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Metrics
Parashuram N edited this page Jul 9, 2014
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The following metrics are measured. The tool is modular and other custom metrics can be added.
[Work in progress, filling this up now]
These metrics are obtained from the Chrome Developer Tools timeline. They are the same metrics you see in the timeline when a web page is profiled.
| Name | Unit | Description |
|---|---|---|
| CompositeLayers | ms | The time spent compositing rendering layers into a screen image |
| DecodeImage | ms | The time spent decoding images |
| EvaluateScript | ms | The time spent evaluating the page's scripts |
| EventDispatch | ms | The time spent executing event handlers |
| FireAnimationFrame | ms | The time spent handling scheduled animation frame events |
| FunctionCall | ms | The time spent executing calls to top-level Javascript functions |
| GCEvent | ms | The time spent doing garbage collection during script execution |
| Layout | ms | The time spent on (re)flow, or constructing the rendering tree from the DOM tree |
| Paint | ms | The time spent rasterizing the page into bitmaps |
| PaintSetup | ms | The time spent converting DOM elements into a display list of drawing commands to paint |
| ParseHTML | ms | The time spent executing the engine's HTML parsing algorithm |
| Program | ms | The total time for all actions to render the page |
| RecalculateStyles | ms | The time spent recalculating element styling, when a reflow occurs |
| TimerFire | ms | The time spent executing timer-triggered handlers |
| XHRReadyStateChange | ms | The time spent handling handling changes to the ready state of XMLHTTPRequest's |
| Name | Unit |
|---|---|
| droppedFrameCount | count |
| numFramesSentToScreen | count |
| numAnimationFrames | count |
| Name | Unit |
|---|---|
| Layers | count |
| PaintedArea_total | sq pixels |
| PaintedArea_avg | sq pixels |
| NodePerLayout_avg | count |
| ExpensivePaints | count |
| GCInsideAnimation | count |
| ExpensiveEventHandlers count |
These are calculated from window.performance.timing API in NavTimingMetrics. For more information about each metric, please the W3C Specification
| Name | Unit | Description |
|---|---|---|
| connectStart | ms | The time immediately before the user agent started establishing the connection to the server to retrieve the document |
| connectEnd | ms | The time immediately after the user agent finished establishing the connection to the server to retrieve the document |
| domComplete | ms | The time immediately before the user agent set the document's readiness to complete |
| domContentLoadedEventStart | ms | The time immediately before the user agent fired the DOMContentLoaded event |
| domContentLoadedEventEnd | ms | The time immediately after the document's DOMContentLoaded event completed |
| domInteractive | ms | The time immidiately before the user agent set the document's readiness to interactive |
| domLoading | ms | The time immidiately before the user agent set the document's readiness to loading |
| domainLookupStart | ms | The time immediately before the user agent started the domain name lookup for the document |
| domainLookupEnd | ms | The time immidiately after the user agent finishes the domain name lookup for the document |
| fetchStart | ms | The time immediately before the user agent checks caches for resources OR starts fetching resources |
| firstPaint | ms | The time immediately before the first paint occurred |
| loadEventStart | ms | The time immediately before the load event was fired for the document |
| loadEventEnd | ms | The time the load event for the document completed |
| requestStart | ms | The time immediately before the user agent started requesting the document from the server |
| responseStart | ms | The time immediately after the user agent received the first byte of the server's response to the document request |