Re: Software Pipelining

> I believe software pipelining can improve performance even when there
> are only a few functional units.
> For example, suppose the following code is run on a machine with a
> single FU.
> All the
> It is just incrementing an array of 10 elements.
>
> ldc r0, 0
> L1:
> 0. load r1, 0(r0) # latency 2
> 1. add r1, r1, 1 # latency 1
> 2. store 0(r0), r1 # latency 1
> 3. add r0, r0, 1 # latency 1
> 4. cmp r0, 10 # latency 1
> 5. blt L1 # latency 1
>
> For a non-SW pipelined code, a single iteration would take 7 cycles.
> Now, for the SW pipelined code, a single iteration would take 6 cycles
> on average.


Even though I understand that this is an example, I still
have the feeling that with just a single functional unit, the
benefits of pipelining are marginal, in your example it's just
about 1 cycle. But I also agree that this might have some
positive effect when the loop has a high iteration count.

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