Messages in this thread | | | Date | Tue, 27 Mar 2001 13:35:23 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: Larger dev_t |
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On Tue, 27 Mar 2001, Alan Cox wrote: > > > layer made it impossible for a driver writer to be nice to the user, so > > instead they got their own major numbers. > > Not deficiencies in the SCSI layer, there is no way the scsi layer can > handle high end raid controllers. In fact one of the reasons we can beat > NT with some of these controllers is because NT does exactly what you > suggest with scsi miniport driver hacks and it _sucks_. Its an ugly hack.
We could do this fairly _trivially_ today.
With absolutely no performance degradation.
With a simple "queue" mapping for the SCSI majors. Just look up which queue to use for requests to which major, and you're done. The actual IO may by-pass the SCSI layer altogether.
So I'm absolutely not advocating using the SCSI layer for the high-end-disks. Rather the reverse. I'm advocating the SCSI layer not hogging a major number, but letting low-level drivers get at _their_ requests directly.
Linus
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