THE FOLD / BOSS / THE CHOKE POINT / THE FRAGMENTATION
THE FRAGMENTATION
a requirement nobody agreed to, not a loss
1 WHAT IT IS · WHAT IT DOES · FACT OR FICTION
A disk can be 7% free and unable to store a file of 30 blocks. The space is there. It is in 1,578 pieces and none of them is big enough.
LIT verified live. A 100,000-block disk held at 92.95% used through 40,000 allocate-and-free cycles with a first-fit allocator. 7,054 blocks free, in 1,578 separate runs, mean run 4.5 blocks. The largest contiguous run is 29 — 0.41% of all free space. 15,229 of 40,000 allocations failed while the disk reported free space.
LIT verified live. A 100,000-block disk held at 92.95% used through 40,000 allocate-and-free cycles with a first-fit allocator. 7,054 blocks free, in 1,578 separate runs, mean run 4.5 blocks. The largest contiguous run is 29 — 0.41% of all free space. 15,229 of 40,000 allocations failed while the disk reported free space.
2 HOW IT WAS WEAVED · AI + HUMAN
External fragmentation is why extent-based filesystems exist, why allocators reserve, and why the last 5% of a disk behaves nothing like the first 95%.
AVAN (AI) first ran this on a disk that was 94% free and measured a largest run of 99.62% of free space — no fragmentation at all, because there was nothing to fragment. Fragmentation is a near-capacity phenomenon; the allocator has to be held there or the experiment is not the experiment.
AVAN (AI) first ran this on a disk that was 94% free and measured a largest run of 99.62% of free space — no fragmentation at all, because there was nothing to fragment. Fragmentation is a near-capacity phenomenon; the allocator has to be held there or the experiment is not the experiment.
3 ONE DIMENSION
Free space, and the size of its largest piece.
4 TWO DIMENSIONS · INTERACTIVE
Age the disk and try to allocate.
5 THREE DIMENSIONS + AVAN’S INVERSE
The green forward object: space that exists and cannot be used.
AVAN’s addition (the inverse-companion): the forward reading is that fragmentation wastes free space. The inverse is that no space was lost — a requirement was added that nobody agreed to. All 7,054 blocks are free and writable; what fails is the demand that they be adjacent, and that demand came from wanting sequential reads to be fast. Read backwards, fragmentation is the bill for an optimisation: contiguity was never promised by the disk, it was assumed by the reader, and the allocator has been quietly trying to honour an assumption it was never given.
LIT a 100,000-block disk held at 92.95% used through 40,000 allocate-and-free cycles with a first-fit allocator ends with 7,054 blocks free in 1,578 separate runs of mean length 4.5, a largest contiguous run of 29 which is 0.41% of all free space, and 15,229 of 40,000 allocations failed while the disk reported free space
FIG External fragmentation is why extent-based filesystems exist, why allocators reserve, and why the last 5% of a disk behaves nothing like the first 95%. AVAN first ran this on a disk that was 94% FREE and measured a largest run of 99.62% of free space - no fragmentation at all, because there was nothing to fragment. It is a near-capacity phenomenon; the allocator has to be held there or the experiment is not the experiment.
FIG External fragmentation is why extent-based filesystems exist, why allocators reserve, and why the last 5% of a disk behaves nothing like the first 95%. AVAN first ran this on a disk that was 94% FREE and measured a largest run of 99.62% of free space - no fragmentation at all, because there was nothing to fragment. It is a near-capacity phenomenon; the allocator has to be held there or the experiment is not the experiment.
◆ sealed .dlw.fold → folded to ROOT_0 · a sphere of THE CHOKE POINT · David Lee Wise (ROOT0), with AVAN