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Discrepancy btw TTFB in main html request and WPT table - Printable Version

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Discrepancy btw TTFB in main html request and WPT table - ashana - 09-16-2014 07:14 PM

I am finding big discrepancy btw First byte time that is reported, and TTFB that i see in request -
e.g., First byte time here is rather unusually high here - 1.37 sec
but, time shown in request is,


Request Details
# Resource Content Type Start Offset DNS Lookup Initial Connection SSL Negotiation Time to First Byte Content Download Bytes Downloaded Error/Status Code IP
1 https://www5.v1host....nu=MyHomeSummaryPage text/html 0.498 s 0 ms 20 ms 106 ms 181 ms

0.498 s + 20ms + 106ms + 181 ms adds to - 805 ms much lower than 1.37 sec.

In addition, startOffset - (InitialConnection+SSL) is > 0, and here it is 374 ms - Generally, this value should be close to zero, right?

This one is repeatview numbers - not sure if that affects anything -- One possibility here is that starttime of test can be non-zero for repeat view, and then we have to subtract this initial offset from reported numbers to get actual numbers?


RE: Discrepancy btw TTFB in main html request and WPT table - pmeenan - 09-16-2014 09:55 PM

Do you have a link to the test result? The page-level TTFB includes everything from the start until something comes back (including redirects). In the case of repeat view it may be getting thrown off if for some reason the main resource is being served from cache.


RE: Discrepancy btw TTFB in main html request and WPT table - ashana - 09-17-2014 01:30 AM

(09-16-2014 09:55 PM)pmeenan Wrote:  Do you have a link to the test result? The page-level TTFB includes everything from the start until something comes back (including redirects). In the case of repeat view it may be getting thrown off if for some reason the main resource is being served from cache.

okay, i sent you link to the test result separately.


RE: Discrepancy btw TTFB in main html request and WPT table - ashana - 09-19-2014 03:42 PM

(09-17-2014 01:30 AM)ashana Wrote:  
(09-16-2014 09:55 PM)pmeenan Wrote:  Do you have a link to the test result? The page-level TTFB includes everything from the start until something comes back (including redirects). In the case of repeat view it may be getting thrown off if for some reason the main resource is being served from cache.

Here is the link to webpagetest result

http://www.webpagetest.org/result/140916_7H_dd576d96c595cd0fb3b48b11c4db3791/2/details/cached/

As you can see here, page-level TTFB does not seem to correspond to TTFB from waterfall view

and in repeat view, the starting point is away from zero..