Bandwidth utilization

WebPageTest General Discussion
1

I wanted to know how bandwidth utilization is calculated for a run, I was running wpt for a website and after the DOM Content Loaded event, there’s a pause in Bandwidth utilization from 100% to almost 0, what could be the possible reason for that, because it was still downloading few requests.

http://www.webpagetest.org/result/151221_2Z_CWK/1/details/

Also does js execution halts downloading for time being?

Thanks,
Divyank

2

WPT watches for reads from the network from the browser and every 100ms it logs how much data was read. JS execution shouldn’t block downloads themselves from continuing but if it executes for a while it may block the browser from continuing to read the data. In that case the data is still likely buffering in the network stack in the OS though and the browser will catch up.

If you want to see how the data is flowing more accurately you can capture a tcpdump and plot out the actual packet flow.

3

Thanks for your prompt reply and guidance.