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by dmitrygr 162 days ago
“Why don’t we do $thing_that_decisively_failed instead of $thing_that_evolved_to_beat_all_other_approaches?” Usually this sort of question comes from a lack of understanding of the history of the failure of the first and the success of the second.

The fence principle always applies “don’t tear down a fence till you understand why it was built”

Linear address spaces allow for how computers actually operate - layers. Objects are hard to deal with by layers who don’t know about them. Bytes aren’t. They are just bytes. How do you page out “an object”? Do I now need to solve the knapsack problem to efficiently tile them on disk based on their most recent use time and size? …1000 other things…
2 comments
musicale 162 days ago
IIRC Multics (among other systems) had both segmentation and paging, and a unified memory/storage architecture.

[I had thought that Multics' "ls" command abbreviation stood for "list segments" but the full name of the command seems to have been just "list". Sadly Unix/Linux didn't retain the dual full name (list, copy, move...) + abbreviated name (ls, cp, mv...) for common commands, using abbreviated names exclusively.]

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GeorgeTirebiter 162 days ago
Correct. 'Segments' are the Proper Unit to think about a bag of bits doing a computation; pages sitting under segments is how VM systems worked to only load the active parts of segments; that's kind of what defined Demand Paging. We have got to get back to the garden here, we need to start valuing security and safety at least as much as raw speed. https://en.wikipedia.org/wiki/Multics?useskin=vector Tagged memory, Capabilities (highly granular), and, yes, segments. Probably needs a marketing refresh (renaming) so as to not be immediately discarded.
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philipallstar 162 days ago
> The fence principle always applies “don’t tear down a fence till you understand why it was built”

Don't rename Chesterton's Fence until you understand why it was named that.

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dmitrygr 161 days ago
Was not aware the fence had a name. Learned it in Russian without the name. TIL, thank you.
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philipallstar 161 days ago
Well, it is possible Chesterton got it from an earlier source that the Russian version also derives from! Who knows?
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