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I just received this report from pingdom:

enter image description here

Ans was wondering how do they know the 'response time' information regarding the site. The GET request does not give that information.

Mark Henderson
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donald
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3 Answers3

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You ask a question and take the time until the answer arrives. Easy.

Edit: A very basic and unexact example: 

rivendell:~ sw$ time curl serverfault.com > /dev/null
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  126k  100  126k    0     0  84088      0  0:00:01  0:00:01 --:--:-- 97802

real    0m1.545s
user    0m0.004s
sys  0m0.009s
Sven
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  • Can you give me an example? How do you ask a question? – donald Feb 03 '11 at 18:45
  • Well, their service just requests a website from your server and measures the time until it arrives. Not sure what time they measure: When the answer starts to arrive or when it's finished, I am not an expert in Web performance. See my edit for a very stupid method of measuring something like that. – Sven Feb 03 '11 at 18:52
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... was wondering how do they know the 'response time' information regarding the site.

I am not sure what exactly Pingdom does, but the standard seems to be to measure the complete page load time, but without images:

See for example: http://www.alertfox.com/Tools/LoadTime/

"This test measures the response time (HTML load time without images) from three monitoring stations distributed worldwide."

Technically that is the same as http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.aspx

FrankPython
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"The GET request does not give that information."

No that's true, so that is why services like Pingdom start a timer and measure when the GET request has completed.

A more sophisticated way of measuring page load time is using a real browser, like here: loads.in

pors
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