Hacker News new | past | comments | ask | show | jobs | submit login

At first you said pipelining was made to address the issues brought up in the paper, now you are saying you just want to see how it stacks up to pipeling, which are two different things, so don't call it a straw man to give Ivan Sutherland the benefit of the doubt.



The straw man is the part I quoted.

He talked about slow operations that gate your chip. Pipelining explicitly address this. Unless their async units have better hold times than d-flops they will both be gated by propagation delay. It's a straw man since it never mentions pipelining at all.

[edit]Not that I don't have a ton of respect for Sutherland(esp in graphics domain) but it would be nice to see something that admits other approaches.


not quite - pipe stages have costs - both in area and flop delay. In particular a particular flip-flop might have a setup time on it's input and a clk->Q delay - for really fast clocks this might be close to 1/4 your clock period.

For example let's suppose we have a combined flop delay of 1nS and we have a combinatorial delay (the logic we want to calculate) of 9nS - we can clock this at 100MHz, or we can pipeline it 3 ways split the combinatorial block into 3 3nS chunks - each pipe stage still has a 1nS flop delay so total pipe stage delay is 4nS (250MHz) - we split the logic in 3 but only got a 2.5 times performance increase because of fixed costs

Pipelining is a great tool but there is a law of diminishing returns that kicks in here


Thanks, this is the kind of reply I was hoping to get instead of being told I can't comment because some has an important last name.


I never said that, don't turn yourself into a victim.


But you didn't quote anything




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: