alt Hacker NewsI like the graphical interface and the movement of the blocks. Brings back memories of defragmenting hard drives once a month and seeing noticeable performance improvements sometimes.
> Fragmentation and extent allocation were adding measurable variance, even on NVMe,
Why exactly would there be a measurable variance on NVMe? I understand there could be some impact on magnetic hard drives. This sounds like some sort of coincidence due to other factors and that this defragmentation won’t achieve much (except for wearing out your SSD even faster in certain cases).
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SSD still have slower reads when the data isn't sequential. Not slow enough to matter, especially with extents meaning the data is probably in a handful of locations, not 10000, but it's absolutely measurable if your blocks are small enough (<1MB typically, though disk benchmarks usually use 64KB random reads and sometimes 4KB).
>defragmentation won’t achieve much
Indeed, most Linux setups supporting trim, already defer these operations to a weekly schedule to reduce wear, and most fs will optimize in 10MB or 25MB chunks given unlike HDD... the SSD seeks are nearly constant time. Logging fs like f2fs, are content aware so will auto re-locate hot and cold (rarely modified) file types, and despite the log-structure... on an SSD performance losses are often surprisingly negligible.
Most modern NVMe with dram cache and SLC buffer areas also defer committing pages to low-endurance flash areas. And most kernel tweakers will set swapiness to 1 on SSD/NVMe machines to try to keep stuff buffered in dram as long as reasonably possible. It is a space-time tradeoff that can boost a desktop machine performance especially with preload daemon active.
If people want ludicrous speed... than just run ext4 with a separate 128GB journal NVMe drive on a split PCIe x4 bus.
Defrag on most modern drives usually just fills these buffer areas full, and things grind to the slowest i/o choke point. =3