Yes, one of them will be in the right place: but the others will be all over the shop, and the device will have to satisfy those very soon as well, so as to free up space for more requests.
If space for requests is the issue, it doesn't matter which requests you satisfy -- they all return the same kind of space. You can ignore the distant requests as long as you want
I thought you'd point out that the general purpose head scheduling algorithm stresses response time, so would satisfy those distant requests soon. But fsck doesn't need response time, and should use a head scheduling algorithm that satisfies the near requests first regardless. You can let 990 of those threads wallow while the disk cycles through requests from the 10 that happen to be working in the same region of the disk.
I would much rather see the device driver than the application doing head scheduling. Only the device driver really knows the seek issues.
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