Re: [Bloat] one benefit of turning off shaping + fq_codel

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 27 Nov 2018 18:14:01 +0000
"Holland, Jake" <jholland@akamai.com> wrote:

> On 2018-11-23, 08:33, "Dave Taht" <dave@taht.net> wrote:
>     Back in the day, I was a huge fan of async logic, which I first
>     encountered via caltech's cpu and later the amulet.
>     
>     https://en.wikipedia.org/wiki/Asynchronous_circuit#Asynchronous_CPU
> 
> ...
>     
>     I've never really understood why it didn't take off, I think, in part,
>     it doesn't scale to wide busses well, and that centrally clocked designs
>     are how most engineers and fpgas and code got designed since. Anything
>     with delay built into it seems hard for EEs to grasp.... but I wish I
>     knew why, or had the time to go play with circuits again at a reasonable
>     scale.
>     
> At the time, I was told the objections they got were that it uses about 2x the space for the same functionality, and space usage is approximately linear with the chip cost, and when under load you still need reasonable cooling, so it was only considered maybe worthwhile for some narrow use cases.
> 
> I don't really know enough to confirm or deny the claim, and the use cases may have gotten a lot closer to a good match by now, but this was the opinion of at least some of the people involved with the work, IIRC.
> 
> 
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With asynchronous circuits there is too much unpredictablity and instability.
Seem to remember there are even cases where two inputs arrive at once and output is non-determistic.