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

["Holland, Jake" <jholland@akamai.com>]

On 2018-11-27, 10:31, "Stephen Hemminger" <stephen@networkplumber.org> wrote:
    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.
    
IIRC they talked about that some too. I think maybe some papers were going back and forth. But last I heard, they proved that this is not a real objection, in that:
1. you can quantify the probability of failure and ensure a design keeps it under threshold when operating within specified conditions (e.g. normal temperature and voltage thresholds)
2. you can work around the issues where it's critical by adding failure detection and faults, and
3. you have the exact same fundamental theoretical problem with synchronous circuits, particularly in registers that can keep a value through a clock cycle, but it hasn't stopped them from being useful.

I'm not an expert and this was all a long time ago for me, but  the qdi wiki page doesn't disagree with what I'm remembering here, and has some good references on the topic:
https://en.wikipedia.org/wiki/Quasi-delay-insensitive_circuit#Stability_and_non-interference
https://en.wikipedia.org/wiki/Quasi-delay-insensitive_circuit#Timing