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Couldn't understand formula for Target first byte Time. - Printable Version

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Couldn't understand formula for Target first byte Time. - Dirst - 08-25-2017 02:34 AM

Hello. I know that this topic has been answered a few times, But I can't reproduce exact formula for target first byte calculation. I almost broke my head off.

For example - here is the test results http://www.webpagetest.org/result/170824_NN_9c3ce7614f669b599263c14d8aa96d53/1/performance_optimization/

As you can see Target FB time - 583 ms Target First Byte Time
Im getting in API
runs->1->firstView
"connect_ms": 161,
"dns_start": 0,
"dns_end": 371,
"connect_start": 371,
"connect_end": 532,
"ssl_start": 0,
"ssl_end": 0,

So as Glossary says Im making calculations:
connect_ms + dns + ssl = 532ms. It is not the result that I see on the above link.

Can you help me, please?


RE: Couldn't understand formula for Target first byte Time. - andydavies - 08-26-2017 01:22 AM

You can see the code here - https://github.com/WPO-Foundation/webpagetest/blob/8c15ef28322ebfe0d34850a4a2751466fb33961d/www/optimization_detail.inc.php#L247

The target is essentially 3 * Round Trip Time + TLS + 100ms


RE: Couldn't understand formula for Target first byte Time. - Dirst - 08-26-2017 02:00 AM

man you are the Man. You just saved my day, thanx