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This problem is similar to (and exacerbated by) the IO bottlenecks VMs experience when using traditional hard drive disks, due to high levels of random IO operations. For this reason, many new virtual setups are using solid state drives, which have no seek time. This keeps the high level of random IO operations from significantly impacting performance.

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> For this reason, many new virtual setups are using solid state drives, which have no seek time. This keeps the high level of random IO operations from significantly impacting performance.

Except for btrfs, where it would make the whole thing even less efficient (because now the only cost is the waiting around for threads, not even the random seek on your platters).

And as a result, I disagree with your "and exacerbated by". BTRFS's problem becomes worse on SSDs (qualitatively) because the random read itself is almost free, and all of the cost is in the context switching done by the FS, instead of only 80~90% of that cost.

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