Re^16: Beyond Agile: Subsidiarity as a Team and Software Design Principle

[BrowserUk]

software is not unlimited either by logic or by the physical world. Rather the differences are differences in abstractions we come up to manage the differences in complexity.

Software is limited by the hardware it runs on; but those limitations are the hardware's limitations, not the software's.

I'll take this slowly, and that is not an implied insult to you, just a necessity, because either I'm really bad at conveying my message -- though historically I've been told I'm reasonably good at that -- or this is one of those concepts -- like quantum mechanics -- that people have a real hard time grasping.

Eg. A 64-bit process can theoretically address 16 EiB (18446744073709551616 bytes); but the first x64 processors had a physical bus limit of 44-bits. That physical reality constrained the performance and capacity of software written for that processor. But with the next generation of hardware x64 chips had a 48-bit bus, so that same software -- if written correctly -- would, without even being recompiled -- would instantly have 16 times its old capacity.

But it doesn't stop there. The same processor that has 16 times the capacity, also halved the latency between chip elements, and effectively doubled the number of those elements available to the chip designer. The first means that the (unchanged) software runs (almost) twice as fast at the same clock speed; the second means that the chip designer can expand the size of the caches; and increase the depth of the instruction pipelines; and increase the number of parallel execution units; with the effect that that at the same clock speed, the cpu can enact the same instructions that on the earliest version took 3, 5, 8, or 21 clock cycles to complete, so that now, almost every instruction completes within a single clock cycle.

So, the same, unchanged, even un-recompiled, software has 16 times its old capacity and executes 2, 4 or even 8 times faster.

Software has only logical limitations.

Contrast that with the fact that building a bridge across the Atlantic Ocean will forever be physically impossible. Traveling to other galaxies will remain physically impossible.

Step 2 follows.

[einhverfr]

Some of those logical limitations come from physical properties, like separation in time or space, right? For example systems *not* separated by time or space would not be subject to the CAP Theorem, right? Is the CAP Theorem therefore not a physical limit?

[BrowserUk]

Some of those logical limitations come from physical properties, like separation in time or space, right? For example systems *not* separated by time or space would not be subject to the CAP Theorem, right? Is the CAP Theorem therefore not a physical limit?

Hm. CAP theorem:

1. I vaguely remember reading something about the conjecture back in the day; but I know nothing about it.
2. I hadn't heard it had been proven; haven't read the proof; and almost certainly wouldn't understand it if I did.
3. It appears that the proof is contentious; but when the one refutation I started to read started getting into Einsteinian relativity; I stopped reading.

My "instant reaction" to CAP theorem is: If I can inject enough delays into the system; I can guarantee consistency. That may be completely undesirable for use; but it makes the limitations logical not physical, at least whilst we're dealing with earthbound distances and real-world system speeds.

Beyond that, I have no opinion; nor interest.