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Neat! I have several questions here. First of all, why does Linux not need defragmentation?

Second, is it actually true that it doesn't need it? The readme implies that this defragmenter (for Linux) produces actual benefits.

Third, it says the benefits exist even on NVMe, i.e. on SSDs? I thought defragging was relevant for spinny disks only?

Thanks

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Mostly, they try to avoid it by allocating extents instead of blocks (so, they look for a contiguous space to store most files) and by delaying allocation to accommodate for a growing files.

My observation is that it is not completely true. I constantly have a close to full partition in ext4 and there is no secrets when there is no space the filesystem WILL create a bazillion of small extents because, it has no physical choice! and everytime you have a non maxed out extent, it will create an overhead I don't see how magically you can avoid that. And it is not like a few, on my main working partition, extends of a few KB by the thousands per files are created instead of the optimal size of 128MB. If you just use defrag in read mode on it, it is red from top to bottom, you cannot find a block of few MB with no fragmented file in it.

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