Meaning and calculation formulas for Processing Time,Latency and Response Time [closed]

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Closed 8 years ago.

can anybody verify the Processing Time,Latency and Response Time Formulas from the below picture.I have some doubt in Response Time Formula.

Please give me proof reference if you have conflict with my these formulas.

Answer 1

I would take the;

• worst case latency as being T8 - T1 also elapse time
• processing time T6 - T3 also response time as you can start processing from the first byte and still be processing up to the last byte.

If you can't start processing the message on the server until you get the last byte, you have to use the last byte for the latency as well, otherwise its inconsistent.

I would assume the server is more highly tuned for performance than the client i.e. it might start processing from the first packet, but the client might need the whole message to do anything useful (this depends on the client)

Answer 2

I agree with Peter regarding processing time and worst case latency : T6 - T3

But for Latency, I would say it's T7 -T1. I consider it as time to first byte.

In JMeter it's:

JMeter measures the latency from just before sending the request to just  
after the first response has been received. Thus the time includes all the processing 
needed to assemble the request as well as assembling the first part of the response, 
which in general will be longer than one byte. Protocol analysers (such as Wireshark) 
measure the time when bytes are actually sent/received over the interface. The JMeter 
time should be closer to that which is experienced by a browser or other application
client. 

Also look at:

• Latency Time in Load Testing

Answer 3

From wikipedia:

In a data system, the system response time is the interval between the receipt of the end of transmission of an inquiry message and the beginning of the transmission of a response message to the station originating the inquiry.

Which should be T5-T4 (just like processing time).