SSD/NVMe keep track of what regions are wiped and which contain data that has to be preserved. To hide something in the seemingly-unused space, you have to turn off trim, eat the performance cost, and pretend you had a reason to have turned off trim.
I don't believe having trim disabled even helps here. smart firmware sees the same address being written to and may therefore reassign it to a different cell for wear leveling. it's a de facto trim.
trim lets the firmware know which mappings it can discard without the explicit reuse of the same address.
however I don't believe you can observe this effect from trim command results, it will report the usual size trimmed as if the firmware never realized that you reused the same address range multiple times.
JJ's use of the Git file format is done via https://github.com/GitoxideLabs/gitoxide -- there's still some missing features in the networking part, but the local-file-manipulation features are fully there.
Great lib. I meant libdog, a different thing. gitoxide is like "git implemented in Rust" while libdog is "git's necessary primitives in C" (objects, packs, sync proto, own index format, diff/merge, etc). As a result, gitoxide is 270KLoC while libdog is 24KLoC, plus 44KLoC of tokenizers. libdog uses token-level algorithms for diff, merge, blame. It also does syntax highlighting in the pager - they all need grammars.
icache pressure was the bane of my optimization work around 2002. Mostly because it fluctuated unpredictably even from fairly small fairly faraway changes. The system got large enough, with a long enough hot code path that was very hot, that it was almost pointless to benchmark a subsystem in isolation. Simplistic attempts to make any subsystem faster typically made the whole system slower.
In general, whatever subsystem took the cache misses showed up as the slow part, and I owned the very first component in the pipeline... It was fun to compile time disable my component to demonstrate that nothing got faster, though.
Just like xAI was regulated to not run more than 15 gas turbines? US lets companies get away with breaking things and punishes wrongdoing at most with a fine that's less than the money that was made by breaking the rules, so US regulations sort of don't matter.
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