ELU.
+If `utilization1` and `utilization2` are both passed, then the delta is
+calculated between the two arguments. This is a convenience option because,
+unlike [`process.hrtime()`][], calculating the ELU is more complex than a
+single subtraction.
 
-ELU is similar to CPU utilization except that it is calculated using high
-precision wall-clock time. It represents the percentage of time the event loop
-has spent outside the event loop's event provider (e.g. `epoll_wait`). No other
-CPU idle time is taken into consideration. The following is an example of how
-a mostly idle process will have a high ELU.
+ELU is similar to CPU utilization, except that it only measures event loop
+statistics and not CPU usage. It represents the percentage of time the event
+loop has spent outside the event loop's event provider (e.g. `epoll_wait`).
+No other CPU idle time is taken into consideration. The following is an example
+of how a mostly idle process will have a high ELU.
 
-<!-- eslint-skip -->
 ```js
 'use strict';
 const { eventLoopUtilization } = require('perf_hooks').performance;