[Codel] Latency vs Delay

[David Collier-Brown]

On 03/14/2015 10:05 PM, David Collier-Brown wrote:
> On 03/14/2015 03:00 PM, divya singla asked
>> Hi Members,
>> is there anybody who can explain me difference between latency and
>> delay?
> In queuing, latency is the time between the send and the first byte of
> the reply, and (total) response time is the time between the send and
> the last byte of the reply. The time between first and last byte is
> the transfer time. Both are stated as if they were being observed by a
> client, either nearby or remote.
>
> Delay, on the other hand, is the time the job spends sitting in a
> queue waiting to start work. Service time is the time it takes to do
> the work. Both are specifically at the server, or "queuing center"
>
> If you draw a diagram, they overlap inconveniently (;-))
>
> --dave
>
>
>

For example, in

\
  |- queue delay
  |- service time
/|- more service time
  |
/

The latency is the time from \ to the first /, and it contains the 
network time, the queuing delay and all the service time required to get 
to the first byte of the reply.

The transfer time is from the \ to the last /, and includes and 
additional service time to get to the last byte of the reply

--dave


-- 
David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb at spamcop.net           |                      -- Mark Twain