On Sat, 2008-08-09 at 13:12 -0400, Knight, Frederick wrote: > You are free to create a single pair API between your filesystems and > drivers and send SCSI commands one LBA/length pair at a time. However, > I'm afraid the voting members of T10 (representing a number of other > operating systems and their multitude of filesystems) preferred the list > approach. That seems like unneeded complexity to me. Admittedly the sample set of file systems I've converted to use this is small so far -- only 2 -- but it seems to me that it's always likely to be done in the 'free extent' code path as we mark blocks free, and I can't see the file system really taking advantage of the ability to pack multiple regions into the same request. It's hard for I/O elevators to merge these requests when they're not contiguous, too -- it would require a lot of special-casing to make it happen at that level. It's also somewhat suboptimal that it doesn't match the T13 'TRIM' proposal, which allows only a single range to be specified. That'll be fun for anyone doing SCSI<->ATA conversion... Has anyone actually claimed that they can and will use the list form, and have they also told the T13 forum the same thing? -- David Woodhouse Open Source Technology Centre David.Woodhouse@xxxxxxxxx Intel Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
