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Re: [oc] Delay and latency ?
Aloha!
saumil merchant wrote:
> Hey !
> Can anybody throw some light on difference between delay and latency ?
In HW design it works like this:
Latency is the number of clock cycles required to perform a certain task. For
example stepping through the stages of a data path.
Delay is the physical time (normally measured in ns) for something. For
example the delay through a gate, setup time for an I/O, arrival time on an
input etc.
After mapping a design to a specific technology, the maximum delay yields the
cycle time needed to propagate the inputs through a combinational net and get
a stable output that can be sampled by the next register/latch.
For a mapped design you therefore get the maximum frequency as a function of
the delay. The latency as a number of cycles and by multiplying cycled with
delay, the physical time to do the calculation. And finally, the throughput as
the latency (in cycles) times the frequency.
Rule to remember: RTL does not know about delay, only latency.
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Med vänlig hälsning, Yours
Joachim Strömbergson - Alltid i harmonisk svängning.
VP, Research & Development
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