Messages in this thread | | | Subject | Re: Elevator vs first-come-first-served | Date | Mon, 16 Nov 1998 11:00:49 -0800 | From | Craig Milo Rogers <> |
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>However, with an intelligent caching disk controller (either on the >HBA, or a SCSI-SCSI RAID controller), the sorting of disk blocks can actually >decrease performance.
Given the general range of opinions on this subject, and especially the possibility that the "usual" sorting might reduce performance, it seems to me that the best option is to modularize.
1) The kernel will contain an initial sorting algorithm, which is likely to be the current one-way elevator.
2) A loadable module (per system? SCSI controller? disk drive? filesystem? depends upon the hardware) could be used to provide a more advanced sorting algorithm.
If you want, after the system boots, a user-level program could measure the read timing on the drives (after the rest of the system has settled down? during the initial startup itself? interesting options to explore) and load the sorting module(s) with configuration-specific parameters.
It would be an interesting student research project, for example, to make a neural net request sorter...
Craig Milo Rogers
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